What is Locked-in Syndrome?

In an article in the International Encyclopedia of Rehabilitation, a definition of Locked-in Syndrome (LIS) is credited to the American Congress of Rehabilitation Medicine (ACRM) and it defined LIS, in 1995, as a "syndrome characterized by preserved awareness, relatively intact cognitive functions, and by the ability to communicate while being paralysed (sic) and voiceless." Five criteria define LIS:

  1. Sustained eye opening and preserved vertical eye movement,
  2. Preserved higher cortical functions,
  3. Aphonia or severe hypophonia,
  4. Quadriplegia or quadriparesis, and
  5. Primary mode of communication that uses vertical eye movements or blinking.

LIS is a rare neurological disorder and leaves individuals completely mute and paralyzed. This syndrome can be caused by a lesion to the brainstem. LIS can also be caused by traumatic brain injury, diseases of the circulatory system, diseases that destroy the myelin sheath surrounding nerve cells, or medication overdose.

Currently, there is no cure for LIS and there is no standard course of treatment. However, there are treatments such as functional neuromuscular stimulation (which uses electrodes to stimulate muscle reflexes and may help activate some paralyzed muscles). Other treatments are supportive and deal with certain symptoms. There are devices available that help people with LIS to communicate. Check with Abledata to see what is available.

Is research being done?

The National Institute of Neurological Disorders and Stroke (NINDS) currently supports research on neurological disorders that can cause LIS with the goal of finding ways to prevent, treat, and cure these disorders. There are no clinical trials at NINDS at this time; however, check their page on clinical trials frequently.

We searched through our publications and found reSearch Volume 1, Issue 4A which looks at LIS in a more detailed form. We also searched REHABDATA and found several articles on LIS and related disorders. Here are just a few of the articles we found:

  • A case study of locked-in-syndrome: Psychological and personal perspectives. NARIC Accession Number: J61596.
  • A network approach to assessing cognition in disorders of consciousness. NARIC Accession Number: J62915.
  • Neurospsychologic assessment and cognitive rehabilitation in a patient with locked-in syndrome and left neglect. NARIC Accession Number: J58367.

For more information, you can visit NINDS, the International Encyclopedia of Rehabilitation, or you can conduct searches in our Knowledgebase, in REHABDATA, or the NIDILRR Program Directory.