Clinical characteristics of microsurgical removal for vestibular schwannoma after gamma knife radiosurgery

감마나이프 시술 이후에 청신경 종양 제거 수술의 임상적 특징

Background : The aim of the study was to evaluate the clinical characteristics of microsurgery for vestibular schwannoma (VS) after failed gamma knife radiosurgery (GKS) Methods : The retrospective analysis included tumor control rate, pre- and post-operative facial function, postoperative complications, operative findings and difficulties during microsurgery. Results : Between 1991 and 2010, 203cases of VS were surgically treated at the Severance hospital, Seoul, Korea. We had to manage surgically 5 patients that previously underwent gamma knife surgery (GKS) and 3 patients that have previously underwent microsurgery. In patients who underwent GSK, microsurgery was performed via translabyrinthine/ transcochlear approach in all patients. Severe adhesion to the brain stem was identified in 3 patients and the tumor was subtotally removed in 3 patients. Anantomical presevation of the facial nerve was in 5 operations. Dissection of the tumor from the facial nerve was difficult in most interventions because of severe adhesions or color change. The facial nerve function deteriorated in 3 patients, while 2 patients showed no change. Conclusions : Microsurgery for VS after failed GKS is usually considerably more difficult than primary surgery. When making their initial choice of treatment, patients should be counseled that surgery might be more difficult after failed GKS.