Mitochondrial encephalomyopathy: a rare genetic cause of sensorineural hearing loss.

A 44-year-old man with a documented 12-year history of progressive sensorineural hearing loss developed a generalized tonic-clonic seizure followed by a visual field deficit and apraxia. Six months later he developed a peripheral neuropathy and muscle fatigue followed by a slowly progressive aphasia and cortical blindness as well as increased seizure activity. A computed tomography scan showed bilateral basal ganglion calcification. The serum lactate level was elevated at 3.4 mEq/dL. A muscle biopsy enabled the diagnosis of mitochondrial myopathy. This disorder is presented as an unusual cause of progressive sensorineural hearing loss in adults.