Eye movement and vestibular dysfunction in mitochondrial A3243G mutation.

Studying eye movements and vestibular function would provide insights into brain networks that are vulnerable in mitochondrial disorders. We sought eye movement and vestibular abnormalities in three Korean patients with a mitochondrial A3243G point mutation. The patients suffered from vertigo and imbalance during the stroke-like and seizure episodes from lesions involving the posterior cerebral cortex, which were accompanied by bilateral saccadic hypermetria and horizontal gaze-evoked nystagmus. Furthermore, two patients showed bilateral impairments of the vestibulo-ocular reflex during head impulses for the horizontal and posterior canals on both sides in the absence of caloric paresis. Cerebellar atrophy was prominent on MRIs in two patients and was less marked in the other patient. These findings imply that the cerebellum is susceptible to neuronal energy deficiency due to mitochondrial A3243G point mutation.