Locked-in syndrome results from infarction of which brain region?

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Locked-in syndrome occurs when there is bilateral damage to the ventral brainstem, most often the ventral portion of the pons (basilar pontine region), and it can extend to the ventral medulla. This area contains the corticospinal and corticobulbar tracts; when these pathways are destroyed on both sides, voluntary movement of the limbs, face, and speaking muscles is lost, but consciousness remains because the dorsal tegmentum and reticular activating system are spared. Eye movements, especially vertical movements, are often preserved, allowing communication by gaze and giving the distinctive presentation. Infarction of the cerebellum would produce ataxia rather than complete paralysis with preserved consciousness, lesions of the midbrain produce different oculomotor or behavioral syndromes, and frontal lobe damage affects cognition and personality more than producing locked-in motor paralysis.