Regeneration of facial nerve after hypoglossal facial anastomosis: an animal study.

Hypoglossal-facial nerve anastomosis was carried out in 20 adult guinea pigs. Electromyographic responses of orbicularis oculi muscle evoked by blink reflex were recorded 2, 4, and 6 months after surgery. Then the anastomotic site was reopened, and a segment of buccal branch and the anastomotic trunk were resected for detailed histologic study. Regenerated axons were counted and the cross-sectional area of axons and fasciculi was measured. Data obtained from both blink reflex measurement and histologic study demonstrate a good quality of regeneration of the facial nerve from the hypoglossal nerve completed 6 months after the operation. In addition a new nerve bundle was regenerated from the proximal stump of the facial nerve connecting to the anastomotic site in 80% of the animals. Postoperative change in innervation pattern of the facial nerve was also illustrated.