Locked-In Syndrome – EEG Alpha Must Exclude — SCE Neurology MCQ

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HardCerebrovascular DiseaseLocked-In Syndrome – EEG Alpha Must ExcludeSCE Neurology

A 70-year-old man with a posterior circulation stroke has bilateral ptosis, bilateral facial weakness, quadriplegia, and is unresponsive. However, EEG shows normal reactive alpha rhythm. What condition must be excluded before declaring this patient as having impaired consciousness?

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Correct answer: C — Locked-in syndrome — the patient may be fully conscious but unable to move or communicate except through vertical eye movements

A reactive alpha rhythm on EEG indicates cortical awareness — this is incompatible with coma, vegetative state, or brain death. In a patient with quadriplegia and bilateral facial weakness from a ventral pontine lesion, locked-in syndrome must be considered. The patient may be fully conscious but unable to demonstrate this through movement (except vertical eye movements and blinking, which bypass the damaged ventral pons). Testing for vertical eye tracking is critical before making any diagnosis of impaired consciousness. A: Brain death has no EEG activity. C: Catatonia has different EEG. D: Psychogenic unresponsiveness has reactive EEG but different clinical context. E: Depression has different features.

Reference: Academy of Medical Royal Colleges Disorders of Consciousness Guidelines; Plum & Posner