Critical assessment of operative approaches for hearing preservation in small acoustic neuroma surgery: retrosigmoid vs middle fossa approach

For hearing preservation in acoustic neuroma (AN) surgery, the middle fossa (MF) or retrosigmoid (RS) approach can be used. Recent literature advocates the use of the MF approach, especially for small ANs. To present our critical analysis of operative results comparing these 2 approaches. We reviewed 504 consecutive AN resections performed between November 1998 and September 2007 and identified 43 MF and 82 RS approaches for tumors smaller than 1.5 cm during hearing preservation surgery. Individual cases were examined postoperatively with respect to hearing ability, facial nerve activity, operative time, blood loss, and symptoms resulting from retraction of the cerebellar or temporal lobes. Good hearing function (American Academy of Otolaryngology-Head and Neck Surgery class B or better) was preserved in 76.7% of patients undergoing surgery via the MF approach and in 73.2% of the RS group (P = .9024). Temporary facial nerve weakness was more frequent in the MF group (P = .0249). However, late (8-12 months) follow-up examinations showed good recovery in both groups. The mean operative time was 7.45 hours for the MF group and 5.2 hours for the RS group (P = .0318). The mean blood loss was 280.5 mL for the MF group and 80.8 mL for the RS group (P < .0001). Temporary symptoms of temporal lobe edema (drowsiness or speech disturbance) were noted in 6 MF cases. No cerebellar dysfunction was noted in the RS group. Although hearing and facial nerve function assessed at approximately 1 year was similar with these 2 approaches, the RS approach provided several advantages over the MF approach for ANs smaller than 1.5 cm.