Hypertrophic neuropathy of the facial nerve.

Hypertrophic neuropathy is a peripheral nerve lesion that is histologically characterized by onion bulb formations around axons. This histologic picture, which is usually seen in generalized hypertrophic neuropathies, can occasionally be observed in single nerves as localized hypertrophic neuropathy. Cranial involvement of such localized hypertrophic neuropathy represents a very rare entity; only a few cases have been reported in the literature. We report the history of a progressive facial paralysis with a tumorous enlargement of the seventh cranial nerve that was clinically suspected of being a schwannoma. Pathological examination permitted the diagnosis of hypertrophic neuropathy.