[Gamma knife for elderly patients with large vestibular schwannomas: 11-year follow-up]

To evaluate the effect of Leksell Gamma Knife (LGK) on elderly patients with large vestibular schwannomas (VS) and to summarize the indications for LGK in patients with large VS.

From July 1994 to July 2000, 50 elderly patients (age range: 60.0 - 81.0 years) with large VS were treated by LGK as primary treatment modality. The maximal tumor diameter ranged from 31.0 to 61.0 mm [mean, (36.0 +/- 6.1) mm] and mean tumor volume was (14.8 +/- 8.0) cm(3) (range, 7.5 - 54.0 cm(3)). The maximal dose irradiated to tumor ranged from 22.0 to 28.0 Gy [mean: (25.0 +/- 1.6) Gy] and the mean tumor marginal dose was (12.3 +/- 0.9) Gy (range, 9.5 - 14.0 Gy). The mean follow-up duration was (86 +/- 12) months (range: 68 - 138 months).

Of the 50 patients with follow-up data, 4 were deceased and 46 survived. Two patients with giant VS died at 6 and 9 months post-LGK respectively because of tumor swelling. Another two patients died of stroke or heart attack at 3 years and 4 years after LGK respectively, but their tumors decreased in volume. Clinical response: hearing: 14 (28%) patients preserved useful hearing as pre-LGK; 32 patients had unchanged or deteriorated hearing. Facial palsy: two patients developed mild facial palsy at 4 and 8 months respectively, one of them recovered and another improved later. Seven patients developed hydrocephalus around 6 months post-LGK and had V-P shunt. Eighteen patients had deteriorated facial numbness because of tumor swelling, 15 of them improved 3 years later. Tumor response: in 46 surviving patients, 43 tumors decreased markedly in size, 2 tumors remained stable in volume, 1 tumor progressed at five years and had second LGK. In this series tumor control rate was 94% (47/50).

LGK provides an effective treatment for some selected large VS (maximal diameter