Functional and histological evaluation of the facial nerve in patients who have undergone hypoglossal-facial nerve anastomosis after removal of cerebellopontine angle tumors

Facial nerve specimens removed from ten patients who underwent hypoglossal-facial nerve anastomosis for facial palsy following removal of cerebellopontine angle tumors were studied histologically. Facial nerve function prior to the anastomosis surgery and the degree of postoperative functional recovery were compared with the histological results. The recovery of facial palsy after the anastomosis surgery was excellent or satisfactory in nine patients and the endoneurium within the nerve fascicles was well-preserved. The recovery of facial palsy was poor in one patient who had severe fibrosis of the endoneurium. The histological and ultrastructural features of the facial nerve were closely related to the occurrence of facial palsy prior to tumor removal, the status of the nerve after tumor removal, and the interval between tumor removal and anastomosis surgery. Based on these histological and functional relationships, the timing and indications for anastomosis surgery are discussed.