Histopathological changes in the temporal bone in Bell's palsy.

The changes in the facial nerve at autopsy are described in a case in which there had been an acute onset of lower motor neurone facial paralysis, with a clinical diagnosis of Bell's palsy, 11 days before death. There was congestion and infiltration of the nerve in the internal auditory meatus and proximal fallopian canal by lymphocytes. Features indicating compression of the nerve in the proximal part of the fallopian canal were seen in the presence of congestion and osteoclastic resorption of the bone surrounding the proximal fallopian canal. Demyelination was present in the tympanic part of the nerve. A bulge below Bill's bar was found on the normal as well as the pathological side and cannot be accepted as evidence of pathological change. It is suggested on the basis of the pathological findings that the symptoms of Bell's palsy may arise from compression of the facial nerve in the proximal part of the fallopian canal.