• Clinical science

Locked-in syndrome

Abstract

Locked-in syndrome (LIS) is a rare condition caused by bilateral damage to the ventral pons, most often due to a stroke. LIS is characterized by quadriplegia and bulbar palsy, caused by the interruption of the corticospinal and corticobulbar tracts in the pons. The only remaining voluntary muscle movements include vertical eye movement and blinking. Consciousness, awareness, cognition, and sensation are preserved. Diagnosis of pontine damage is made on a CT or MRI of the brain. Preserved cognition is diagnosed via EEG and neuropsychological testing. Management in most patients includes tracheostomy, mechanical ventilation, placement of a feeding tube, and physiotherapy. Patients learn to communicate through blinking and/or eye movements and the help of computer programs/speech synthesizers. Some patients may recover a certain degree of motor control, speech, and swallowing ability.

Etiology

References:[1][2][3][4][5]

Clinical features

Locked-in syndrome is typically preceded by a loss of consciousness and subsequent coma lasting for days or weeks. The following symptoms are detected on regaining consciousness:

  • Paralysis of voluntary muscles
  • Preservation of the following functions
    • Normal consciousness, language comprehension, cognition, and ability to make decisions
    • Vertical eye movements; and voluntary blinking
    • Cutaneous sensation
    • Involuntary motor phenomenon: yawning, crying, laughing, and ocular bobbing even though voluntary facial expressions are lost

Patients with LIS can only communicate by blinking and vertical eye movements!

References:[6][7][8][9][10]

Diagnostics

  • CT/MRI of the brain: indicated in all patients to identify the underlying cause
  • EEG
    • Indicated in all patients to rule out brain death
    • Used to measure visual/auditory evoked potentials → nearly normal EEG in LIS
  • Lumbar puncture: indicated if an infectious etiology or Guillain-Barré syndrome is suspected
  • Neuropsychological testing
    • Performed once the patient is stable to assess cognition
    • Patients communicate with eye movements or blinking in response to the test questions → normal or near-normal cognition

Demonstration of preserved cognition, vertical eye movements, and blinking in a quadriplegic, anarthric patient is diagnostic of LIS!

References:[5][6][11][12][13][14]

Differential diagnoses

References:[15][6][16]

The differential diagnoses listed here are not exhaustive.

Treatment

  • In acute phase
    • Supportive therapy (airway, breathing, circulation)
    • Treat the underlying, often life-threatening, disorder (see “Etiology” for causes)
  • In the rehabilitative phase

References:[16][17][18]

Prognosis

  • Patients with LIS may show
    • Complete recovery (transient LIS): e.g., in patients with Guillain-Barré syndrome
    • Moderate recovery: recovery of some motor function, ability to breathe and/or swallow, independence in some activities of daily living
    • Minimal to no recovery
  • Quality of life: Patients with LIS may suffer from depression and apathy but most report a meaningful quality of life.

References:[8][17]

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last updated 10/26/2018
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