The pathology of facial and vestibular neuronitis

To measure disease of idiopathic nature in the ganglia of the human facial (FN) and vestibular nerves (VN).

One hundred horizontally sectioned human temporal bones (TB) were examined under light microscopy. The TB were sectioned at 20 microm, and every 10th section was stained with hematoxylin and eosin and mounted. The volume fractions (VF) of degenerated cells in the FN ganglion and focal axonal degeneration in the VN were measured with stereologic techniques.

Twenty-five TB were excluded because of artifact or poor staining of the FN and VN. Fifty-one TB contained degenerated cells in the FN meatal ganglion (MG) and/or focal axonal degeneration in the VN. Thirty-one FN had degenerated cells in the MG (VF = 1% to 55%) and none in the geniculate ganglion. In 45 TB, focal axonal degeneration was found in the VN (VF = 1% to 50%; the VF was less than 15% in all but one TB). MG and VN degeneration occurred together in 25 TB. None of the cases had a history of FN paralysis, but 20 had a history of vertigo. Twenty-four TB from patients of similar ages with similar otopathologies did not reveal degeneration in the FN or VN.

The FN and VN lesions in these 51 TB may be virus-induced and reflect a higher incidence of idiopathic FN and VN neuronitis than previously thought.