Histological and ultrastructural changes in idiopathic facial palsy.

Light- and electron-microscopic findings in the facial nerve are reported in a patient who died 8 months after the onset of acute idiopathic facial palsy. There were signs of regeneration after axonal destruction, and inflammatory infiltrates confined to the intracanalicular part of the nerve were found. These findings suggest a viral or immunological etiology, which may become pathogenetic due to the length and narrowness of the Fallopian canal.