Masseteric-facial anastomosis and hypoglossal-facial anastomosis after lateral skull base and middle ear surgery.

Introduction: Lateral skull base (LSB) and middle ear pathologies often involve the facial nerve (FN), and their treatment may require FN sacrifice. Cases with unidentifiable proximal stump or intact FN with complete FN palsy, necessitate FN anastomosis with another motor nerve in order to restore innervation to the mimicking musculature. The results of hypoglossal-to-facial nerve anastomosis (HFA) and masseteric-facial nerve anastomosis in patients with facial paralysis after middle ear and LSB surgeries, are presented and compared.

Methods: Adult patients with total definitive facial paralysis after middle ear or LSB surgery undergoing facial nerve reanimation through hypoglossal or masseteric transfer anastomosis were enrolled. The facial nerve function was graded according to the House Brackmann grading system (HB). The facial function results at 3 months, 6 months, 12 months, 18 months and at the last follow up (more than 18 months) are compared.

Results: 153 cases of LSB and middle ear surgery presented postoperative facial palsy and underwent facial nerve reanimation surgery with HF in 85 patients (55.5%) and MF in 68 patients (44.5%). The duration of the FN palsy before reconstructive surgery was inversely associated to better FN results, in particular with having a grade III HB (p = 0.003). Both techniques had significantly lower HB scores when an interval between palsy onset and reanimation surgery was 6 months or less (MF p = 0.0401; HF p = 0.0022). Patients who underwent a MF presented significant improvement of the FN function at 3 months from surgery (p = 0.0078). At the last follow-up, 63.6% recovered to a grade III HB and 22.7% to a grade IV. On the other hand, the first significant results obtained in the HF group were at 6 months from surgery (p < 0.0001). 67.8% of patients had a grade III HB after a HF at the last follow-up, 28.8% a grade IV. FN grading at 6 months from surgery was significantly lower in the MF group compared to the HF (p = 0.0351). The two techniques had statistically similar results at later follow-up evaluations.

Discussion/conclution: MF was associated to initial superior results, presenting significant facial recovery at 3 months, and significantly better functional outcomes at 6 months from surgery compared to HF. Although later results were not significantly different in this study, earlier results have an important role in order to limit the duration of risk of corneal exposure.