Gamma Knife Radiosurgery for Endolymphatic Sac Tumors: A Single-Institution Experience

Abstract: Background: Endolymphatic sac tumors (ELSTs) are rare, locally aggressive tumors often associated with von Hippel–Lindau disease. Due to their location and hypervascularity, complete surgical excision is challenging, and recurrence is common. Gamma knife radiosurgery (GKRS) has emerged as a potential noninvasive treatment modality, particularly in recurrent or inoperable cases. Methods: A retrospective analysis of five patients with radiologically diagnosed ELSTs treated with GKRS at our institution between 2012 and 2023 was performed. Patients who had received either upfront or adjuvant GKRS with a minimum of 1 year follow-up were included. Treatment planning involved frame-based MRI and GKRS delivery using the Leksell GammaPlan system. Clinical and radiological outcomes were assessed through clinical review and follow-up imaging. Results: Of the five patients, two received primary GKRS, and three received secondary GKRS following surgical resection. Marginal doses ranged from 20 to 25 Gy. At follow-up, MRIs showed stable disease with no increase in tumor size. Clinically, patients remained stable, with no worsening or emergence of new neurological symptoms. No procedure-related or radiation-induced complications, including radiation necrosis, were observed, and none required corticosteroid therapy. Conclusions: GKRS is a safe and effective treatment modality for the management of ELSTs, particularly in residual or recurrent disease. Our experience suggests that GKRS offers excellent radiological control and symptom stabilization, supporting its role as both a primary and adjunctive treatment option.