Locked-in syndrome is a rare neurological disorder in which all voluntary muscles are completely paralysed except those which control the eye movements. Locked-in syndrome is caused by pons injury, a part of the brainstem containing nerve fibres that transmit information to other brain areas. Sometimes named pseudocoma.

CAUSES

The most common cause of the locked-in syndrome is damage to a particular part of the brainstem known as the pons. The pons has important neuronal pathways between the cerebrum, spinal cord, and cerebellum. In locked-in syndrome, there is an obstruction of all motor fibres flowing from a grey matter in the brain through the spinal cord to the muscles of the body, as well as damage to the centres in the brainstem that are essential for facial control and expression. Damage to the pons most commonly occurs from loss of tissue due to lack of blood flow (infarction) or bleeding (haemorrhage) – it can be caused less frequently by trauma.

Many different factors can cause an infarction, such as a blood clot (thrombosis) or a stroke. Additional conditions that can cause locked-in syndrome include infection in certain areas of the brain, tumours, loss of protective insulation (myelin) surrounding nerve cells (myelinolysis), nerve inflammation (polymyositis), and other disorders such as lateral amyotrophic sclerosis (ALS).

SIGNS AND SYMPTOMS

PARALYSIS OF VOLUNTARY MUSCLES

  • Paralysis of all 4 limbs and torso
  • Bulbar palsy

RESPIRATORY ABNORMALITIES

  • Cheyne-Stokes breathing, apnea, loss of voluntary control of breathing
  • Often requires tracheostomy and mechanical ventilation

PRESERVATION OF THE FOLLOWING FUNCTIONS

  • Normal consciousness, language comprehension, cognition, and ability to make decisions 
  • Vertical eye movements and voluntary blinking 
  • Cutaneous sensation 

DIAGNOSIS

  • CT/MRI of the brain
  • EEG 
  • Lumbar puncture
  • Neuropsychological testing

TREATMENT

IN ACUTE PHASE

  • Supportive therapy (airway, breathing, circulation)
  • Treat the underlying, often life-threatening, disorder

IN THE REHABILITATIVE PHASE

  • Respiration: most patients require tracheostomy and mechanical ventilation
  • Feeding: initially feeding tube; possibly gastrostomy
  • Physiotherapy: passive stretching exercises; skeletal muscle relaxants and/or botulinum toxin for spasticity; frequent position changes to avoid pressure sores
  • Speech: eye-gaze sensor-controlled computer communication programs, computer/internet use; use of speech synthesizers; eyelid blinking to communicate yes/no

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