HEARING PRESERVATION IN ACOUSTIC NEURINOM A SURGERY - INTEREST OF COMBINED RETROSIGMOID AND MIDDLE FOSSA APPROACHES

We report our experience of hearing preservation in acoustic neurinoma surgery, using combined retrosigmoid and middle fossa approaches. Fif ty neurinomas operated on between 1987 and 1994 were included in this retrospective study. Hearing preservation surgery was performed for pa tients with grade II or grade III tumors (mean average tumor diameter: 14.4 mm), presenting with normal or serviceable pre-operative hearing (pure tonal average decrease less than 50dB speech discrimination sco re better than 50%). Isolated middle fossa approach was used in 3 case s, isolated retrosigmoid approach in 2 cases. The 45 other cases were operated on using both routes during the same procedure. Total removal of the tumor with anatomic facial preservation was performed in all c ases, No death occurred. The facial function assessed 3 months after s urgery was good in 84% of cases (House-Brackmann grades I or II). The mean follow-up was 42 months. Postoperative hearing was measurable in 48% of cases and serviceable in 30% of cases. The size of the tumor an d the level of preoperative hearing appear to be the most important pr edictive criteria for successful hearing preservation.