Predictive Factors of Unfavorable Events After Gamma Knife Radiosurgery for Vestibular Schwannoma

Objective Gamma Knife radiosurgery (GKS) for the treatment of vestibular schwannoma (VS) introduces risks to the facial nerve and auditory perception and may involve post-treatment complications such as pseudoprogression, hydrocephalus, and other cranial neuropathies. This study of patients with VS who underwent GKS investigated radiosurgical results, focusing on post-treatment complications and identifying the factors that predict such complications. Methods We undertook a retrospective review of all VS patients treated with the Perfexion Leksell Gamma Knife between November 2007 and October 2010 at our institution. Patients who underwent at least 12 months of clinical and radiologic assessments before and after GKS were included. Results All 235 patients were included in the analyses reported here. The 5-year serviceable hearing and facial nerve preservation values were 73.9% and 94.3%, respectively. Following GKS, 43 patients (18.30%) showed pseudoprogression, 15 (6.38%) exhibited hydrocephalus, 22 (9.36%) showed trigeminal neuropathy, 14 (5.96%) showed vertigo, and 25 (10.64%) showed facial myokymia. According to multivariate analysis, solid tumor nature was significantly associated with pseudoprogression and patient age was significantly associated with hydrocephalus. Patients receiving margin doses ≥13 Gy had a significantly higher probability of loss of serviceable hearing. Patients with smaller tumors had a trigeminal nerve preservation rate comparable with patients harboring larger tumors. Patients receiving margin doses <13 Gy or older patients had a significantly higher probability of vestibular nerve dysfunction. Conclusions Further prospective studies should be designed to provide further insight into the exact relationship between the predictive factors we investigated and post-treatment complications.