Locked-in syndrome is a rare phenomenon which makes conscious people almost entirely unable to move and communicate. It is estimated there are fewer than 1,000 existing cases in the US, and between 50 and 300 in the UK.
In some instances, locked-in syndrome paralyses all muscles. In others, some muscles escape paralysis and can act as a means of communication. The muscles surrounding the eye can still function in most locked-in patients, for example, so they may be able to move their eyes in different directions or blink their eyelids. In 2024, Howard Wicks completed a 50,000-word novel using specialist eye-gazing technology, despite being entirely paralysed by a stroke in 2011.
Brainstem strokes are a principal cause of locked-in syndrome, but there are others. Sometimes it can arise as a result of brain injury, or from nerve damage by a growing brain tumour. Motor neurone disease, or amyotrophic lateral sclerosis (ALS), may also in its later stages cause whole-body paralysis.
