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Locked-in syndrome (LIS), also known as pseudocoma, is a condition in which a patient is aware but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles in the body except for vertical eye movements and blinking.
- EEG is normal in locked-in syndrome
- Total locked-in syndrome, or completely locked-in state (CLIS)
- Version of locked-in syndrome wherein the eyes are paralyzed as well
- Fred Plum and Jerome Posner coined the term for this disorder in 1966
Aetiology
- Poisoning (krait bite and other neurotoxic venoms, as they cannot, usually, cross the BBB
- Brainstem stroke
- Diseases of the circulatory system
- Medication overdose
- Osmotic demyelination syndrome or, central pontine myelinolysis (secondary to excessively rapid correction of hyponatremia [>1 mEq/L/h])
- Damage to nerve cells, particularly destruction of the myelin sheath
- Stroke or brain hemorrhage (usually of the basilar artery)
- Traumatic brain injury
- Brain-stem lesions
Clinical features
- Results from quadriplegia and the inability to speak in otherwise cognitively intact individuals.
Differential diagnosis:
- Amyotrophic lateral sclerosis
- Bilateral brainstem tumors
- Brain death (of the whole brain or the brain stem or other part)
- Coma (deep and/or irreversible)
- Guillain–Barré syndrome
- Myasthenia gravis
- Poliomyelitis
- Polyneuritis
- Vegetative state (chronic or otherwise)
Management
Neither a standard treatment nor a cure is available
- Neuromuscular electrical stimulation (NMES)
- Regain limited muscle function
Symptomatic management:
- Assistive computer interface technologies:
- Dasher combined with eye tracking (help people with LIS communicate with their environment)