What is Locked-In Syndrome?
Locked-in syndrome is a rare neurological condition characterised by paralysis of all the muscles, except the ones that control eye movement. People who have locked-in syndrome are conscious, but appear to be in a coma-like state, which can last for months or even several years. With locked-in syndrome, communication is possible through movement of the eyes, but people are unable to speak or move.
Disorders that are similar or related to locked-in syndrome include:
- Akinetic mutism: this rare disorder is characterised by a lack of movement or speech even though the individual is awake. It is most commonly caused by traumatic damage affecting the grey matter.
- Guillain-Barre syndrome
- myasthenia gravis
- bilateral brain tumours
What causes locked-in syndrome?
Locked-in syndrome is caused by damage to the pons, which is part of the brainstem. The pons contains very important neurological pathways that carry information from the brain to the spinal cord and the muscles. When the pons is damaged, the signals are disrupted and this results in paralysis, loss of speech and facial muscle movement. The most common cause of damage to the pons is disrupted blood flow to the brain, known as infarction. This can result from strokes and thrombosis. Less commonly, locked-in syndrome can be associated with trauma, tumours, nerve inflammation and damage to the myelin, the protective white matter. Some neurological disorders, such as ALS (amyotrophic lateral sclerosis), may also damage the pons.
Who is affected?
Locked-in syndrome is rare. It affects both males and females and may occur in children and adults. Most cases are diagnosed in adults who have a higher risk of haemorrhages or strokes.
What are the symptoms?
Locked-in syndrome causes a coma-like state, but the individual is conscious. Symptoms include:
- no ability to chew
- loss of speech
- movement in the eyes only (often this relates to moving the eyes up and down, not side to side)
- communication through blinking and moving the eyes
- undisturbed sleep patterns
People with locked-in syndrome often gain alertness gradually, however they will not regain movement, sensation or speech. They require round the clock care and assistance and rely on medical equipment to help them breathe and feed.
Making a diagnosis
A range of tests may be carried out to diagnose locked-in syndrome, including:
- Brain imaging scans, including an MRI scan and magnetic resonance angiography: these images may highlight damage to the pons and identify blood clots
- An EEG (electroencephalogram), which is used to measure electrical activity. this may provide information about sleep patterns and brain activity
- Electromyography and nerve conduction tests, which analyse the muscles at work and rest. They help to determine if there is any damage to the muscles and nerves
Treatment for locked-in syndrome
Treatment pathways depend on the underlying cause, which is treated as a priority and may involve medication or surgery.
People with locked-in syndrome are often unable to breathe independently and they cannot feed through the mouth normally. A feeding tube is inserted through the stomach (this is known as gastrostomy).
As communication is only possible through the eyes, it is important to establish a kind of code as quickly as possible and encourage communication with the health team and family members.
Rehabilitation is very important and is designed to support the individual and build on any small improvements that become apparent. In cases where major improvements are made, physiotherapy and occupational therapy become very important in encouraging development and motor skills and promoting independence.