gamma-knife therapy in acoustic neuroma

During 1992-95 79 patients suffering from acoustic neuromas were treated by radiosurgery at the Department of Neurosurgery of the University Medical S chool at Graz. Fifty-one patients underwent gamma-knife treatment as primar y therapy, 28 patients after neurosurgical operation because of remaining o r recurrent tumour. The tumour diameter ranged from 5.3 to 37.7 mm and pati ent follow-up was 3-6 years. In all patients contrast-enhanced CT (until 19 93) or MRI was performed, with the stereotactic head-frame applied to deter mine the target. The total central tumour dose varied from 14 to 50 Gy, the total peripheral dose ranged from 9 to 18 Gy, respective to the 30-70% iso dose. Tumour shrinkage was seen in 10.1% of the neuromas and 57.0% showed v ariable changes in morphology, due to a partial necrosis. There was no incr ease in tumour size during the study. The overall hearing preservation rate was approximately 85%. Seven patients became deaf after radiosurgery, six patients (7.6%) developed facial neuropathies after stereotactic treatment and two patients (2.5%) trigeminal symptoms. Three patients developed a pos t-therapeutic perifocal oedema, two of them asymptomatic, the other one wit h neurological signs, including vertigo, nausea and dizziness. All patients returned to their preoperative function level within a couple of days. Ste reotactic radiosurgery using the Leksell gamma-knife is a safe, non-invasiv e therapy for acoustic neuromas and is a good alternative to microsurgery i n cases of inoperable patients and those who refused surgery. For recurrent or partially removed tumours, radiosurgery seems to be the therapy of choi ce.