[Operative results in 45 cases of acoustic neurinoma: technical comments on the preservation of the facial nerve and hearing function].

This report deals with the operative results in 45 cases of acoustic neurinoma treated in our service during the past six years. Surgery was performed in a lateral position through a small suboccipital craniectomy. Radical total removal of the tumor was achieved in 37 cases and nearly total resection was performed in 8 cases to preserve the facial nerve. Major complications occurred in 2 patients; one died of acute respiratory distress and the other had persisting ataxia due to damage of AICA. The facial nerve was anatomically preserved in 38 cases. Six patients in whom the facial nerve was not preserved underwent various types of facial nerve reconstruction. Postoperative follow-up showed excellent facial nerve function in 32 cases, good function in 11 and poor function in 3. Hearing was preserved in only one case of 11 cases who had preoperatively retained auditory function. Followings are important points for the preservation of postoperative facial nerve function and useful hearing. FACIAL NERVE: Intraoperative identification of facial nerve is crucial. The facial nerve was in most cases compressed ventrally by the tumor, however, 4 cases showed abnormal course of the facial nerve (dorsal in 1, rostral in 1 and caudal in 2 cases). The facial nerve was extremely thin and adherent at the ventral side of the tumor and invisible under the microscope in 60% of the cases. When the facial nerve is hardly separated from the tumor capsule, nearly total resection (leaving thin tumor capsule with the membranous facial nerve) is recommended.(ABSTRACT TRUNCATED AT 250 WORDS)