RESUMEN
OBJECTIVES: To determine predictive factors influencing postoperative facial palsy during retro sigmoid approach in vestibular schwannoma surgery. MATERIAL AND METHODS: Retrospective study over 230 patients with vestibular schwannoma, mostly stade I and II, operated by retro sigmoid approach, by the same oto neuro chirurgical team between 1993 and 2004. Pre and post operative parameters taken into consideration: quantitative: age and sex, audiometric parameters, duration of clinical symptoms; qualitative: tumor anatomic factors and facial nerve function according to House Brackmann classification. RESULTS: 8 days after surgery, 92% of patients have a normal or subnormal facial nerve function, 5% a facial paresis and 3% a paralysis. After one year, only 4% of patients still have a grade III to VI paralysis. Latency of vertigo with facial nerve paralysis is 4.33 vs. 1.97 year in absence of paralysis. Hearing conservation is 85% without facial nerve paralysis vs. 58% with facial nerve paralysis; Wave III latency (PEAP) with facial nerve paralysis is 4.54 vs. 4.28 ms if not. CONCLUSION: Significant predictive factors of facial nerve palsy outcome are: age, post surgery hearing conservation, wave III latency, difficulty in tumor dissection, vertigo latency.