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 or pseudobulbar 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.
Ventral pontine damage/injury
- Bilateral ventral pontine stroke (most common)
- Direct trauma to the ventral pons
- Pontine demyelination (e.g., multiple sclerosis affecting the ventral pons, )
- ventral pons or affecting the
- (postinfectious or postimmunization)
To remember that locked-in syndrome is caused by the damage to the ventral (i.e., basilar) part of the pons, think of someone locked in the basement.
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
- Paralysis of all 4 limbs and torso (quadriplegia)
- Horizontal gaze palsy: caused by damage to the center for horizontal gaze and the VIthcranial nerve nucleus, which both lie in the pons
- Respiratory abnormalities
- Preservation of the following functions
Patients with LIS can only communicate by blinking and vertical eye movements!
Patients with locked-in syndrome due to basilar artery occlusion are blocked like a basalt rock!
- CT/MRI of the brain: : indicated in all patients to identify the underlying cause
- Lumbar puncture: indicated if an infectious etiology or is suspected
- Neuropsychological testing
The differential diagnoses listed here are not exhaustive.
In acute phase
- Supportive therapy (airway, breathing, circulation)
- Treat the underlying, often life-threatening, disorder (see “Etiology” for causes)
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 change 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
- 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