Surgical results in 254 cases of acoustic tumors operated on by the same neurosurgeon (T.S.) were reported. Based on the tumor size in the CP-angle cistern, cases were divided into 4 groups: Group S: AT<1 cm, Group M: 1 cm≦AT<2 cm, Group L: 2 cm≦AT<4 cm, Group G: 4 cm≦AT. The number of cases for each group was 11, 60, 139 and 44, respectively. Results: The tumors were totally or subtotally removed in all cases in both Group S and Group M. However, in 3% of the cases in Group L and 11% of the cases in Group G the tumors were partially removed for the preservation of hearing. Anatomical preservation of the facial nerve was achieved in 96.8% (243/251) of the patients. As to the facial nerve function, the rate of House-Brackmann Grade 1 & 2 in Group S was 91% at discharge, 91% at 6 months after the operation and 100% at 1 year after the operation. It was 83%, 96% and 96% in Group M, 61%, 81% and 91% in Group L, 63%, 74% and 78% in Group G, respectively. Thus, the facial nerve function improved with time in cases where the facial nerve were anatomically preserved. Useful hearing was preserved in 90.0% (9/10) of the patients in Group S, 59.0% (23/39) of Group M, and 39.6% (21/53) of Group L. Even in Group G, useful hearing was preserved in 2 out of 3 pts. Over all, the rate of useful hearing preservation was 52.4% (55/105). Conclusion: Both facial nerve function and useful hearing can be preserved well in tumors smaller than 2 cm in diameter.
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