Neuropathy of the facial nerve in chronic otitis media without associated facial paralysis. A human temporal bone study.

In the present study we examined whether pathologic changes can exist in the facial nerve in chronic otitis media (COM) when facial nerve function is clinically normal. In so doing, 20 human temporal bones were examined. Each case had a premortem history of COM without facial paralysis. Nine normal temporal bones were also studied. Signs of degenerative neuropathy involving the facial nerve were found in 2 out of the 20 cases studied. In the first of these 2 cases the tympanic segment of the facial nerve showed focal areas of demyelinization, as well as hypertrophy and proliferation of the Schwann cells but without loss of the axons. These areas were also occasionally associated with increased numbers of mast cells. In the second case the most striking finding was the presence of small dark globules in the mastoid segment of the facial nerve. These formations were assumed to be products of cellular and myelin degeneration. Our studies suggest that COM may be associated with degenerative changes in the facial nerve without clinical impairment of its function. Nonetheless these changes may have the potential for the development of facial paralysis during COM.