Conservative management, gamma-knife radiosurgery, and microsurgery for acoustic neurinomas: a systematic review of outcome and risk of three therapeutic options.

Conservative management, gamma-knife (GK) radiosurgery, and microsurgery are therapeutic options for acoustic neurinomas (ANs). To determine the outcomes and risks of these methods this systematic review analyzed data from 903 patients with conservative management, 1475 with GK radiosurgery, and 5005 with microsurgery from 38 studies identified in MEDLINE searches. Conservative management over a 3.1-year period showed that 51% of ANs showed a tumor growth, an average tumor growth rate was 1.87 mm year-1, 20% of ANs ultimately required surgical intervention, and a third of the patients lost useful hearing. GK radiosurgery significantly reduced the percentage of ANs that enlarged, to 8%, and reduced the percentage that underwent microsurgery to 4.6% over a 3.8-year period. Microsurgery removed 96% of ANs totally, with tumor recurrence, mortality, and major disability rates of 1.8%, 0.63%, and 2.9%, respectively. The majority of ANs grow slowly, but ultimately require intervention. Carrying the risk of hearing loss, conservative management should be supplemented with close follow-up. With a low rate of morbidity, GK radiosurgery suppresses tumor growth and provides good tumor control. Microsurgery provides the best tumor control, although mortality and morbidity are not completely eliminated.