Summary:Patients with satisfactory facial nerve function [House—Brackmann (HB) grade I or II] immediately after acoustic neuroma surgery are at risk for delayed facial paralysis. To study this problem, 255 consecutive patients who underwent acoustic neuroma excision with facial nerve preservation were identified. Delayed facial paralysis occurred in 62 (24.3%) patients; 90% ultimately recovered to their initial postoperative HB grade, and 98.3% recovered to within one grade of their initial HB level. Paralysis occurred at an average of 3.65 postoperative days (range, 1-16 days). The average time to maximal recovery for those with changes of 1,2,3, and 4 HB grades was 5.6,21.5,39.8, and 50.5 weeks, respectively. The early onset of paralysis (<48 h after surgery) resulted in shorter average recovery times. Of patients who demonstrated nerve deterioration to grades IV-VI, 20 of 38 required tarsorrhaphy or gold-weight placement. We conclude that the overwhelming majority of patients with delayed facial paralysis after acoustic neuroma surgery do eventually recover to their postoperative HB grade. The magnitude and timecourse of delayed facial paralysis are predictive factors for subsequent recovery.