[The sub-occipital approach in functional surgery of acoustic neuroma].

In this study the Authors analyze 380 acoustic neuroma removals carried out from 1972 to 1992 focusing their attention on 90 attempts to save hearing by employing a suboccipital approach. In this series the facial nerve was preserved in 99% of the cases with completely normal function in 78%. The cochlear nerve was anatomically preserved in 96% of the subjects. According to the Shelton-Brackmann classification applied to evaluate hearing results, good hearing (Class A = PTA < or = 30 dB; SDS > or = 70%) was obtained in 12% of the cases, serviceable hearing (Class B = PTA < or = 50 dB; SDS > or = 50%) in 13%, measurable hearing (Class C = any measurable hearing) in 19% and anacusis (Class D) in 56% of the patients. CSF leak occurred in 6.6% of the cases, meningitis in 2.2%, paresis or paralysis of the ninth and tenth cranial nerves in 3% and ataxia in 2%. In acoustic neuroma surgery, hearing preservation is a new but complicated topic. In fact, some operative steps--such as the separation of tumor from nerves and arteries, tumor mass reduction, exposure of the end of the IAC--certainly influence surgical results, but are a matter of uncontrollable variance even within series from the same surgeon and render hearing preservation an innovative idea still awaiting, however, a controllable procedure. The ethical feasibility of hearing preservation is confirmed by our results in which hearing preservation attempts using a suboccipital approach have the same morbidity that the translabyrinthine route would have in the same patient.