Gamma Knife surgery for neurocytoma

Abstract

Although considered benign tumors, neurocytomas have various biological behaviors, histological patterns, and clinical courses. In the last 15 years, fractionated radiotherapy and radiosurgery in addition to microsurgery have been used in their management. In this study, the authors present their experience using Gamma Knife surgery (GKS) in the treatment of these tumors. Between 1989 and 2004, the authors performed GKS in seven patients with a total of nine neurocytomas. Three patients harbored five recurrent tumors after a gross-total resection, three had progression of previous partially resected tumors, and one had undergone a tumor biopsy only. The mean tumor volume at the time of GKS ranged from 1.4 to 19.8 cm3 (mean 6.0 cm3). A mean peripheral dose of 16 Gy was prescribed to the tumor margin with the median isodose configuration of 32.5%. After a mean follow-up period of 60 months, four of the nine tumors treated disappeared and four shrank significantly. Because of secondary hemorrhage, an accurate tumor volume could not be determined in one. Four patients were asymptomatic during the follow-up period, and the condition of the patient who had residual hemiparesis from a previous transcortical resection of the tumor was stable. Additionally, the patient who experienced tumor hemorrhage required a shunt revision, and another patient died of sepsis due to a shunt infection. Based on this limited experience, GKS seems to be an appropriate management alternative. It offers control over the tumor with the benefits of minimal invasiveness and low morbidity rates. Recurrence, however, is not unusual following both microsurgery and GKS. Open-ended follow-up imaging is required to detect early recurrence and determine the need for retreatment.