Volume 11, Issue 1, Revisiting Piriformis Syndrome: 15 Years of Research

We began our reSearch publication in April of 2006 and have covered a variety of topics over the past ten years.  In this issue of reSearch we are revisiting one of the earliest topics, searching our database REHABDATA and a few new databases to provide updated information on Piriformis Syndrome (PS).  

According to the National Institute of Neurological Disorders and Stroke’s Information Page on PS and WebMD:  Piriformis syndrome is a rare neuromuscular disorder that occurs when the piriformis muscle compresses or irritates the sciatic nerve.  The piriformis muscle is a flat, narrow band-like muscle located in the buttocks near the top of the hip joint and is important to lower body movement as the muscle stabilizes the hip joints and lifts and rotates the thigh away from the body.  The sciatic nerve is the longest nerve in the body passing alongside and through the piriformis muscle, going down the back of the leg, and then branching off into smaller nerves ending that end in the feet.  The piriformis muscle enables individuals to walk, shift weight from one foot to the other (side to side), and maintain balance.  This muscle is also used in sports that involve lifting and rotating the thighs as well as in almost every motion of the hips and legs (i.e., running, jogging, etc.) (http://www.ninds.nih.gov/disorders/piriformis_syndrome/piriformis_syndrome.htm & http://www.webmd.com/pain-management/guide/piriformis-syndrome-causes-symptoms-treatments).  

In the case of PS, the piriformis muscle impinges (compresses) on the sciatic nerve either as a result of an issue with the muscle itself or due to injury.  It can be difficult to diagnosis PS as the symptoms often mimic sciatica – a disorder that extends from the hip down the back of the thigh and surrounding areas resulting pain, inflammation, tenderness, tingling, and numbness. The causes of sciatica can range from a herniated disc, bone spur on the spine, or narrowing of the spine (spinal stenosis) which compresses part of the nerve (http://www.mayoclinic.org/diseases-conditions/sciatica/basics/definition/con-20026478). 

How is PS diagnosed?  

According to WebMD there is no definitive test for PS and physicians often rely on the patient to provide information on symptoms and medical history (i.e., trauma to the area, repetitive/vigorous activity, or prolonged sitting) and a physical examination.  Because symptoms may be similar to other conditions your physician/specialist may order radiological tests such as magnetic resonance imaging (MRI) to rule out other causes of sciatic nerve compression (i.e., herniated disc, bone spur, or spinal stenosis) (http://www.webmd.com/pain-management/guide/piriformis-syndrome-causes-symptoms-treatments). 

How is PS treated?

Your physician, specialist, and/or physical therapist may prescribe a course of treatment that may include anti-inflammatory medications; exercises and stretches to help reduce sciatic nerve compression; cessation of running, bicycling, or similar activities and avoidance of certain activities/positions that trigger pain; and massage and/or osteopathic manipulative treatment as well as acupuncture to help alleviate pain and increase range of motion.  Additional medications may include muscle relaxants, corticosteroid injections, and injections of the botulinum toxin (botox).  Finally, in some cases surgery may be recommended (http://www.ninds.nih.gov/disorders/piriformis_syndrome/piriformis_syndrome.htm & http://www.webmd.com/pain-management/guide/piriformis-syndrome-causes-symptoms-treatments). 

This edition of reSearch provides a “snapshot” of over 10 years of research on piriformis syndrome.  This “snapshot” presents a general overview of piriformis syndrome and various treatment methodologies.  The combined search terms for this edition of reSearch included:  piriformis syndrome, sciatica, piriformis muscle, sciatic nerve, and neuromuscular conditions.  A listing of over 150 additional descriptor terms between the NARIC, CIRRIE, Cochrane, PEDro, and PubMed databases can be found at the end of this document.

A search of the REHABDATA database resulted in 5 documents published between 2002 and 2012. The CIRRIE and Cochrane database searches results in 1 document from 2010 and 2011, respectively.  A search of PEDro, a database specializing in physiotherapy evidence-based research, resulted in 4 documents published between 2006 and 2015.  Finally, a search of the PubMed database resulted in 56 documents between 2006 and 2015.  Sixty-one new citations on piriformis syndrome between all the aforementioned databases are included in this research brief. 


Piriformis Syndrome (n.d.).  National Institute on Neurological Disorders and Stroke.  NINDS Piriformis Syndrome Information Page.  Retrieved from http://www.ninds.nih.gov/disorders/piriformis_syndrome/piriformis_syndrome.htm.

Piriformis Syndrome (n.d.).  WebMD Online.  Pain Management Health Center.  Retrieved from http://www.webmd.com/pain-management/guide/piriformis-syndrome-causes-symptoms-treatments.  

Sciatica (n.d.). MayoClinic Online.  In Diseases and Conditions.  Retrieved from http://www.mayoclinic.org/diseases-conditions/sciatica/basics/definition/con-20026478.  

NIDILRR Funded Projects Related to Piriformis Syndrome

In addition to document searches, we searched our NIDILRR Program Database to locate grantees/projects related to Piriformis Syndrome.  While no specific projects address this condition, we identified several on directly-related topics (i.e., exercise, fitness, mobility, muscular issues and trauma).  The search resulted in 13 currently funded and 13 projects that are no longer active.  Project information and their publications are offered as additional resources for our patrons.

Advanced Rehabilitation Research Training Center on Neuro-Musculoskeletal Rehabilitation
Project Number: 90AR5011 (formerly H133P110014)
Phone: 973/324-3550
Email: pbarrance@kesslerfoundation.org.

Development of a Pediatric Intelligently Controlled Assistive Rehabilitation Elliptical (Pedi-ICARE) Training System to Promote Walking and Fitness in Children with Physical Limitations
Project Number: 90IF0060 (formerly H133G130274)
Phone: 402/413-4505
Email: jburnfield@madonna.org.

Dose-Response Effects of Transformative Exercise in Improving Health and Function in Adults with Spinal Cord Injury and Multiple Sclerosis
Project Number: 90DP0059 (formerly H133A130044)
Phone: 205/975-9010
Email: jrimmer@uab.edu.

Dynamic Supported Mobility for Infants and Toddlers with Cerebral Palsy
Project Number: 90IF0076 (formerly H133G140166)
Phone: 215/590-2495
Email: prosserl@email.chop.edu.

Interactive Exercise Technologies and Exercise Physiology for People with Disabilities
Project Number: 90RE5009 (formerly H133E120005)
Phone: 205/975-9010
Email: jrimmer@uab.edu.

Machines Assisting Recovery from Stroke and Spinal Cord Injury for Reintegration into Society (MARS3)
Project Number: 90RE5010 (formerly H133E120010)
Phone: 312/238-1277
Email: j-patton@northwestern.edu.

Project WOWii: Developing and Testing a Web-Based Intervention to Promote Exercise Among Those with Spinal Cord Injury
Project Number: 90IF0091
Phone: 214/648-1054
Email: katherine.froehlichgrobe@uth.tmc.edu.

Rehabilitation Engineering Research Center on Technologies to Support Successful Aging with Disability (RERC TechSAge)
Project Number: 90RE5016 (formerly H133E130037)
Phone: 404/894-1413
Email: jon.sanford@coa.gatech.edu.

Rehabilitation Research and Training Center on Developmental Disabilities and Health
Project Number: 90RT5020 (formerly H133B130007)
Phone: 312/413-1647 (V), 800/996-8845 (V), 312/413-0453 (TTY)

Rehabilitation Research and Training Center on Secondary Conditions in Spinal Cord Injury
Project Number: 90RT5002 (formerly H133B090002)
Phone: 202/877-1694
Email: inger.h.ljungberg@medstar.net.

RRTC on Developing Optimal Strategies in Exercise and Survival Skills to Increase Health and Function
Project Number: 90RT5027 (formerly H133B140012)
Phone: 312/238-4864
Email: eroth@ric.org.

University of Washington Rehabilitation Research and Training Center on Promoting Healthy Aging for Individuals with Long-Term Physical Disabilities
Project Number: 90RT5023 (formerly H133B130018)
Phone: 866/928-2114
Email: agerrtc@uw.edu.

Weight Management and Wellness for People with Psychiatric Disabilities
Project Number: 90IF0100
Phone: 312/355-1696 (V), 312/422-0706 (TTY)
Email: jonikas@psych.uic.edu.

These projects have completed their research activities and are now closed.  

Development of an Intelligently Controlled Assistive Rehabilitation Elliptical (ICARE) Training System to Promote Walking and Fitness in Persons with Physical Limitations
Project Number: H133G070209
Phone: 402/483-9669
Email: jburnfield@madonna.org.

The Effectiveness of an Off-Axis Elliptical Training Program on Improving Gait Function in Children with Cerebral Palsy
Project Number: H133F130031
Phone: 404/413-1246.
Email: ltsai@gsu.edu.

ENhancing ACTivity and Participation for Persons with Arthritis (ENACT)
Project Number: 90RT5009 (formerly H133B100003)
Phone: 617/353-2735
Email: jkeysor@bu.edu.

Evaluating the Effects of Activity-Based Therapy for Individuals with Chronic Spinal Cord Injury
Project Number: H133G080031
Phone: 404/350-7595
Email: mike_jones@shepherd.org.

Health Activity Rehabilitation Research Training Center (HARRTC)
Project Number: H133P050005
Phone: 573/884-1499
Email: holtmeyerk@health.missouri.edu.

Multitherapy Approach to Tendon Rehabilitation
Project Number: H133G20178
Phone: 913/588-6799
Email: enwemeka@kumc.edu.

Musculoskeletal Disorders in Children and Adults, Including Arthritis
Project Number: G008300042

Muscle Strength, Physical Work Capacity, and Functional Performance in Individuals with Down Syndrome
Project Number: H133G040323
Phone: 217/333-2131
Email: fernhall@uiuc.edu.

NEW DOOR: Nutrition, Exercise, Weight Management & Disability Obesity Options and Resources
Project Number: 90IF0001 (formerly H133G120093)
Phone: 510/225-6349
Email: marsax@wid.org.

Rehabilitation Engineering Research Center for Successful Aging with Disability: Optimizing Participation Through Technology (OPTT-RERC)
Project Number: 90RE5002 (formerly H133E080024)
Phone: 323/442-2903
Email: winstein@usc.edu.

Rehabilitation Research and Training Center in Neuromuscular Diseases (RRTC-NMD)
Project Number: 90RT5001 (formerly H133B090001)
Phone: 916/734-4280
Email: scott.branum@ucdmc.ucdavis.edu.

Sensorimotor Training and Assessment in Adults with Hemiplegic Cerebral Palsy: The ULTrA Program
Project Number: H133G050151
Phone: 734/763-6755
Email: shcb@umich.edu.

Video Gaming Technology to Promote Health and Fitness Among Adolescents with Disabilities
Project Number: H133G100278
Phone: 409/772-9498
Email: jerowlan@utmb.edu.

Why do I see different grant numbers?   

In 2014, President Obama signed the Workforce Innovation and Opportunity Act (WIOA) into law. As part of WIOA, the institute changed its name from the National Institute on Disability and Rehabilitation Research (NIDRR) to the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR) and moved from the Department of Education to the Administration for Community Living (ACL) at the Department of Health and Human Services. Approximately 250 active grants received new ACL grant numbers and all new grants funded under NIDILRR have only an ACL grant number.  For more information about NIDILRR/ACL grant numbers please visit:  http://naric.com/?q=en/content/about-nidilrracl-grant-numbers-0.

Documents from NARIC’s REHABDATA search listed are listed below:

2012 – NEW!

Grinberg, Y., Gustafson, K.J., Joseph, S., & Triolo, R.J.  (2012).  Human distal sciatic nerve fascicular anatomy: Implications for ankle control using nerve-cuff electrodes.  Journal of Rehabilitation Research and Development (JRRD) (formerly the Bulletin of Prosthetics Research), 49(2), 309-322.
NARIC Accession Number: J63551
ABSTRACT: Study examined the fascicular anatomy of the human lower sciatic nerve and evaluated the potential of selective activation of ankle musculature with a multicontact nerve-cuff electrode. Eight human sciatic nerves were examined in four formalin-fixed female cadavers. Three complete sciatic nerves and branches were dissected from the piriformis to each muscle entry point to characterize the branching patterns and diameters. Fascicle maps were created from serial sections of each distal terminus below the knee through the anastomosis of the tibial and common fibular nerves above the knee. Similar branching patterns and fascicle maps were observed across specimens. Fascicles innervating primary plantar flexors, dorsiflexors, invertors, and evertors were distinctly separate and functionally organized in the proximal tibial, common fibular, and distal sciatic nerves; however, fascicles from individual muscles were not apparent at these levels. The fascicular organization is conducive to selective stimulation for isolated and/or balanced dorsiflexion, plantar flexion, eversion, and inversion through a single multicontact nerve-cuff electrode. These neuroanatomical data are being used to design nerve-cuff electrodes for selective control of ankle movement and improve current lower-limb neural prostheses.

2006 – NEW!

Chang, K-F, Chang, S-W, Li, C-M, Shieh, S-F, & Wu, W-T.  (2006).  Measurement of motor nerve conduction velocity of the sciatic nerve in patients with piriformis syndrome: A magnetic stimulation study.   Archives of Physical Medicine and Rehabilitation, 87(10), 1371-1375.
NARIC Accession Number: J51440
ABSTRACT: The motor nerve conduction velocity (MNCV) was measured at the gluteal segment of the sciatic nerve by magnetic stimulation in patients with piriformis syndrome and healthy control subjects, and compared with the conventional electrodiagnostic methods. The mean value for MNCV of the sciatic nerve at the gluteal segment from L5 nerve root to gluteal fold in patients with piriformis syndrome was significantly slower than the mean value of the same segments in controls. The MNCV of the sciatic nerve in S1 component showed no significant difference between the patients and controls. A negative relationship was found between the disease duration and the MNCV values of sciatic nerves in patients with piriformis syndrome.

Hurdle, M-F., Locketz, A.J., Smith, J., & Wisniewski, S.J.  (2006).  Ultrasound-guided piriformis injection: Technique description and verification.   Archives of Physical Medicine and Rehabilitation, 87(12), 1664-1667.
NARIC Accession Number: J51766
ABSTRACT: Article describes a technique for performing ultrasound-guided piriformis injections.  Piriformis injections are commonly used in the evaluation and treatment of patients with buttock pain syndromes. The piriformis is traditionally injected using electromyographic, fluoroscopic, computed tomographic, or magnetic resonance imaging guidance. Ultrasound offers several advantages over traditional imaging approaches, including acceptability, compact size, lack of ionizing radiation exposure, and direct visualization of neurovascular structures.


Bond, M.J., Broadhurst, N.A., & Simmons, N.  (2004).  Piriformis syndrome: Correlation of muscle morphology with symptoms and signs.   Archives of Physical Medicine and Rehabilitation, 85(12), 2036-2039.
NARIC Accession Number: J48380
ABSTRACT: Presents study conducted to determine whether patients with low back or buttock pain had any piriformis muscle abnormalities and to correlate the diagnostic findings with two symptoms and two clinical signs commonly associated with patients who have buttock pain. The piriformis muscle was injected with bupivacaine after pain was assessed on a visual analog scale using the resisted abduction test. The symptoms examined were pain going up inclines or stairs and pain referred to the posterior thigh. The signs were pain on resisted abduction of the adducted flexed hip and pain produced by needling the muscle. Odds ratios and 95 percent confidence intervals were calculated comparing each of the signs and symptoms with normal morphology. The highest odds ratios were found for pain on walking up inclines (10.8), referred pain (5.3) and pain on needling the piriformis muscle (6.0).


Dombi, G.W., Fishman, L.M., Michaelsen, C., Ringel, S., Rosner, B., Rozbruch, J., & Weber, C.  (2002).  Piriformis syndrome: Diagnosis, treatment, and outcome: A 10-year study.   Archives of Physical Medicine and Rehabilitation, 83(3), 295-301.
NARIC Accession Number: J43761
ABSTRACT: Study was conducted to validate an operational definition of piriformis syndrome based on prolongation of the H-reflex with hip flexion, adduction, and internal rotation (FAIR) and to assess surgical and nonsurgical treatments. Researchers develop working diagnostic criteria, validate evidence of the syndrome, and assess treatment of cases diagnosed by each criterion. Authors conclude that the FAIR test correlates well with a working definition of piriformis syndrome and is a better predictor of successful physical therapy and surgery than the working definition. The FAIR test, used in conjunction with injections and physical therapy and/or surgery, appears to be effective for diagnosing and treating piriformis syndrome.

Document from the Center for International Rehabilitation Research Information Exchange (CIRRIE-3) search at cirrie.buffalo.edu are listed below:

2010 – NEW!

Hopayian, K., Riera, R., Sambandan, S., & Song, F.  (2010).  The clinical features of the piriformis syndrome:  A systematic review.  European Spine Journal, 19(12), 2095-109.
Available in full-text at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2997212.  
ABSTRACT: Piriformis syndrome, sciatica caused by compression of the sciatic nerve by the piriformis muscle, has been described for over 70 years; yet, it remains controversial. The literature consists mainly of case series and narrative reviews. The objectives of the study were: first, to make the best use of existing evidence to estimate the frequencies of clinical features in patients reported to have PS; second, to identify future research questions. A systematic review was conducted of any study type that reported extractable data relevant to diagnosis. The search included all studies up to 1 March 2008 in four databases: AMED, CINAHL, Embase and Medline. Screening, data extraction and analysis were all performed independently by two reviewers. A total of 55 studies were included: 51 individual and 3 aggregated data studies, and 1 combined study. The most common features found were: buttock pain, external tenderness over the greater sciatic notch, aggravation of the pain through sitting and augmentation of the pain with manoeuvres that increase piriformis muscle tension. Future research could start with comparing the frequencies of these features in sciatica patients with and without disc herniation or spinal stenosis.

Document from the Cochrane Database of Systematic Reviews search at www.thecochranelibrary.org is listed below:

2011 – NEW!

Boulias, C., Furlan, A.D., Gordon, A., Ismail, F., Sheean, G., & Waseem, Z.  (2011).  Botulinum toxin injections for low-back pain and sciatica.  Cochrane Database of Systematic Reviews, 2011, Issue 1.  Art. No.: CD008257. DOI: 10.1002/14651858.CD008257.pub2.
ID: CD008257
Available in full-text at:  http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD008257.pub2/epdf.  
ABSTRACT:  Background: Adequate relief from low-back pain (LBP) is not always possible. Emerging evidence suggests a role for botulinum neurotoxin (BoNT) injections in treating pain disorders. Proponents of BoNT suggest its properties can decrease muscle spasms, ischemia and inflammatory markers, thereby reducing pain.  Objectives: To determine the effects of botulinum toxin injections in adults with LBP.  Search methods: We searched CENTRAL (The Cochrane Library 2009, issue 3) and MEDLINE, EMBASE, and CINAHL to August 2009; screened references from included studies; consulted with content experts and Allergan. We included published and unpublished randomized controlled trials without language restrictions.  Selection criteria: We included randomized trials that evaluated BoNT serotypes versus other treatments in patients with non-specific LBP of any duration.  Data collection and analysis: Two review authors selected the studies, assessed the risk of bias using the Cochrane Back Review Group criteria, and extracted the data using standardized forms. We performed a qualitative analysis due to lack of data.  Main results: We excluded evidence from nineteen studies due to non-randomization, incomplete or unpublished data. We included three randomized trials (N =123 patients). Only one study included patients with chronic non-specific LBP; the other two examined unique subpopulations. Only one of the three trials had a low risk of bias and demonstrated that BoNT injections reduced pain at three and eight weeks and improved function at eight weeks better than saline injections. The second trial showed that BoNT injections were better than injections of corticosteroid plus lidocaine or placebo in patients with sciatica attributed to piriformis syndrome. The third trial concluded that BoNT injections were better than traditional acupuncture in patients with third lumbar transverse process syndrome. Both studies with high risk of bias had several key limitations. Heterogeneity of the studies prevented meta-analysis. There is low quality evidence that BoNT injections improved pain, function, or both better than saline injections and very low quality evidence that they were better than acupuncture or steroid injections.  Authors’ conclusions: We identified three studies that investigated the merits of BoNT for LBP, but only one had a low risk of bias and evaluated patients with non-specific LBP (N = 31). Further research is very likely to have an important impact on the estimate of effect and our confidence in it. Future trials should standardize patient populations, treatment protocols and comparison groups, enlist more participants and include long-term outcomes, cost-benefit analysis and clinical relevance of findings.

Documents from the Physiotherapy Evidence Database search at www.pedro.org.au are listed below:

2011 – NEW!

Byeon, G.J., & Kim, K.H.  (2011).  Piriformis syndrome in knee osteoarthritis patients after wearing rocker bottom shoes.  The Korean Journal of Pain, 24(2), 93-99.  
No abstract is available.

2009 – NEW!

Chen, R.N., & Chen, Y.B.  (2009).  Clinical observation on therapeutic effect and instant analgestic effect of inhibitory-needling at Ashi point as major point for treatment of piriformis syndrome.  [Chinese - simplified characters].  Zhongguo Zhen Jiu [Chinese Acupuncture & Moxibustion], 29(7), 550-55.  
No abstract is available.

2007 – NEW!

Bottrell, O., Campbell, H., Cramp, F., Ellyatt, P., Smith, C., & Wilde, B.  (2007).  Non-surgical management of piriformis syndrome:  A systematic review.  Physical Therapy Reviews, 12(1), 66-72.  
Available in full-text at:  http://www.crd.york.ac.uk/crdweb/ShowRecord.asp?AccessionNumber=12007009218&UserID=0.  
ABSTRACT:  The aim of this review was to identify and evaluate the evidence for the non-surgical management of Piriformis Syndrome. A systematic review of electronic databases was carried out up to February 2006. This was supplemented by hand searching journals and snow-bailing from reference lists. Strict inclusion/exclusion criteria were applied. Five independent observers reviewed the methodological quality of the core studies using the published Physiotherapy Evidence Database (PEDro) critique tool. Differences were resolved by consensus. Two studies met the inclusion/exclusion criteria. PEDro scores were 6/10 and 10/10. Both studies demonstrated positive effects for Botulinum toxin type A (Botox) injections compared to a placebo or control treatment. One study identified this positive effect in addition to a physiotherapy protocol. Evidence implies that Botox is a potentially successful treatment for Piriformis Syndrome; however, a paucity of high-quality clinical trials limits evidence of its overall efficacy. Further clinical trials of the effectiveness of non-surgical measures in the management of this syndrome are indicated.

2002 – NEW!

Anderson, C., Fishman, L.M., & Rosner, B.  (2002).  Botox and physical therapy in the treatment of piriformis syndrome.  American Journal of Physical Medicine & Rehabilitation, 81(12), 936-942.
ABSTRACT:  OBJECTIVE: This study evaluates the efficacy of Botulinum toxin A injections used in conjunction with physical therapy for the treatment of piriformis syndrome. DESIGN: This a double-blind, placebo controlled clinical trial using electrophysiologic criteria for patient selection and a visual analog scale to assess treatment efficacy in relieving pain. RESULTS: As measured on the visual analog scale, patients injected with Botulinum toxin A experienced more relief from pain than patients receiving lidocaine with steroid (p < 0.05) and more relief than patients receiving placebo (p = 0.001). CONCLUSIONS: Injection with Botulinum toxin A is an effective adjunct to physical therapy in the treatment of piriformis syndrome. H-reflex prolongation by flexion, adduction, and internal rotation (FAIR test) beyond 1.86 msec (3 SD) of the mean is a clinical indication of piriformis syndrome.

Documents from the National Library of Medicine PubMed search at www.pubmed.com are listed below:

2015 – NEW!

Abascal, F., Canga, A., Cerezal, L., Hernando, M.F., & Pérez-Carro, L.  (2015).  Deep gluteal syndrome: Anatomy, imaging, and management of sciatic nerve entrapments in the subgluteal space.  Skeletal Radiology, 44(7), 919-34.
PMID: 25739706  
ABSTRACT:  Deep gluteal syndrome (DGS) is an underdiagnosed entity characterized by pain and/or dysesthesias in the buttock area, hip or posterior thigh and/or radicular pain due to a non-discogenic sciatic nerve entrapment in the subgluteal space. Multiple pathologies have been incorporated in this all-included “piriformis syndrome,” a term that has nothing to do with the presence of fibrous bands, obturator internus/gemellus syndrome, quadratus femoris/ischiofemoral pathology, hamstring conditions, gluteal disorders and orthopedic causes. The concept of fibrous bands playing a role in causing symptoms related to sciatic nerve mobility and entrapment represents a radical change in the current diagnosis of and therapeutic approach to DGS. The development of periarticular hip endoscopy has led to an understanding of the pathophysiological mechanisms underlying piriformis syndrome, which has supported its further classification. A broad spectrum of known pathologies may be located nonspecifically in the subgluteal space and can therefore also trigger DGS. These can be classified as traumatic, iatrogenic, inflammatory/infectious, vascular, gynecologic and tumors/pseudo-tumors. Because of the ever-increasing use of advanced magnetic resonance neurography (MRN) techniques and the excellent outcomes of the new endoscopic treatment, radiologists must be aware of the anatomy and pathologic conditions of this space. MR imaging is the diagnostic procedure of choice for assessing DGS and may substantially influence the management of these patients. The infiltration test not only has a high diagnostic but also a therapeutic value. This article describes the subgluteal space anatomy, reviews known and new etiologies of DGS, and assesses the role of the radiologist in the diagnosis, treatment and postoperative evaluation of sciatic nerve entrapments, with emphasis on MR imaging and endoscopic correlation.

Akgün, U., Canbek, U., İmerci, A., Oztekin, H.H., & Zeren, B.  (2015).  Bilateral piriformis syndrome in two elite soccer players:  Report of two cases.  Orthopaedics & Traumatology, Surgery & Research (OTSR), 101(8), 987-90.
PMID: 26522381  
ABSTRACT:  Piriformis syndrome, a relatively rare condition, is described as entrapment of a sciatic nerve at the level of the piriformis muscle. There have been a few reports of bilateral piriformis syndrome in literature. In this study, we present bilateral piriformis syndrome in two professional soccer players from different teams who are symptom free at last follow-up after surgery. In both patients, resting EMG records were read normal, however EMG recording during the activity revealed prolonged H-reflexes. Both patients had no relief from conservative treatment and rehabilitation, therefore surgical treatment was performed. Preoperative mean visual analogue scale (VAS) value was 7, and decreased to 3 at the sixth month follow-up visit and at the longer term follow-up, mean 85 months (74-96) it was valued at 1. Both soccer players returned to their active sports lives in the sixth postoperative month. According to Benson’s functional evaluation scale, in long-term follow-up, there have been excellent results and both patients resumed their professional carrier for many years (mean 7 years).

Akgun, K., Erbilir, T., Erden, M.G., Misirlioglu, T.O., & Palamar, D.  (2015).  Piriformis syndrome:  Comparison of the effectiveness of local anesthetic and corticosteroid injections:  A double-blinded, randomized controlled study.  Pain Physician, 18(2), 163-71.
PMID: 25794202  
Available in full-text at:  http://www.painphysicianjournal.com/current/pdf?article=MjI2OA%3D%3D&journal=87.
ABSTRACT:  BACKGROUND: Piriformis syndrome (PS), which is characterized by pain radiating to the gluteal region and posterior leg, is accepted as one of the causes of sciatalgia. Although the importance of local piriformis muscle injections whenever PS is clinically suspected has been shown in many studies, there are not enough studies considering the clinical efficacy of these injections. OBJECTIVE: To investigate the differences between local anesthetic (LA) and LA + corticosteroid (CS) injections in the treatment of PS.  STUDY DESIGN: A prospective, double-blinded, randomized controlled trial. SETTING: Physical medicine and rehabilitation department of a university hospital. METHODS: Fifty-seven patients having unilateral hip and/or leg pain with positive FAIR test and tenderness and/or trigger point at the piriformis muscle were evaluated. Out of 50 patients randomly assigned to 2 groups, 47 patients whose pain resolved at least 50 percent from the baseline after the injection were diagnosed as having PS. The first group (n = 22) received 5 mL of lidocaine 2 percent while the second group (n = 25) received 4 mL of lidocaine 2 percent + 1 mL of betametazone under the guidance of ultrasound.  OUTCOME ASSESSMENT: Numeric Rating Scale (NRS) and Likert Analogue Scale (LAS).  RESULTS: No statistically significant difference (P > 0.05) was detected between the groups in NRS score values at resting (P = 0.814), night (P = 0.830), and in motion (P = 0.145), and LAS values with long duration of sitting (P = 0.547), standing (P = 0.898), and lying (P = 0.326) with evaluations at baseline, first week, and first and third months after the injection. A statistically highly significant (P < 0.005) reduction of pain was evaluated through NRS scores at resting (P = 0.001), in motion (P = 0.001), and at night (P = 0.001) and LAS values with long duration of sitting (P = 0.001), standing (P = 0.001), and lying (P = 0.001) in both of the groups.  LIMITATIONS: Presumed limitations of this study include having a relatively small sample.  CONCLUSION: LA injections for the PS were found to be clinically effective. However, addition of CS to LA did not give an additional benefit. This gives us the idea that PS is mostly muscular in origin and responds well to both LA and LA+CS injections.

Al-Al-Shaikh, M., Aubry, S., Kastler, B., Michel, F., Parratte, B., & Vidal, C.  (2015).  An MRI evaluation of changes in piriformis muscle morphology induced by botulinum toxin injections in the treatment of piriformis syndrome.  Diagnostic and Interventional Imaging, 96(1), 37-43.
PMID: 24703886  
Available in full-text at:  http://tinyurl.com/h9964rt.
ABSTRACT:  PURPOSE: Botulinum toxin (BT) injection is a new treatment for piriformis syndrome (PS). The main purpose of our study was to use MRI to evaluate changes in piriformis muscle morphology after treatment with BT injections.  PATIENTS AND METHODS: Twenty patients presenting with PS who had undergone an MRI were included retrospectively: 12 patients treated with BT injections and eight untreated patients. The following parameters were assessed and compared to a normal contralateral muscle: maximum thickness, volume, and Goutallier’s classification grade of fatty infiltration of the piriformis and internal obturator muscles. Pain was assessed through a visual analogue scale (VAS).  RESULTS: The untreated patients had no significant difference in the volume (P=1.0) or thickness of the piriformis muscle (P=0.61). The treated patients showed a significant reduction in the thickness (-4.2mm; P<0.001) and volume (-74.4mm (3); P<0.001) and an increase in the fatty infiltration (P<0.001) of the piriformis muscle treated by BT injection. Muscular atrophy was correlated with the number of BT injections and with the time until an MRI was performed. There was also significant pain relief after BT treatment.  CONCLUSION: BT leads to atrophy and fatty degeneration of the piriformis muscle that can be quantified by MRI and these factors explain why BT injections are effective in the treatment of PS.

Albayrak, A., Atici, Y., Balioglu, M.B., Ermis, M.N., Kargin, D., & Ozcafer, R.   (2015).  Piriformis syndrome:  Treatment of a rare cause of posterior hip pain with fluoroscopic-guided injection.  Hip International, 25(2), 172-5.
PMID: 25837782  
ABSTRACT:  INTRODUCTION: Piriformis syndrome involves the irritation of the piriformis muscle due to various reasons that are primarily related to anatomical variation or sciatic nerve compression due to contraction caused by overuse. In this study, we aimed to define an injection method that is easy to apply, safe, simple and repeatable.  MATERIALS AND METHODS: We administered percutaneous lidocaine and depomedrol injections into the hips of 28 patients (14 men and 14 women) under fluoroscopic control. Bipolar injections of the piriformis muscle were performed at the medial pole, the intersection of the sciatic notch and the sacroiliac joint, and at the lateral pole of the femoral insertion region. Each injection was 5 cc, and the contrast agent was observed after the dyeing process.  RESULTS: Clinical examinations were performed before and 6 weeks after the injections. The average of Harris Hip Score increased from a pre-injection score  of 44.5 to a post-injection score of 68.5, and the Visual Analog Scale scores decreased from 8.3 to 4.2 (p<0.05).  COMMENTS: Our findings lead to the conclusion that fluoroscopy-guided percutaneous local anaesthetic and corticosteroid injection is a simple and effective piriformis syndrome treatment that can feasibly be effectively performed by orthopaedic surgeons.

Beaulieu, C.F., Fredericson, M., Kraus, E., Ratliff, J., & Tenforde, A.S.  (2015).  Piriformis Syndrome with Variant Sciatic Nerve Anatomy: A Case Report.  PM & R:  The Journal of Injury, Function, and Rehabilitation, pii: S1934-1482(15)00994-6. doi: 10.1016/j.pmrj.2015.09.005. [Epub ahead of print]
PMID: 26377629  
ABSTRACT:  A 68-year-old male long distance runner presented with low back and left buttock pain, which eventually progressed to severe and debilitating pain, intermittently radiating to the posterior thigh and foot. A comprehensive workup ruled out possible spine or hip causes of his symptoms. A pelvic magnetic resonance imaging neurogram with complex oblique planes through the piriformis demonstrated variant anatomy of the left sciatic nerve consistent with the clinical diagnosis of piriformis syndrome. The patient ultimately underwent neurolysis with release of the sciatic nerve and partial resection of the piriformis muscle. After surgery the patient reported significant pain reduction and resumed running three months later. Piriformis syndrome is uncommon but should be considered in the differential diagnosis for buttock pain. Advanced imaging was essential to guide management.

Bhattad, S.B., Gupta, A., Sharma, D., Singh, S., Sinha, A., & Suri, D.  (2015).  Piriformis Syndrome in a Young Child:  An Unusual Clinical Entity.  Indian Journal of Pediatrics, 2015 Aug 21. [Epub ahead of print].
PMID: 26289660
No abstract is available.  

Byrd, J.W.  (2015).  Disorders of the Peritrochanteric and Deep Gluteal Space: New Frontiers for Arthroscopy.  Sports Medicine and Arthroscopy Review, 23(4), 221-31.
PMID: 26524558  
ABSTRACT:  Arthroscopic techniques for the hip joint have evolved into endoscopic methods for extra-articular disorders. These endoscopic strategies provide a less invasive alternative to open procedures for traditionally recognized forms of pathology. Endoscopy has defined new disorders amenable to surgical correction and has redefined some of these existing disorders. The peritrochanteric and deep gluteal regions represent two of the most currently active areas of exploration. Peritrochanteric problems include trochanteric bursitis, full-thickness and partial-thickness tears of the abductors including the gluteus medius and minimus, and external coxa saltans (snapping iliotibial band). Deep gluteal disorders include piriformis syndrome, and other variations of deep gluteal syndrome, and ischiofemoral impingement. Each of these evolving areas is highlighted in this chapter.

Cass, S.P.  (2015).  Piriformis syndrome:  A cause of nondiscogenic sciatica.  Current Sports Medicine Reports, 14(1), 41-4. doi: 10.1249/JSR.0000000000000110.
PMID: 25574881  
ABSTRACT:  Piriformis syndrome is a nondiscogenic cause of sciatica from compression of the sciatic nerve through or around the piriformis muscle. Patients typically have sciatica, buttocks pain, and worse pain with sitting. They usually have normal neurological examination results and negative straight leg raising test results.  Flexion, adduction, and internal rotation of the hip, Freiberg sign, Pace sign, and direct palpation of the piriformis cause pain and may reproduce symptoms. Imaging and neurodiagnostic studies are typically normal and are used to rule out other etiologies for sciatica. Conservative treatment, including medication and physiotherapy, is usually helpful for the majority of patients. For recalcitrant cases, corticosteroid and botulinum toxin injections may be attempted. Ultrasound and other imaging modalities likely improve accuracy of injections. Piriformis tenotomy and decompression of the sciatic nerve can be done for those who do not respond.

Drampalos, E., Lomax, A., Paul, A., Sadiq, M., & Thompson, T.  (2015).  Intrapiriformis lipoma:  An unusual cause of piriformis syndrome.  European Spine Journal, 24 Suppl 4, S551-4.  
PMID: 25424688  
ABSTRACT:  INTRODUCTION: We report on a patient with an unusual cause of non-discogenic sciatica. MATERIAL AND METHODS: A 48-year-old woman presented with a 10-day history of gradually worsening left buttock pain radiating to the ipsilateral posterior thigh and calf. She had a similar episode of less intense pain 8 months before which lasted about 2 months. She denied any history of antecedent trauma or back pain. MRI scan revealed a well-defined, fat-containing lesion of the left piriformis muscle similar to a lipoma displacing the sciatic nerve but not invading it. The sciatica was relieved after excision of the lesion. The patient remained asymptomatic after the operation. CONCLUSION: The present case suggested that an intrapiriformis lipoma can cause secondary piriformis syndrome and medical practitioners should be aware of this condition and consider lipomas and other occupying lesions of the pelvic muscles as a differential diagnosis in patients presenting with radicular pain.

Guler, T., Gunduz, O.H., Misirlioglu, T.O., Ozer, T., & Yıldırım, P.  (2015).  A case of drop foot due to piriformis syndrome.  Acta Neurologica Belgica, 115(4), 847-9.
PMID: 25676003  
No abstract is available.

Jeong, H.S., Joe, E.G., Kang, H.S., Lee, E.G., Lee, G.Y., & Lee, J.W.  (2015).  Long-term assessment of clinical outcomes of ultrasound-guided steroid injections in patients with piriformis syndrome.  Ultrasonography, 34(3), 206-10.
PMID: 25672769
Available in full-text at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4484286/pdf/usg-14039.pdf.  
ABSTRACT:  PURPOSE: The purpose of this study was to evaluate the long-term efficacy of ultrasound (US)-guided steroid injections in patients with piriformis syndrome. METHODS: Between January 2010 and October 2012, 63 patients (23 men and 40 women; average age, 63.2 years; range, 24 to 90 years) were diagnosed with piriformis syndrome based on clinical history, electromyography, and flexion-adduction-internal rotation test results. They were divided into two groups. The first group (37 subjects) received a US-guided steroid injection around the piriformis muscle. The second group (26 subjects) received both piriformis muscle and spinal epidural injections. The therapeutic effect was categorized as improvement, partial improvement, or failure depending on the degree of symptom alleviation one month after injection, based on a review of each patient’s medical records. RESULTS: In the first group, 15 patients (40.5 percent) showed improvement, seven (18.9 percent) showed partial improvement, and 15 (40.5 percent) failed to respond to the initial treatment. In the second group, eight patients (30.8 percent) showed improvement, 11 (42.3 percent) showed partial improvement, and seven (26.9 percent) failed to respond to the initial treatment. A second piriformis injection was performed in four cases, after which two patients showed improvement within three years, but the other two showed no therapeutic effect. CONCLUSION: US-guided steroid injection may be an effective treatment option for patients with piriformis syndrome.

2014 – NEW!

Arooj, S., & Azeemuddin, M.  (2014).  Piriformis syndrome:  A rare cause of extraspinal sciatica.  Journal of the Pakistan Medical Association, 64(8), 949-51.
PMID: 25252525  
Available in full-text at:  http://jpma.org.pk/PdfDownload/6894.pdf.  
ABSTRACT:  Piriformis syndrome is a rare entity resulting in severe unilateral isolated buttock pain shooting in nature, non discogenic in origin. MR imaging of pelvis plays an important role in such patients to see the normal anatomy of piriformis muscle and its relationship with sciatic nerve. A 35-year-old woman presented with one year history of radiating leg pain with normal MR lumbosacral spine. MRI pelvis showed an abnormal orientation of left sciatic nerve through cleaved fibers of the piriformis muscle. The patient’s symptoms were relieved by surgical decompression. The purpose of this case report is to show the role and importance of MR imaging for tracing sciatic nerve and its relationship to the Piriformis muscle. MR imaging of pelvis for sciatic nerve plays an important role in symptomatic patients with isolated buttock pain having normal MRI lumbosacral spine.

Asensio-Samper, J.M., De Andrés, J., Eichenberger, U., Fabregat, G., Martínez-Sanjuan, V., Roselló, M., & Villaneuva-Pérez, V.L.  (2014).  Computer-tomographic verification of ultrasound-guided piriformis muscle injection:  A feasibility study.  Pain Physician, 17(6), 507-13.  
PMID: 25415775  
Available in full-text:  http://www.painphysicianjournal.com/current/pdf?article=MjE5MA%3D%3D&journal=85.
ABSTRACT:  BACKGROUND: Approximately 6 to 8 percent of lumbar pain cases, whether associated with radicular pain or not, may be attributed to the presence of piriformis muscle syndrome. Available treatments, among others, include pharmacotherapy, physical therapy, and injections of different substances into the muscle. Various methods have been used to confirm correct needle placement during these procedures, including electromyography (EMG), fluoroscopy, computed tomography (CT), or magnetic resonance imaging (MRI). Ultrasonography (US) has now become a widely used technique and therefore may be an attractive alternative for needle guidance when injecting this muscle. OBJECTIVE: The objective of this study was to assess the reliability of US in piriformis injection of patients with piriformis syndrome. STUDY DESIGN: Feasibility study; 10 patients with piriformis muscle syndrome were injected with botulinum toxin A using a US-guided procedure. Then patients were administered 2 mL iodinated contrast and were then transferred to the CT scanner, where they underwent pelvic and hip imaging to assess intramuscular distribution of the iodinated contrast. SETTING: Multidisciplinary Pain Management Department in Spain. RESULTS: Of all 10 study patients (8 women, 2 men), 9 had intramuscular or intrafascial contrast distribution. Distribution did not go deeper than the piriformis muscle in any of the patients. The absence of contrast (intravascular injection) was not observed in any case. LIMITATIONS: The main limitation of our study is the use of ionizing radiation as confirmation technique. CONCLUSION: Ultrasound-guided puncture may be a reliable and simple procedure for injection of the piriformis muscle, as long as good education and training are provided to the operator. US has a number of advantages over traditional approaches, including accessibility and especially no ionizing radiation exposure for both health care providers and patients.

Aytekin, A., Develi, S., Ekinci, S., & Parlak, A.  (2014).  Piriformis syndrome:  A case with non-discogenic sciatalgia.  Turkish Neurosurgery, 24(1), 117-9.
PMID: 24535806  
Available in full-text at:  http://www.turkishneurosurgery.org.tr/pdf/pdf_JTN_1267.pdf.  
ABSTRACT:  Piriformis syndrome is a clinical picture of non-discogenic sciatica caused by compression of the sciatic nerve by the piriformis muscle. It has variable etiologies and the patho-physiology is not fully understood. The major etiology was known to be the spasm, edema and inflammation of the piriformis muscle and sciatic nerve compression of the muscle later on. Patients can be diagnosed immediately with a comprehensive clinical examination and early diagnosis makes the treatment much easier. Diagnosis of the piriformis syndrome, a very rare cause of low back pain, first requires that this syndrome is remembered, and then a differential diagnosis should be performed. A case of piriformis syndrome diagnosed in a patient who presented with low back pain is reported in this study.

Baxter, B., Gulledge, B.M., Harrysson, O.L., Levine, D., Marcellin-Little, D.J., Osborne, J.A., & Tillman, L.  (2014).  Comparison of two stretching methods and optimization of stretching protocol for the piriformis muscle.  Medical Engineering & Physics, 36(2), 212-8.
PMID: 24262799  
ABSTRACT:  Piriformis syndrome is an uncommon diagnosis for a non-discogenic form of sciatica whose treatment has traditionally focused on stretching the piriformis muscle (PiM). Conventional stretches include hip flexion, adduction, and external rotation. Using three-dimensional modeling, we quantified the amount of (PiM) elongation resulting from two conventional stretches and we investigated by use of a computational model alternate stretching protocols that would optimize PiM stretching. Seven subjects underwent three CT scans: one supine, one with hip flexion, adduction then external rotation (ADD stretch), and one with hip flexion, external rotation then adduction (ExR stretch). Three-dimensional bone models were constructed from the CT scans. PiM elongation during these stretches, femoral neck inclination, femoral head anteversion, and trochanteric anteversion were measured. A computer program was developed to map PiM length over a range of hip joint positions and was validated against the measured scans. ExR and ADD stretches elongated the PiM similarly by approximately 12 percent. Femoral head and greater trochanter anteversion influenced PiM elongation. Placing the hip joints  in 115° of hip flexion, 40° of external rotation and 25° of adduction or 120° of  hip flexion, 50° of external rotation and 30° of adduction increased PiM elongation by 30-40 percent compared to conventional stretches (15.1 and 15.3 percent increases in PiM muscle length, respectively). ExR and ADD stretches elongate the PiM similarly and therefore may have similar clinical effectiveness. The optimized stretches led to larger increases in PiM length and may be more easily performed by some patients due to increased hip flexion.

Dauty, M., Dubois, C., Fouasson-Chaillou, A., & Menu, P.  (2014). Piriformis syndrome diagnosis:  On two professional cyclists.  Annals of Physical and Rehabilitation Medicine, 57(4), 268-74.
PMID: 24731941
Available in full-text at:  http://tinyurl.com/zuw7unp.
No abstract is available.  

Denk, C.C., Gundogmus, B., Ozisik, P.A., Taskiran, O.O., & Toru, M.  (2014).  CT-guided piriformis muscle injection for the treatment of piriformis syndrome.  Turkish Neurosurgery, 24(4), 471-7.
PMID: 25050669  
Available in full-text at:  http://www.turkishneurosurgery.org.tr/pdf/pdf_JTN_1356.pdf.  
ABSTRACT:  AIM: Piriformis syndrome is a rare neuromuscular disorder that occurs when the piriformis muscle compresses or irritates the sciatic nerve. The treatment of piriformis syndrome includes injections into the piriformis muscle around the sciatic nerve. These invasive approaches have been used with various techniques to increase the safety of the procedure. Computed tomography (CT)-guided injection of the piriformis muscle and the clinical outcome of the patients are discussed. MATERIAL AND METHODS: The authors presented 10 consecutive patients that underwent CT-guided piriformis injection between March and December 2007. Three patients had a history of a severe fall on the buttocks, one had gluteal abscess formation following deep intramuscular injection, and another one had a habit of prolonged sitting on the carpet. Etiology was not identified in the other patients. Main complaints of the patients were pain and numbness in the legs. Hypesthesia was the major neurological finding. Magnetic resonance imaging (MRI) and electromyography (EMG) were performed in all patients. RESULTS: Nine patients had full and sustained recovery of their symptoms after piriformis injection. Only the patient who had gluteal abscess formation following deep intramuscular injection showed moderate improvement. Another patient was operated on in the 6th month after piriformis injection due to an extruded disc herniation. CONCLUSION: CT-guided piriformis injection is a safe and effective method in the treatment of piriformis syndrome.

Fowler, I.M., Mendez, R.J., Moran, T.J., Tucker, A.A., & Weimerskirch, B.P.  (2014).  A randomized comparison of the efficacy of two techniques for piriformis muscle injection:  Ultrasound-guided versus nerve stimulator with fluoroscopic guidance.  Regional Anesthesia and Pain Medicine, 39(2), 126-32.  
PMID: 24509422  
ABSTRACT:  BACKGROUND: Piriformis muscle injections are most often performed using fluoroscopic guidance; however, ultrasound (US) guidance has recently been described extensively in the literature. No direct comparisons between the two techniques have been performed. Our objective was to compare the efficacy and efficiency of fluoroscopic- and US-guided techniques. METHODS: A randomized, comparative trial was carried out to compare the two techniques. Twenty-eight patients with a diagnosis of piriformis syndrome, based on history and physical examination, who had failed conservative treatment were enrolled in the study. Patients were randomized to receive the injection either via US or fluoroscopy. Injections consisted of 10 mL of 1 percent lidocaine with 80 mg of triamcinalone. The primary outcome measure was numeric pain score, and secondary outcome measures included functional status as measured by the Multidimensional Pain Inventory, patient satisfaction as measured by the Patient Global Impression of Change scale, and procedure timing characteristics. Outcome data were measured preprocedure, immediately postprocedure, and 1 to 2 weeks and 3 months postprocedure. RESULTS: We found no statistically significant differences in numeric pain scores, patient satisfaction, procedure timing characteristics, or most functional outcomes when comparing the two techniques. Statistically significant differences between the two techniques were found with respect to the outcome measures of household chores and outdoor work. CONCLUSIONS: Ultrasound-guided piriformis injections provide similar outcomes to fluoroscopically guided injections without differences in imaging, needling, or overall procedural times.

Khasru, M.R., Rasker, J.J., & Siddiq, M.A.  (2014).  Piriformis syndrome in fibromyalgia:  Clinical diagnosis and successful treatment.  Case Reports in Rheumatology, doi: 10.1155/2014/893836. Epub 2014 Sep 22.
PMID: 25328750  
Available in full-text at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4190119/pdf/CRIRH2014-893836.pdf.  
ABSTRACT:  Piriformis syndrome is an underdiagnosed extraspinal association of sciatica.
Patients usually complain of deep seated gluteal pain. In severe cases the clinical features of piriformis syndrome are primarily due to spasm of the piriformis muscle and irritation of the underlying sciatic nerve but this mysterious clinical scenario is also described in lumbar spinal canal stenosis, leg length discrepancy, piriformis myofascial pain syndrome, following vaginal delivery, and anomalous piriformis muscle or sciatic nerve. In this paper, we describe piriformis and fibromyalgia syndrome in a 30-year-old young lady, an often missed diagnosis. We also focus on management of the piriformis syndrome.

Koebke, J., Konstantinidis, G.A., Natsis, K., Paraskevas, G., Piagkou, M., & Totlis, T.  (2014).  Anatomical variations between the sciatic nerve and the piriformis muscle:  A contribution to surgical anatomy in piriformis syndrome.  Surgical and Radiologic Anatomy, 36(3), 273-80.
PMID: 23900507  
PURPOSE: To detect the variable relationship between sciatic nerve and piriformis muscle and make surgeons aware of certain anatomical features of each variation that may be useful for the surgical treatment of the piriformis syndrome. METHODS: The gluteal region of 147 Caucasian cadavers (294 limbs) was dissected.  The anatomical relationship between the sciatic nerve and the piriformis muscle was recorded and classified according to the Beaton and Anson classification. The literature was reviewed to summarize the incidence of each variation. RESULTS: The sciatic nerve and piriformis muscle relationship followed the typical anatomical pattern in 275 limbs (93.6 percent). In 12 limbs (4.1 percent) the common peroneal nerve passed through and the tibial nerve below a double piriformis.  In one limb (0.3 percent) the common peroneal nerve coursed superior and the tibial nerve below the piriformis. In one limb (0.3 percent) both nerves penetrated the piriformis.  In one limb (0.3 percent) both nerves passed above the piriformis. Four limbs (1.4 percent) presented non-classified anatomical variations. When a double piriformis muscle was present, two different arrangements of the two heads were observed. CONCLUSIONS: Anatomical variations of the sciatic nerve around the piriformis muscle were present in 6.4 percent of the limbs examined. When dissection of the entire piriformis is necessary for adequate sciatic nerve decompression, the surgeon should explore for the possible existence of a second tendon, which may be found either inferior or deep to the first one. Some rare, unclassified variations of the sciatic nerve should be expected during surgical intervention of the region.

Yin, G.L., Wang, F.  (2014).  Warm acupuncture combined with muscle strength technique for 46 cases of piriformis syndrome.  [Article in Chinese].  Chinese Acupuncture & Moxibustion, 34(4), 407-8.
PMID: 24946654  
No abstract is available.

2013 – NEW!

Benrath, J., Blunk, J.A., Nowotny, M., & Scharf, J.  (2013).  MRI verification of ultrasound-guided infiltrations of local anesthetics into the piriformis muscle.  Pain Medicine, 14(10), 1593-9.
PMID: 23758696  
Available in full-text at:  http://painmedicine.oxfordjournals.org/content/painmedicine/14/10/1593.full.pdf.
ABSTRACT:  OBJECTIVE: Patients presenting with buttock pain syndromes are common. Up to eight percent of these conditions may be attributed to piriformis syndrome. Included in several therapeutic and diagnostic approaches, injections directly into the piriformis muscle may be performed. Because the muscle lies very close to neurovascular structures, electromyographic, fluoroscopic, computed tomographic, and magnetic resonance imaging (MRI) guidance have been employed. In few studies, an ultrasound-guided technique was used to inject a local anesthetic into the piriformis muscle without impairing adjacent neuronal structures. DESIGN: Feasibility study in healthy human subjects. Confirmation of ultrasound-guided injections by MRI. SUBJECTS: In 10 male human subjects, ultrasound-guided injections of 3 mL of a local anesthetic into the piriformis muscle were performed. METHODS: Directly after the injection, the subjects were placed in an MRI scanner, and the placement of the liquid depot was confirmed by MRI imaging. Somatosensory deficits were evaluated after the injection. RESULTS: The MRI showed that 9 of 10 of the injections were correctly placed within the piriformis muscle. The distance of the depot to the sciatic nerve decreased over time due to dispersion, but the nerve itself was not reached in the MRI. Only one subject experienced slight, short-term sensorimotor deficits. CONCLUSIONS: MRI confirmed the correct placement of the local anesthetic within the muscle. The dispersion of the fluid 30 minutes after the injection could be visualized. Moreover, only one subject experienced slight motor deficits without anatomical correlate. This ultrasound-guided method will be further employed in ongoing clinical studies.

Candler, S.A., Clendenen, S.R., Duench, S., Ghazi, S.M., Glynn, L., Osborne, M.D., & Palmer, S.C.  (2013).  Needle placement for piriformis injection using 3-D imaging.  Pain Physician, 16(3), E301-10.
PMID: 23703429  
Available in full-text at:  http://www.painphysicianjournal.com/current/pdf?article=MTkyNQ%3D%3D&journal=75.  
ABSTRACT:  Piriformis syndrome is a pain syndrome originating in the buttock and is attributed to 6 to 8 percent of patients referred for the treatment of back and leg pain. The treatment for piriformis syndrome using fluoroscopy, computed tomography (CT), electromyography (EMG), and ultrasound (US) has become standard practice. The treatment of Piriformis Syndrome has evolved to include fluoroscopy and EMG with CT guidance. We present a case study of five successful piriformis injections using 3-D computer-assisted electromagnet needle tracking coupled with ultrasound. A 6-degree of freedom electromagnetic position tracker was attached to the ultrasound probe that allowed the system to detect the position and orientation of the probe in the magnetic field. The tracked ultrasound probe was used to find the posterior superior iliac spine. Subsequently, three points were captured to register the ultrasound image with the CT or magnetic resonance image scan. Moreover, after the registration was obtained, the navigation system visualized the tracked needle relative to the CT scan in real-time using two orthogonal multi-planar reconstructions centered at the tracked needle tip. Conversely, a recent study revealed that fluoroscopically guided injections had 30 percent accuracy compared to ultrasound guided injections, which tripled the accuracy percentage. This novel technique exhibited an accurate needle guidance injection precision of 98 percent while advancing to the piriformis muscle and avoiding the sciatic nerve. The mean (± SD) procedure time was 19.08 (± 4.9) minutes. This technique allows for electromagnetic instrument tip tracking with real-time 3-D guidance to the selected target. As with any new technique, a learning curve is expected; however, this technique could offer an alternative, minimizing radiation exposure.

Chen, C.K., & Nizar, A.J.  (2013).  Prevalence of piriformis syndrome in chronic low back pain patients. A clinical diagnosis with modified FAIR test.  Pain Practice, 13(4), 276-81.
PMID: 22863240  
ABSTRACT:  PURPOSE: Piriformis syndrome is a collection of symptoms and signs of pain from piriformis muscle and is characterized by pain in buttock with variable involvement of sciatic nerve. This syndrome is often overlooked in clinical practice because its presentation has similarities with other spine pathologies.  A major problem with the clinical diagnosis of piriformis syndrome is the lack of consistent objective findings and an absence of single test that is specific for piriformis syndrome. Therefore, a precise and reliable clinical method of diagnosing piriformis syndrome should be developed by clinicians. METHODS: This is a prospective observational study involving 93 consecutive patients who attended the pain management unit for chronic low back pain. The diagnosis of piriformis syndrome was made using the modified flexion adduction internal rotation (FAIR) test, which is a combination of Lasègue sign and FAIR test. Prevalence of piriformis syndrome based on this technique was compared with the previous data using other techniques. Chi square (χ2) analysis was performed to detect the relationship between piriformis syndrome and the potential risk factors. RESULTS: On the basics of our diagnostic criteria, the prevalence of piriformis syndrome was 17.2 percent among low back pain patients. All the patients diagnosed with piriformis syndrome responded well with piriformis muscle injections. No significant associations were detected between piriformis syndrome and spine disorders. CONCLUSIONS: Piriformis syndrome is a painful condition that is often overlooked in the differential diagnosis of chronic buttock or low back pain. The modified FAIR test together with piriformis muscle injection is potentially a reliable method for the clinical diagnosis of piriformis syndrome.

Chen, S., Fan, Y., Li, H.T., Liu, J.M., Qi, F.J., Tian, J.G., & Tian, W.H.  (2013).  Observation on therapeutic effect of round-sharp needle of new nine-needle and elongated needle for piriformis syndrome with triple puncture method.  [Article in Chinese].  Chinese Acupuncture & Moxibustion, 33(5), 422-5.
PMID: 23885616  
ABSTRACT:  OBJECTIVE: To compare the efficacy differences between round-sharp needle of new nine-needle and elongated needle for piriformis syndrome, and explore its action mechanism. METHODS: Eighty cases were randomly divided into a round-sharp needle of new nine-needle group (round-sharp needle group) and an elongated needle treatment group (elongated needle group), 40 cases in each group. The round-sharp needle group was treated with round-sharp needle (0.60 mm x 125 mm) at three points in piriformis with triple puncture method, while the elongated needle group was treated with elongated needle of ordinary specifications (0.32 mm x 125 mm) at three points in piriformis with triple puncture method. Besides, the two groups were also treated with routine acupuncture at Weizhong (BL 40) and Yanglingquan (GB 34), 3 times every week, 2 weeks as one course of treatment. After one course of treatment, the clinical effect was evaluated and the pain threshold values were measured before and after treatment in the two groups. RESULTS: The total effective rate in the round-sharp needle group was 92.5 percent (37/40), which was superior to 77.5 percent (31/40) in the elongated needle group (P < 0.05). Compared before treatment, the pain threshold values after treatment in two groups were improved significantly (both P < 0.01). The increment of pain threshold value in the round-sharp needle group was higher than that in the elongated needle group (P < 0.01). CONCLUSION: Round-sharp needle of new nine-needle is effective in treatment of piriformis syndrome and is better than ordinary elongated needle, which is related to that it can effectively increase pain threshold value of the local tissue.

Delabie, A., Foulon, P., Havet, E., Le Gars, D., Page, C., & Peltier, J.  (2013).  Relationships between piriformis muscle and sciatic nerve:  Radioanatomical study with 104 buttocks.  [Article in French].  Morphologie, 97(316), 12-8.
PMID: 23414787  
ABSTRACT:  OBJECTIVE: The relationships between the piriformis muscle and the sciatic nerve are close and may be changing. In some cases, these relationships are the cause of a piriformis syndrome, an under-diagnosed etiology of non discal sciatica. The aim of the study was to explore, by the MRI, the sciatic nerve and the piriformis muscle. MATERIELS AND METHODS: One hundred and four buttocks were explored by MRI for 52 randomly selected patients. RESULTS: In 59.6 percent of cases, no variation of the piriformis muscle and sciatic nerve were found. In 26 percent of cases, the sciatic nerve was divided into the pelvis. In 9.6 percent of cases, it was divided into the pelvis, the piriformis muscle was bifid and the common peroneal nerve ran between both heads. The piriformis muscle was bifid in 10.6 percent of cases, hypertrophic in 13.5 percent of cases and atrophic in 2.9 percent of cases.

Jankovic, D., Peng, P., & van Zundert, A.  (2013).  Brief review:  Piriformis syndrome: etiology, diagnosis, and management.  Canadian Journal of Anaesthesia, 60(10), 1003-12.
PMID: 23893704  
Available in full-text at:  http://tinyurl.com/jf8vhfs.  
ABSTRACT:  PURPOSE: In this narrative review, we aim to provide the pathophysiology and diagnostic criteria of the piriformis syndrome (PS), an underdiagnosed cause of buttock and leg pain that can be difficult to treat. Based on existing evidence, frequencies of clinical features are estimated in patients reported to have PS. In view of the increasing popularity of ultrasound for intervention, the ultrasound-guided technique in the treatment of PS is described in detail. SOURCE: A literature search of the MEDLINE® database was performed from January 1980 to December 2012 using the search terms e.g., “ piriformis injection”, “ ultrasound guided piriformis injection”, “ botulinum toxin”, “pain management”, and different structures relevant in this review. There was no restriction on language. PRINCIPAL FINDINGS: A review of the medical literature pertaining to PS revealed that the existence of this entity remains controversial. There is no definitive proof of its existence despite reported series with large numbers of patients. CONCLUSION: Piriformis syndrome continues to be a controversial diagnosis for sciatic pain. Electrophysiological testing and nerve blocks play important roles when the diagnosis is uncertain. Injection of local anesthetics, steroids, and botulinum toxin into the piriformis muscle can serve both diagnostic and therapeutic purposes. An ultrasound-guided injection technique offers improved accuracy in locating the piriformis muscle. Optimizing the therapeutic approach requires an interdisciplinary evaluation of treatment.

Koda, M., Murakami, K., Murakami, M., Nakajima, A., Nakajima, H., Rokkaku, T., Toda, T., Watanabe, H., & Yamada, T.  (2013).  Sciatica caused by pyomyositis of the piriformis muscle in a pediatric patient.  Orthopedics, 36(2), e257-9.
PMID: 23383745  
Available in full-text at:  http://tinyurl.com/hsyr9jx.  
ABSTRACT:  Because the sciatic nerve leaves the pelvis through the greater sciatic notch underneath the piriformis muscle, any pathology of the piriformis muscle could result in entrapment of the sciatic nerve; this is widely known as piriformis muscle syndrome. Pyomyositis of the piriformis muscle may be a cause of piriformis muscle syndrome. Piriformis muscle syndrome caused by pyomyositis of the piriformis muscle in pediatric patients is rare. This article describes a case of sciatica caused by pyomyositis of the piriformis muscle in a pediatric patient. A 6-year-old boy presented with right buttock and thigh pain following a mild fever and sore throat. The pain worsened, and he became unable to walk. On admission, his temperature was 38.4°C. He reported severe right-sided buttock and lateral thigh pain. Positive Freiberg sign was observed. Laboratory examination revealed elevated white blood cell count and C-reactive protein level. T2-weighted magnetic resonance images of the pelvis revealed high-intensity changes of the piriformis muscle and iliosacral joint. Thus, piriformis syndrome caused by pyomyositis of the piriformis muscle was diagnosed. Oral antibiotics (10 mg/kg per day of cefdinir) were administered. Pain gradually decreased, and the patient was able to walk. Final follow-up examination at 6 months after symptom onset revealed no sciatic pain. Follow-up magnetic resonance imaging revealed normalized intensities of the piriformis muscle. The endopelvic fascia provides a route for infection from the pelvis to the piriformis. The pyomyositis of the piriformis muscle in the current case may have occurred secondary to the pyoarthritis of the sacroiliac joint. Endopelvic infections involving the piriformis muscle may mimic hip diseases in pediatric patients.

Mutlu, H., Ozyurek, S., Sivrioglu, A.K., & Sonmez, G.  (2013).  Piriformis syndrome occurring after pregnancy.  BMJ Case Reports, 2013. pii: bcr2013008946. doi: 10.1136/bcr-2013-008946.
PMID: 23536625  
Available in full-text at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3618849/pdf/bcr-2013-008946.pdf.  
No abstract is available. 

2012 – NEW!

Bakkum, B.W., & Chapman, C.  (2012).  Chiropractic management of a US Army veteran with low back pain and piriformis syndrome complicated by an anatomical anomaly of the piriformis muscle:  A case study.  Journal of Chiropractic Medicine, 11(1), 24-9.
PMID: 22942838  
Available in full-text at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3315859/pdf/main.pdf.  
ABSTRACT:  OBJECTIVE: The purpose of this article is to present the case of a patient with an anatomical anomaly of the piriformis muscle who had a piriformis syndrome and was managed with chiropractic care.  CASE REPORT: A 32-year-old male patient presented to a chiropractic clinic with a chief complaint of low back pain that radiated into his right buttock, right posterior thigh, and right posterior calf. The complaint began 5 years prior as a result of injuries during Airborne School in the US Army resulting in a 60 percent disability rating from the Veterans Administration. Magnetic resonance imaging demonstrated a mildly decreased intradiscal T2 signal with shallow central subligamentous disk displacement and low-grade facet arthropathy at L5/S1, a hypolordotic lumbar curvature, and accessory superior bundles of the right piriformis muscle without morphologic magnetic resonance imaging evidence of piriformis syndrome.  INTERVENTION AND OUTCOME: Chiropractic treatment included lumbar and sacral spinal manipulation with soft tissue massage to associated musculature and home exercise recommendations. Variations from routine care included proprioceptive neuromuscular facilitation stretches, electric muscle stimulation, acupressure point stimulation, Sacro Occipital Technique pelvic blocking, CranioSacral therapy, and an ergonomic evaluation.  CONCLUSION: A patient with a piriformis anomaly with symptoms of low back pain and piriformis syndrome responded positively to conservative chiropractic care, although the underlying cause of the piriformis syndrome remained.

Bubb, K., Cassidy, L., Loukas, M., Shoja, M.M., Tubbs, R.S., & Walters, A.  (2012).  Piriformis syndrome:  Implications of anatomical variations, diagnostic techniques, and treatment options.  Surgical and Radiologic Anatomy (SRA), 34(6), 479-86.
PMID: 22327640  
ABSTRACT:  Details of piriformis syndrome, including the proper diagnosis and most effective form of treatment, continue to be controversial. While the cause, diagnosis, and treatment of piriformis syndrome remain elusive, many studies have been conducted to investigate newly developed diagnostic techniques as well as various treatment options for piriformis-induced sciatica. Despite the quantity of literature, few studies have demonstrated statistically significant results that support one form of treatment over another. Thus, despite the evidence supporting the newer treatment methodologies for piriformis syndrome, research should continue. It is important not only to evaluate treatment outcomes based on associated pain relief, but also to investigate the functional and anatomical return that patients experience from these studied treatments in order to fully explore the most effective form of therapy for piriformis syndrome.

Calabria, E., Crusco, S., Masala, S., Meschini, A., Simonetti, G., & Taglieri, A.  (2012).  Piriformis syndrome:  Long-term follow-up in patients treated with percutaneous injection of anesthetic and corticosteroid under CT guidance.  Cardiovascular and Interventional Radiology, 35(2), 375-82.
PMID: 21607823  
ABSTRACT:  PURPOSE: This study was designed to evaluate the efficacy of CT-guided injection of anesthetic and corticosteroid for the treatment of pain in patients with piriformis syndrome unresponsive to conservative treatment. METHODS: We enrolled 23 patients with piriformis syndrome, proposing a percutaneous intramuscular injection of methylprednisone-lidocaine. Among them, 13 patients accepted and 10 refused to undergo the procedure; the second group was used as a control group. Clinical evaluation was performed with four maneuvers (Lasègue sign, FAIR test, Beatty and Freiberg maneuver) and a VAS questionnaire before the injection, after 5-7 days, and after 2 months. A telephonic follow-up was conducted to 3, 6, and 12 months. RESULTS: Procedural success was achieved in all patients who were treated without any complications. After 2 months, among 13 treated subjects, 2 of 13 patients showed positivity to FAIR test (hip flexion, adduction, and internal rotation), 2 of 13 were positive to Lasègue sign, and the Beatty maneuver was positive in 1 patient. Patients who underwent conservative treatment were positive respectively in 7 of 10 (p = 0.01), 6 of 10 (p = 0.03), and 6 of 10 (p = 0.01). The VAS score showed a difference between patients treated with percutaneous approach and those managed with conservative therapy at the baseline evaluation (p = 0.04), after 2 months (p = 0.02), and 12 months (p = 0.002). We observed a significant reduction in pain for patients treated percutaneously, who were evaluated with the VAS scale at 5-7 days, 2 months, 3, 6, and 12 months (p < 0.001). CONCLUSIONS: Our findings suggested potential benefit from the percutaneous injection of anesthetics and corticosteroids under CT guidance for the treatment of piriformis syndrome.

Grossman, G.E., Justice, P.E., Katirji, B., & Preston, D.C.  (2012).  Piriformis syndrome surgery causing severe sciatic nerve injury.  Journal of Clinical Neuromuscular Disease, 14(1), 45-7.
PMID: 22922582  
ABSTRACT:  Piriformis syndrome is a controversial entrapment neuropathy in which the sciatic nerve is thought to be compressed by the piriformis muscle. Two patients developed severe left sciatic neuropathy after piriformis muscle release. One had a total sciatic nerve lesion, whereas the second had a predominantly high common peroneal nerve lesion. Follow-up studies showed reinnervation of the hamstrings only. We conclude that piriformis muscle surgery may be hazardous and result in devastating sciatic nerve injury.

Kitagawa, Y., Takai, S., Tamai, K., & Yokoyama, M.  (2012).  Chronic expanding hematoma extending over multiple gluteal muscles associated with piriformis syndrome.  Journal of Nippon Medical School, 79(6), 478-83.
PMID: 23291848  
Available in full-text at:  https://www.jstage.jst.go.jp/article/jnms/79/6/79_478/_pdf.  
ABSTRACT:  We report on a patient with an unusual, slowly enlarging hematoma of the left buttock. A 62-year-old man presented with a 6-year history of an enlarging mass of the left buttock. He had first noted the mass 6 years earlier and had had sciatica of the left lower limb for the last 2 months. He denied any history of antecedent trauma. The lesion extended over 3 gluteal muscles (the gluteus medius, gluteus minimus, and piriformis). On microscopic examination, the lesion showed typical signs of chronic expanding hematoma. The sciatica was relieved after surgical removal of the lesion. The lesion had not recurred at the last follow-up 4 years after the operation. The present case suggested that chronic expanding hematoma can extend into multiple muscles due, perhaps, to long-term growth and the anatomical and functional conditions of the affected muscles. Our case also suggests that chronic expanding hematoma can be a cause of piriformis syndrome.

Miller, T.A., Ross, D.C., & White, K.P.  (2012).  The diagnosis and management of piriformis syndrome:  Myths and facts.  The Canadian Journal of Neurological Sciences, 39(5), 577-83.
PMID: 22931697  
ABSTRACT:  Piriformis syndrome (PS) is an uncommon, controversial neuromuscular disorder that is presumed to be a compression neuropathy of the sciatic nerve at the level of the piriformis muscle (PM). The diagnosis is hampered by a lack of agreed upon clinical criteria and a lack of definitive investigations such as imaging or electrodiagnostic testing. Treatment has focused on stretching, physical therapies, local injections, including botulinum toxin, and surgical management.  This article explores the various sources of controversy surrounding piriformis syndrome including diagnosis, investigation and management. We conclude with a proposal for diagnostic criteria which include signs and symptoms, imaging, and response to therapeutic injections.

2011 – NEW!

Burger, E.L., Cooley, R., Estes, S., Gonzalez, P., Lindley, E.M., Patel, V.V., & Robinson, E.S.  (2011).  Piriformis syndrome versus radiculopathy following lumbar artificial disc replacement.  Spine, 36(4), E282-7.
PMID: 21270711  
ABSTRACT:  STUDY DESIGN: Case series. OBJECTIVE: To describe the presentation, diagnostic challenges, and treatment of five patients with piriformis syndrome after lumbar artificial disc replacement. SUMMARY OF BACKGROUND DATA: Until recently, spinal fusion was considered the standard for surgical treatment of severe lumbar degenerative disc disease. However, artificial disc replacement now offers an alternative solution. Piriformis syndrome results from entrapment of the sciatic nerve at the greater sciatic notch, with symptoms of pain and numbness radiating from the buttock to the foot, mimicking radiculopathy. METHODS: In this case series, we report five patients who developed piriformis at our institution after artificial disc replacement. RESULTS: Five patients, aged 35 to 46 years, developed some or all of the following symptoms in the affected leg after artificial disc replacement: posterior leg and buttock pain, calf weakness, and toe and ball of foot numbness and tingling. The onset of symptoms ranged from 6 days to 8 months postoperative, and became debilitating over time. Each patient was diagnosed with piriformis syndrome through physical examination. Three of the patients received a piriformis injection and reported 50 percent to 100 percent pain relief lasting 1 to 3 weeks. The patients subsequently underwent physical therapy that provided relief of their piriformis syndrome-related pain and enabled them to resume their normal activities. CONCLUSION: Piriformis syndrome has not previously been described in the literature as a sequela of lumbar artificial disc replacement. Our case series indicates that this complication may be underdiagnosed. Careful consideration after artificial disc replacement is required if the patient presents with buttock, leg or foot pain, and/or numbness. It is important for physicians to recognize the symptoms of piriformis syndrome and to differentiate piriformis syndrome from nerve root compression and irritation or referred pain from spinal structures. Although controversial, the proper diagnosis of piriformis syndrome may have prevented some of these patients from undergoing unnecessary surgical procedures.

2010 – NEW!

Assoum, H.A., Jawish, R.M., & Khamis, C.F.  (2010).  Anatomical, clinical, and electrical observations in piriformis syndrome.  Journal of Orthopaedic Surgery and Research, 5, 3. doi: 10.1186/1749-799X-5-3.
PMID: 20180984
Available in full-text at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2828977/pdf/1749-799X-5-3.pdf.
ABSTRACT:  BACKGROUND: We provided clinical and electrical descriptions of the piriformis syndrome, contributing to better understanding of the pathogenesis and further diagnostic criteria. METHODS: Between 3550 patients complaining of sciatica, we concluded 26 cases of piriformis syndrome, 15 females, 11 males, mean age 35.37 year-old. We operated 9 patients, 2 to 19 years after the onset of symptoms, 5 had piriformis steroids injection. A dorsolumbar MRI were performed in all cases and a pelvic MRI in 7 patients. The electro-diagnostic test was performed in 13 cases, between them the H reflex of the peroneal nerve was tested 7 times. RESULTS: After a follow-up 1 to 11 years, for the 17 non operated patients, 3 patients responded to conservative treatment. 6 of the operated had an excellent result, 2 residual minor pain and one failed. 3 new anatomical observations were described with atypical compression of the sciatic nerve by the piriformis muscle. CONCLUSION: While the H reflex test of the tibial nerve did not give common satisfaction in the literature for diagnosis, the H reflex of the peroneal nerve  should be given more importance, because it demonstrated in our study more specific sign, with six clinical criteria it contributed to improve the method of diagnosis. The cause of this particular syndrome does not only depend on the relation sciatic nerve-piriformis muscle, but the environmental conditions should be considered with the series of the anatomical anomalies to explain the real cause of this pain.

Beltran, J., Beltran, L.S., Bencardino, J., & Ghazikhanian, V.  (2010).  Entrapment neuropathies III:  Lower limb.  Seminars in Musculoskeletal Radiology, 14(5), 501-11.
PMID: 21072728  
ABSTRACT:  Clinicians frequently encounter compressive neuropathies of the lower extremity.
The clinical history and physical examination, along with electrodiagnostic testing and imaging studies, lead to the correct diagnosis. The imaging characteristics of the compression neuropathies can include acute and chronic changes in the nerves and the muscles they innervate. We provide a detailed review of compression neuropathies of the lower extremity with an emphasis on magnetic resonance (MR) imaging characteristics. We discuss the clinical presentation, etiology, anatomical location, and MR imaging appearance of these neuropathies, including the piriformis syndrome, iliacus syndrome, saphenous neuropathy, obturator neuropathy, lateral femoral cutaneous neuropathy (meralgia paresthetica), proximal tibial neuropathy, common peroneal neuropathy, deep peroneal neuropathy, superficial peroneal neuropathy, tarsal tunnel syndrome, Baxter’s neuropathy, jogger’s foot, sural neuropathy, and Morton’s neuroma.

Dye, J.A., Farrokhi, S., Kochevar, R.J., Powers, C.M., Tonley, J.C., & Yun, S.M.  (2010).  Treatment of an individual with piriformis syndrome focusing on hip muscle strengthening and movement reeducation:  A case report.  The Journal of Orthopaedic and Sports Physical Therapy, 40(2), 103-11.
PMID: 20118521  
Available in full-text at:  http://www.jospt.org/doi/pdf/10.2519/jospt.2010.3108.  
ABSTRACT:  STUDY DESIGN: Case report. OBJECTIVE: To describe an alternative treatment approach for piriformis syndrome using a hip muscle strengthening program with movement reeducation. BACKGROUND: Interventions for piriformis syndrome typically consist of stretching and/or soft tissue massage to the piriformis muscle. The premise underlying this approach is that a shortening or “spasm” of the piriformis is responsible for the compression placed upon the sciatic nerve. CASE DESCRIPTION: The patient was a 30-year-old male with right buttock and posterior thigh pain for 2 years. Clinical findings upon examination included reproduction of symptoms with palpation and stretching of the piriformis. Movement analysis during a single-limb step-down revealed excessive hip adduction and internal rotation, which reproduced his symptoms. Strength assessment revealed weakness of the right hip abductor and external rotator muscles. The patient’s treatment was limited to hip-strengthening exercises and movement reeducation to correct the excessive hip adduction and internal rotation during functional tasks. OUTCOMES: Following the intervention, the patient reported 0/10 pain with all activities. The initial Lower Extremity Functional Scale questionnaire score of 65/80 improved to 80/80. Lower extremity kinematics for peak hip adduction and internal rotation improved from 15.9 degrees and 12.8 degrees to 5.8 degrees and 5.9 degrees, respectively, during a step-down task. DISCUSSION: This case highlights an alternative view of the pathomechanics of piriformis syndrome (overstretching as opposed to overshortening) and illustrates the need for functional movement analysis as part of the examination of these patients. LEVEL OF EVIDENCE: Therapy, level 4.

Han, Y.J., Jeon, S.Y., Moon, H.S., & Sung, C.H.  (2010).  Post-radiation piriformis syndrome in a cervical cancer patient:  A case report.  The Korean Journal of Pain, 23(1), 88-91.
PMID: 20552082  
Available in full-text at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2884211/pdf/kjp-23-88.pdf.  
ABSTRACT:  The piriformis syndrome is a condition allegedly attributable to compression of the sciatic nerve by the piriformis muscle. Recently, magnetic resonance neurography and electrophysiologic study have helped to diagnose piriformis syndrome. High dose radiotherapy could induce acute and delayed muscle damage. We had experienced piriformis syndrome with fatty atrophy of piriformis muscle after radiotherapy for recurrent cervical cancer.

Kallitsis, E.A., Kanakis, D.N., Lazaris, A.C., Papadopoulos, E.C., Paraskevakou, H.A., & Patsouris, E.S.  (2010).  Piriformis syndrome:  An attempt to understand its pathology.  Clinical Neuropathology, 29(2), 65-70.
PMID: 20175954  
ABSTRACT:  OBJECTIVE: Gross anatomy of the hip rotators and histology of the sciatic nerves in adult cadavers were studied, aiming to the identification of possible pathologic changes related to the piriformis syndrome (PS). MATERIAL: 50 cadavers were dissected; in 17 cases with macroscopical findings the sciatic nerves were harvested (34 sciatic nerves; 17 cadavers). History of low back or leg pain was not available. METHOD: Site anatomy and additional findings at the harvesting sites were recorded, such as anatomical variations, adhesions, hematomas etc. All nerves were additionally microscopically analyzed. In cases with findings at the dissection, the contralateral unaffected nerves served as controls. All the dissected nerves were conserved in 10 percent formalin solution, embedded in paraffin, stained with Hematoxylin and Eosin (H&E) and immunolabeled with antibodies against Neurofilament (NF). RESULTS: Both the H&E staining as well as the performed immunohistochemistry showed, to a variable degree, significant alterations in the structure of the affected nerves compared to the controls. CONCLUSIONS: These findings both in the local anatomy and sciatic nerve correspond to lesions that are expected in PS. Nevertheless, since this was a cadaveric study, unassociated to a certain pain patient’s history, results should be considered and interpreted as an indication of a sciatic nerve injury in PS.

2009 – NEW!

Akbas, M., Dere, K., & Luleci, N.  (2009).  A rare cause of a piriformis syndrome.  Journal of Back and Musculoskeletal Rehabilitation, 22(1), 55-8.
PMID: 20023365  
Available in full-text at:  http://tinyurl.com/z6a786e.  
ABSTRACT:  BACKGROUND AND OBJECTIVE: A less common but important cause of buttock and leg pain known as “Piriformis Syndrome”. Piriformis syndrome is all intrinsic pathology of the piriformis itself, such as myofascial pain, anatomical variations, hypertrophy, and myositis ossificans or it is caused by trauma to the pelvis or buttock. In this case report we are going to present a rare cause of piriformis syndrome. CASE REPORT: Our first case was a 32 year old woman. She was referred to our pain clinic for leg pain that radiates from buttock to backside of the knee for five years. She did not have any problems in her history or laboratory findings. But in her lower extremity ortho roentgenogram, her leg was 2 cm short at the effected side. Second case was a 23 year old woman who had pain radiating from gluteal region to backside of the knee. In her history she had a car accident two years ago. In this accident, she had a fracture of collum femoris, and her leg was 1 cm short at the effected side. CONCLUSION: We conclude that “short leg” is one of the rare causes of piriformis syndrome and can be seen alone or with the other causes. The injection on piriformis muscle could be more effective for the patients who have PS after the “short leg” treated.

Al-Tannir, M., Daher, Y., El-Rajab, M., Khatib, H., Naja, Z., Tayara, K., & Ziade, F.  (2009). The effectiveness of clonidine-bupivacaine repeated nerve stimulator-guided injection in piriformis syndrome.  The Clinical Journal of Pain, 25(3), 199-205.
PMID: 19333169  
ABSTRACT:  OBJECTIVES: Piriformis syndrome (PS) is often refractory to conventional therapies. Guided injection techniques generally necessitate a computed tomography or fluoroscopic guidance that may not be available in most pain management centers in addition to its relative high cost. The aim of this clinical trial is to investigate whether clonidine-bupivacaine nerve-stimulator guided injections are effective in achieving long-lasting pain relief in PS compared with bupivacaine guided injection. METHODS: A pilot study conducted on 18 patients (15 females, 3 males) diagnosed with PS showed the adequacy of nerve stimulator guided technique assessed via confirmatory visualized tomography scan demonstrating a worthy coverage of the piriformis muscle in about 84 percent of the cases. This randomized double-blind trial included 80 patients with PS who received a nerve stimulator-guided piriformis injection (group C received 9 mL bupivacaine 0.5 percent and 1 mL clonidine 150 mcg/mL;  group B received 9 mL bupivacaine 0.5 percent and 1 mL saline). Pain characteristics and analgesics consumption were the primary end points assessed for 6 months. RESULTS: Group C showed significantly lower pain scores and analgesics consumption than group B (P<0.0001). Pain at 6 months was significantly greater in group B (78 percent) than in group C (8 percent) (P<0.01). For every 18 months of PS pain, the outcomes demonstrated that a patient needed 1 additional injection to the initial injection. DISCUSSION: Repeated clonidine-guided piriformis injection relieved PS symptoms and reduce analgesic consumption for a 6-month period. It is a cost-effective useful treatment for PS refractory to traditional therapeutic approaches.

Cole, J.L., Foye, P.M., & Kirschner, J.S.  (2009).  Piriformis syndrome, diagnosis and treatment.  Muscle Nerve, 40(1), 10-8.
PMID: 19466717  
ABSTRACT:  Piriformis syndrome (PS) is an uncommon cause of sciatica that involves buttock pain referred to the leg. Diagnosis is often difficult, and it is one of exclusion due to few validated and standardized diagnostic tests. Treatment for PS has historically focused on stretching and physical therapy modalities with refractory patients also receiving anesthetic and corticosteroid injections into the piriformis muscle origin, belly, muscle sheath, or sciatic nerve sheath. Recently, the use of botulinum toxin (BTX) to treat PS has gained popularity. Its use is aimed at relieving sciatic nerve compression and inherent muscle pain from a tight piriformis. BTX is being used increasingly for myofascial pain syndromes, and some studies have demonstrated superior efficacy to corticosteroid injection. The success of BTX in treating PS supports the prevailing pathoanatomic etiology of the condition and suggests a promising future for BTX in the treatment of other myofascial pain syndromes.   

Chen, R.N., & Chen, Y.B.  (2009).  Clinical observation on therapeutic effect and instant analgestic effect of inhibitory-needling at Ashi point as major point for treatment of piriformis syndrome.  [Article in Chinese].  Chinese Acupuncture & Moxibustion, 29(7), 550-2.
PMID: 19835123  
ABSTRACT:  OBJECTIVE: To observe therapeutic effect and analgesic eJfect of needling at Ashi point for treatment of piriformis syndrome. METHODS: Eighty cases were randomly divided into an inhibitory-needling method group (INM) and a routine-needling method group (RNM), forty cases in each group. The acupuncture at Ashi point as major point with inhibitory-needling munipulation was applied in the INM group, the acupuncture at Huantiao (GB 30) ,Zhibian (BL 54) ,Yanglingquan (GB 34) with routine-needling method in the RNM group. The therapeutic effect, the instant analgesic effect and score of Visual Analogue Scale (VAS) were observed. RESULTS: After treatment, the effective rate of 92.5 percent in the INM group was better than that of 82.5 percent in the RNM group (P < 0.05); the instant analgesic effect rate of 75.0 percent in the INM group was better than that of 52.5 percent in the RNM group (P < 0.01); the score of VAS in both groups had decreased with a significant difference between two groups (P < 0.05). CONCLUSION: The treatment of inserting the needle at Ashi point as major point with inhibitory-needling method has excellent effectiveness and good instant analgesic effect, with fewer point(s) selection and rapid effect.

Ganju, A., & Halpin, R.J.  (2009).  Piriformis syndrome:  A real pain in the buttock?  Neurosurgery, 65(4 Suppl), A197-202.
PMID: 19927068  
ABSTRACT:  OBJECTIVE: Herein, we provide an unbiased review of piriformis syndrome (PS), a highly controversial syndrome for which no consensus exists regarding diagnostic criteria or pathophysiology. METHODS: A review of the literature in the English language. RESULTS: A nonpartisan review of the medical literature pertaining to PS revealed that the existence of this entity remains controversial. There is no definitive proof of its existence despite reported series with large numbers of patients. CONCLUSION: PS remains a controversial diagnosis for sciatic pain. The debate regarding the clinical significance of PS remains active. Nonetheless, there may be a subset of patients in whom the piriformis muscle is a source of pain. The syndrome should be considered in the differential diagnosis of patients with unilateral lower extremity pain.

Zou, Z.  (2009).  Fifty-two cases of the piriformis syndrome treated by centro-square needling.  Journal of Traditional Chinese Medicine, 29(1), 11-2.
PMID: 19514181  
Full-text is available at:  http://www.journaltcm.com/modules/Journal/contents/stories/091/4.pdf.
No abstract is available.

2008 – NEW!

Alonso, J., de Dios, B.J, Redondo, M.V., Reus, M., & Vázquez, V.  (2008).  Piriformis syndrome:  A simple technique for US-guided infiltration of the perisciatic nerve.  Preliminary results.  European Radiology, 18(3), 616-20.
PMID: 17972081  
ABSTRACT:  The piriformis syndrome is an uncommon cause of sciatica, buttock or thigh pain.
Because of the deep location of the muscle and sciatic nerve, infiltration has traditionally been guided by electromyography, fluoroscopy, computed tomography or magnetic resonance imaging. The aim of the present study is to describe a simple technique for ultrasound (US)-guided perisciatic infiltration of corticosteroids and anaesthetic using the inferior gluteal artery as a landmark. This technique was used satisfactorily in ten patients. Although the series in the study is limited, the procedure for US-guided infiltration of the perisciatic nerve is a quick, simple, economical and effective technique and can be considered an alternative in the percutaneous treatment of the piriformis syndrome.

Boyajian-O’Neill, L.A., Coleman, M.K., McClain, R.L., & Thomas, P.P.  (2008).  Diagnosis and management of piriformis syndrome:  An osteopathic approach.  Journal of the American Osteopathic Association, 108(11), 657-64.
PMID: 19011229  
Available in full-text at:  http://jaoa.org/article.aspx?articleid=2093614.  
ABSTRACT:  Piriformis syndrome is a neuromuscular condition characterized by hip and buttock pain. This syndrome is often overlooked in clinical settings because its presentation may be similar to that of lumbar radiculopathy, primary sacral dysfunction, or innominate dysfunction. The ability to recognize piriformis syndrome requires an understanding of the structure and function of the piriformis muscle and its relationship to the sciatic nerve. The authors review the anatomic and clinical features of this condition, summarizing the osteopathic medical approach to diagnosis and management. A holistic approach to diagnosis requires a thorough neurologic history and physical assessment of the patient based on the pathologic characteristics of piriformis syndrome. The authors note that several nonpharmacologic therapies, including osteopathic manipulative treatment, can be used alone or in conjunction with pharmacotherapeutic options in the management of piriformis syndrome.

Filler, A.G.  (2008).  Piriformis and related entrapment syndromes:  Diagnosis & management.  Neurosurgery Clinics of North America, 19(4), 609-22.  
PMID: 19010285  
ABSTRACT:  Highly reliable evidence for piriformis syndrome and other pelvic sciatic syndromes arises from three major categories of data: magnetic resonance neurography diagnostic imaging, open magnetic resonance-guided injection studies, and patient treatment outcome studies. This article reviews the evidence in each category. This is part of a Point-Counterpoint discussion with Dr. Robert Tiel’s presentation of “Myth and Fallacy”.

Gruen, G.S., Kobbe, P., & Zelle, B.A.  (2008).  Case report:  Recurrent piriformis syndrome after surgical release.  Clinical Orthopaedics and Related Research, 466(7), 1745-8.
PMID: 18264837  
Available in full-text at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2505267/pdf/11999_2008_Article_151.pdf.  
ABSTRACT:  Piriformis syndrome is an uncommon condition characterized by sciatic nerve entrapment at the greater sciatic notch. Nonoperative treatment such as physical therapy, nonsteroidal antiinflammatory drugs, and local injections often results in relief of symptoms. For patients who do not benefit from nonoperative therapy, surgical exploration and decompression of the sciatic nerve has been effective. However, the success of surgery may be diminished by scar formation or hematoma in the anatomically restricted sciatic notch. We report two patients with piriformis syndrome who responded primarily to surgical decompression and had recurrent symptoms resulting from scar tissue formation in the sciatic notch. On revision surgery, polytetrafluoroethylene pledgets were placed around the sciatic nerve to avoid compression and entrapment by scar tissue. Both patients had satisfactory outcomes at three year follow-up.

Tiel, R.L.  (2008).  Piriformis and related entrapment syndromes:  Myth & fallacy.  Neurosurgery Clinics of North America, 19(4), 623-7.  
PMID: 19010286  
This article explores the myths surrounding piriformis syndrome. It looks at the syndrome’s history ranging from early hypothesis to acceptance; then from disfavor to resurrection as a diagnosis for patients with leg pain devoid of objective neurologic deficits, without disc herniations. It includes a critical review of the clinical literature and treatment strategies. It calls for a renaming of the syndrome to “nonlocalizing sciatica” and restriction of surgical resection of the piriformis to cases where all other treatment has failed. This is part of a Point-Counterpoint discussion with Dr. Aaron Filler’s presentation of “Diagnosis and Management”.

2007 – NEW!

Anderhuber, F., Braun, E.M., & Windisch, G.  (2007).  Piriformis muscle:  Clinical anatomy and consideration of the piriformis syndrome.  Surgical and Radiologic Anatomy (SRA), 29(1), 37-45.
PMID: 17216293  
ABSTRACT:  Patients with lumbosacral and buttock pain provide tacit support for recognizing the piriformis muscle as a contributing factor to the pain (piriformis syndrome). One hundred and twelve cadaveric specimens were observed to elucidate the anatomical variations of the piriformis muscle referred to the diagnostic and treatment of the piriformis syndrome. The distance between the musculotendinous junction and the insertion was measured and the piriformis categorized into three types: Type A (71, 63.39 percent): long upper and short lower muscle belly; Type B (40, 35.71 percent): short upper and long lower muscle belly; Type C (1, 0.9 percent): fusion of both muscle bellies at the same level. The diameter of the piriformis tendon at the level of the musculotendinous junction ranged from 3 to 9 mm (mean: 6.3 mm).  The piriformis showed the following possible fusions with adjacent tendons. In type one (60, 53.57 percent) a rounded tendon of the piriformis reached the upper border of the greater trochanter. In type two (33, 29.46 percent) it first joined into the gemellus superior tendon and at last both fused with the obturator internus tendon and inserted into the medial surface of the greater trochanter. A fusion of the piriformis, obturator internus and gluteus medius tendon with the same insertion area as above was observed in type three (15, 13.39 percent) and finally in type four (4, 3.57 percent) the tendon fused with the gluteus medius to reach the upper surface of the greater trochanter. Based on this survey anatomical causes for the piriformis syndrome are rare and a more precise workup is necessary to rule out more common diagnosis.

Ho, J., Kang, H.Y., Kim, K.I., Lee, S.H., Oh, J.M., Shin, W.G., & Yoon, S.J.  (2007).  Low-dose botulinum toxin type A for the treatment of refractory piriformis syndrome.  Pharmacotherapy, 27(5), 657-65.
PMID: 17461700  
ABSTRACT:  STUDY OBJECTIVES: To evaluate the efficacy of a single, low-dose injection of botulinum toxin type A in relieving pain in Korean patients with piriformis syndrome resistant to conventional therapy, and to assess the drug’s influence on these patients’ quality of life. DESIGN: Prospective, single-site, open-label trial. SETTING: Rehabilitation medicine clinic in Seoul, Korea. PATIENTS: Twenty-nine patients with a confirmed diagnosis of chronic piriformis syndrome and 82 age- and sex-matched healthy subjects were enrolled from April 1, 2003-February 28, 2004. Intervention. In 20 of the patients, botulinum toxin type A 150 U was injected using computed tomographic guidance into the affected unilateral piriformis muscle. The other nine patients served as active controls and received an injection of dexamethasone 5 mg and 1 percent lidocaine. The healthy subjects did not receive any injection.  MEASUREMENTS AND MAIN RESULTS: The patients’ pain at baseline and at 4, 8, and 12 weeks after treatment was rated by using a numeric rating scale. Health-related quality of life was assessed by using the validated Korean version of the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) at baseline and at 4 weeks of treatment. Healthy subjects also completed the SF-36 at baseline. Pain intensity scores were significantly lower at 4, 8, and 12 weeks after treatment than at baseline (p<0.0001). Baseline scores from the SF-36 subscales, including those for physical functioning (p<0.0001), role physical (p<0.0001), bodily pain (p<0.0001), general health (p<0.0001), vitality (p<0.0001), and social functioning (p<0.002), were significantly lower in the patients than in the healthy subjects. Four weeks after treatment, physical functioning (p=0.003), role physical (p=0.021), bodily pain (p=0.016), general health (p=0.013), vitality (p=0.031) and social functioning (p=0.035) improved significantly from baseline in the patients. However, at 4 weeks, patients in the active control group were withdrawn from the study because their pain did not improve, and continuation without further medical care was considered unethical. CONCLUSION: A low dose of botulinum toxin type A relieved pain and improved quality of life in patients with refractory piriformis syndrome.


Descarreaux, M., Fortin, J., Mayrand, N., & Normand, M.C.  (2006).  Diagnosis and management of posttraumatic piriformis syndrome:  A case study.  Journal of Manipulative and Physiological Therapeutics, 29(6), 486-91.
PMID: 16904496  
ABSTRACT:  OBJECTIVE: The aim of this study is to describe the clinical management of a young male patient with sciatica symptoms that developed after an avulsion of the ischial tuberosity. This is a rare injury, but complications may occur. CLINICAL FEATURE: A 19-year-old patient developed sciatica 6 months after a football injury. The patient described his symptoms as a shooting pain from the buttock to the lateral part of the foot, along the back of his thigh and calf, sometimes accompanied by paresthesia. Physical examination showed restricted hip range of motion and a positive Bonnet’s test. X-ray analysis revealed a bony overgrowth of the right ischial tuberosity. INTERVENTION AND OUTCOME: A treatment plan was designed to decrease the pain level, increase sacroiliac and lumbar joint mobility, and augment muscular extensibility. The patient received 20 treatments over a period of approximately 3 months. Complete recovery was observed 5 months later. CONCLUSION: Although many differential diagnoses were contemplated, it is most likely that changes in muscular tension and gait pattern, resulting from the ischial tuberosity avulsion, contributed to overuse of the piriformis muscle leading to a piriformis syndrome.

Quick Looks

Online Resources Related to Piriformis Syndrome

Piriformis syndrome (PS) is a rare neuromuscular disorder that occurs when the piriformis muscle compresses or irritates the sciatic nerve causing pain, tingling, and numbness in the buttocks and along the path of the sciatic nerve descending into the lowering thigh and into the leg.  Unfortunately, there are little to no support/organizational resources for individuals experiencing this syndrome.  However, there are various informational websites that provide an overview of PS, detail the condition, and offer suggestions for treatment and/or exercises.  

As always, we provide these resources as a service to our patrons but strongly recommend consulting with a medical professional before attempting any self-treatment or exercises on your own.  

5 Things to Know About the Piriformis Stretch from Healthline.com

Find an Orthopaedist Through the American Academy/Association of Orthopaedic Surgeons

Google Video Search Results for Exercises for Piriformis Syndrome

How Can I Banish That Pain in My Butt? in Runner’s World at RunnersWorld.com

Information about Diagnosis and Treatment of Piriformis Syndrome from Orthopedics.about.com

Move Forward by the American Physical Therapy Association
Find a Physical Therapist:  aptaapps.apta.org/findapt/index.aspx.  

National Center for Complementary and Integrative Health (NCCIH)
Toll Free:  888/644-6226 (V), 866/464-3615 (TTY)
Pain Information Page:  nccih.nih.gov/health/pain.

National Center on Health, Physical Activity, and Disability (NCHPAD)
An information center concerned with physical activity and disability.
Toll Free: 800/900-8086 (V/TTY)
NCPAD Program Database:  www.nchpad.org/Directories/Programs.
NCPAD Parks Database:  www.nchpad.org/Directories/Parks.
NCPAD Personal Trainers Database:  www.nchpad.org/Directories/19/Personal~Trainers.
NCPAD Factsheets on Exercise and Fitness:  www.nchpad.org/Articles.

Physical Medicine and Rehabilitation for Piriformis Syndrome from Medscape.com

Piriformis Syndrome: How to Detect It and Strengthening and Stretching Programs to Help You Heal on RunnersConnect.net

Piriformis Syndrome Information at SportsInjuryClinic.net

Piriformis Syndrome Information Sheet from TherapeuticAssociates.com
Includes diagrams for exercises to help PS and to strengthen the piriformis muscle

Piriformis Syndrome from Physiopedia.com
Includes videos, diagrams for stretches and maneuvers

Piriformis Syndrome: A Royal Pain in the Butt on MultiBriefs.com (Video Included)

Piriformis Syndrome from WebMD Pain Management Health Center

Stretches and Exercise for Sciatic Pain from Piriformis Syndrome from Spine-Health.com
Includes video and diagrams for stretches and maneuvers

What is Piriformis Syndrome? on Spine-Health.com

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About reSearch:

reSearch is a new information product from the National Rehabilitation Information Center (NARIC). Each issue is based on real-world queries received by our information specialists from researchers, educators, and rehabilitation professionals around the world.

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