LONG-TERM OUTCOMES AFTER RADIOSURGERY FOR ACOUSTIC NEUROMAS

Background Stereotactic radiosurgery is the principal alternative to m icrosurgical resection for acoustic neuromas (vestibular schwannomas). The goals of radiosurgery are the long-term prevention of tumor growt h, maintenance of neurologic function, and prevention of new neurologi c deficits. Although acceptable short-term outcomes have been reported , long-term outcomes have not been well documented. Methods We evaluat ed 162 consecutive patients who underwent radiosurgery for acoustic ne uromas between 1987 and 1992 by means of serial imaging tests, clinica l evaluations, and a survey between 5 and 10 years after the procedure . The average dose of radiation to the tumor margin was 16 Gy, and the mean transverse diameter of the tumor was 22 mm (range, 8 to 39). Res ection had been performed previously in 42 patients (26 percent); in 1 3 patients the tumor represented a recurrence of disease after a previ ous total resection. Facial function was normal in 76 percent of the p atients before radiosurgery, and 20 percent had useful hearing. Result s The rate of tumor control (with no resection required) was 98 percen t. One hundred tumors (62 percent) became smaller, 53 (33 percent) rem ained unchanged in size, and 9 (6 percent) became slightly larger. Res ection was performed in four patients (2 percent) within four years af ter radiosurgery. Normal facial function was preserved in 79 percent o f the patients after five years (House-Brackmann grade 1), and normal trigeminal function was preserved in 73 percent. Fifty-one percent of the patients had no change in hearing ability, No new neurologic defic its appeared more than 28 months after radiosurgery. An outcomes quest ionnaire was returned by 115 patients (77 percent of the 149 patients still living). Fifty-four of these patients (47 percent) were employed at the time of radiosurgery, and 37 (69 percent) remained so. Radiosu rgery was believed to have been successful by all 30 patients who had undergone surgery previously and by 81 (95 percent) of the 85 who had not. Thirty-six of the 115 patients (31 percent) described at least on e complication, which resolved in 56 percent of those cases. Conclusio ns Radiosurgery can provide long-term control of acoustic neuromas whi le preserving neurologic function. (N Engl J Med 1998;339:1426-33.) (C ) 1998, Massachusetts Medical Society.