Long-term outcomes after Gamma Knife surgery for vestibular schwannomas: a 10-year experience.

OBJECT

The authors sought to assess the results of Gamma Knife surgery (GKS) in patients with vestibular schwannomas (VSs).

METHODS

Seventy-four consecutive patients (33 men and 41 women) were evaluated by means of serial imaging studies, clinical examinations, and questionnaires. Nineteen patients had undergone resection of their VS. Facial nerve function was normal in 63 patients (85.1%) before GKS, and 63.5% of them had useful hearing. The prescription peripheral dose varied between 10 and 14 Gy (mean 12.27 +/- 0.96 Gy); the corresponding central dose was 21 to 30 Gy (mean 24.9 +/- 2.18 Gy). The mean volume of the tumor at GKS was 10.79 +/- 5.52 ml (range 0.11-27.8 ml). A mean of eight isocenters (range 3-17) was used for treating these lesions. At a median follow-up period of 68.3 months (range 30-122 months), tumor shrinkage was observed in 60 patients (81.1%), and the tumor size was stable in 11 (14.8%). Persistent neuroimaging demonstrated evidence of progression in only three patients (4.1%): two underwent repeated GKS after an interval of 18 months and one continues to be observed. Five patients experienced trigeminal dysfunction: in three the dysfunction was transient and in the other two the dysfunction persists. Three patients suffered facial palsy. Useful hearing was preserved in 34 patients. Thirteen patients experienced some degree of hearing improvement. Deterioration of hearing was found in 13 of 62 patients who had Class I or II hearing before treatment.

CONCLUSIONS

Gamma Knife surgery prevents tumor growth; it achieves excellent neurological function preservation and produces few treatment-related complications.