Selection of surgical approaches for small acoustic neurinomas

BACKGROUND The purpose of this study was to evaluate the results of surgery for small acoustic neurinomas at our institute via the middle cranial fossa and retro sigmoid approaches, and to determine the indications for each approach, METHODS Fifty-three patients with unilateral tumors less than 2 cm in diameter were studied. Surgery was performed via the middle cranial fossa approach in 36 tumors and via the retrosigmoid approach in 17 tumors. RESULTS The hearing preservation rate was 68% (36/53) in all patients, 93% (14/15) in patients with intracanalicular tumors, 79% (15/19) in patients with tumo rs less than 1 cm in diameter, and 43% (7/19) in patients with tumors betwe en 1 and 2 cm in diameter. The facial nerve function was excellent or good in 80% (42/53), 74% (11/15), 84% (16/19), and 78% (15/19), respectively. Am ong the 19 patients with tumors between 1 and 2 cm in diameter, the frequen cies of hearing preservation and of excellent or good facial nerve function (47% and 87%, respectively) in the 15 patients approached via the retrosig moid approach were higher than those (0% and 50%, respectively) in the four patients approached via the middle cranial fossa approach. CONCLUSIONS We conclude that tumors smaller than 2 cm should be removed because preserv ation of hearing as well as facial nerve function may be possible in almost all of these patients. Tumors larger than 1 cm should be surgically treate d through the retrosigmoid approach. (C) 2000 by Elsevier Science Inc.