[A case of mitochondrial myopathy with mononeuritis multiplex]

A case of mitochondrial myopathy with mononeuritis multiplex was described. A 55-year-old man was hospitalized because of blepharoptosis and muscle weakness. His mother also showed blepharoptosis in her elderly stage of life. He had been healthy until 46 years of age, when he first noticed difficulty of speech, followed by bilateral blepharoptosis, weakness of upper limbs, and sensory disturbance in the left occipital, and left upper and lower extremities. These symptoms progressed slowly. On admission, bilateral blepharoptosis was recognized. Slightly to moderate muscle wasting and weakness were observed in the face, neck, trunk, and extremities. Areflexia was observed in the upper extremities. Paresthesia was observed in the left occipital and left hip, and superficial sensation was impaired in the left upper and lower extremities. Electromyographic examination of extremities showed neurogenic changes in the distal muscles and myogenic changes in the proximal muscles. Motor conduction velocities were normal, but sensory conduction velocities decreased in amplitude on the left upper extremity and were not evoked on the left lower extremity. Muscle biopsy specimen revealed numerous "ragged-red" fibers. Cytochrome c oxidase stain showed a decrease in intensity of staining. A sural nerve biopsy showed slight axonal degeneration and slight loss of nerve fibers. Biochemical analysis on biopsy muscle showed partial deficiency of cytochrome c oxidase activity.