Faciohypoglossal anastomosis: does the morphology of the facial nerve affect the functional result?

We report the results of a histological study of facial nerve specimens obtained at the time of faciohypoglossal anastomosis. We examined sections from 24 patients using light and electron microscopy in order to determine the extent of the degenerative process with time and its relationship to the functional results of the anastomosis. We graded the histological features associated with degeneration, regeneration, and fibrosis on an ordered nominal scale from 0 to 3 and correlated them with duration of facial palsy and postoperative facial function. There was no histological evidence of increasing collagenosis or fibrosis with duration of facial palsy, and endoneural fibrosis was a very infrequent finding. There was no evidence that the relative numbers of endoneural fibrocytes or the degree of collagenosis had any bearing on the functional result. The presence of large numbers of endoneural tubes, containing nonmyelinated axons, showed a positive correlation with the postoperative facial function, whereas the presence of active axon degeneration showed a negative correlation.