SEVERE CRANIAL NERVE INVOLVEMENT IN LONGSTANDING DEMYELINATING POLYNEUROPATHY - A CLINICOPATHOLOGICAL CORRELATION

Onion bulb formations involving cranial nerves are an unusual patholog ic feature. We report the postmortem neuropathologic findings in a 69- year-old man with a longstanding neuropathy characterized by progressi ve muscle weakness, sensory ataxia and multiple cranial nerve abnormal ities. Electrodiagnostic testing disclosed features of an acquired dem yelinating polyneuropathy. Treatment with corticosteroids and plasmaph eresis resulted in no change in his neurologic status, and the patient died after repeated episodes of pneumonia and sepsis. Autopsy showed widespread onion bulb formation in cranial nerves III, IV, V, VI, X, X I and XII, anterior and posterior spinal nerve roots, dorsal root gang lia and multiple peripheral nerves, some of which also had foci of epi neurial perivascular inflammation. Muscle sections revealed severe neu rogenic atrophy. This case demonstrates that, in longstanding acquired demyelinating neuropathy, the cranial nerves also undergo repetitive cycles of demyelination and remyelination resulting in severe weakness of the bulbar musculature and histologic features of hypertrophic neu ropathy.