DELAYED-ONSET FACIAL-NERVE DYSFUNCTION FOLLOWING ACOUSTIC NEUROMA SURGERY

Delayed onset facial nerve dysfunction following acoustic neuroma surg ery is an under-appreciated phenomenon. The authors have recently revi ewed long-term (>1 year) facial nerve outcome in 129 patients who unde rwent acoustic neuroma removal with the aid of cranial nerve monitorin g between 1986 and 1990. The facial nerve was anatomically preserved i n 99.2% of the patients, and at one year, 90% of all the patients had House-Brackman in (H-B) grade I or II facial nerve function. Delayed o nset worsening of facial nerve function was noted in 38 of 129 (29%) p atients, most of which occurred in the first few postoperative days. T he incidence increases to 41% (38 of 93) when corrected for those with immediate H-B grade VI weakness, and who therefore could not manifest further deterioration. The facial nerve function either deteriorated from normal to abnormal or increased in severity of weakness. Delayed facial palsy was not related to the size of tumor or the surgical appr oach. The most common occurrence was that of a patient with H-B grade I or II facial nerve function worsening to H-B grade VI in the postope rative period. The prognosis for recovery of facial nerve function fol lowing delayed palsy was excellent. In the majority of cases, the reco very was complete within the first 6 months without specific treatment . Comparable to the patients without delayed palsies, 89% (34 of 38) o f the cases had H-B grade I or II and 97% (37 of 38) had H-B grade III or better facial nerve function at 1 year. This review suggests a sur prisingly high incidence of delayed facial palsy following acoustic ne uroma surgery, which fortunately has an excellent prognosis for sponta neous recovery.