• Yukyeng Byeon, Chaejin Lee, Gung Ju Kim, Juhee Jeon, Sangjoon Chong, Sang Woo Song, Young Hyun Cho, Seok Ho Hong, Chang-Ki Hong, Jeong Hoon Kim, and Young-Hoon Kim.
• 1Department of Neurosurgery, Asan Medical Center, University of Ulsan, College of Medicine, Songpa-gu, Seoul; and.
• J. Neurosurg. 2024 Sep 13: 1101-10.

ObjectiveGamma Knife radiosurgery (GKRS) is widely used for treating small- to medium-sized or postoperative residual, recurrent lower cranial nerve schwannomas (LCNSs). This study aimed to evaluate the radiographic and neurological outcomes of GKRS for LCNS.MethodsA total of 60 patients with 47 jugular foramen schwannomas (JFSs) and 13 hypoglossal nerve schwannomas (HNSs) who underwent GKRS were included. Dysphagia (40.4%) and hoarseness (23.4%) were the most common preexisting symptoms associated with JFS, whereas tongue deviation (53.8%) was prevalent in HNS. The median tumor volumes were 3.2 cm3 and 2.2 cm3 for JFSs and HNSs, respectively. The median marginal dose administered to the tumor was 13 Gy (range 12-15 Gy). The median follow-up duration was 52.8 months.ResultsLocal tumor control was achieved in 91.5% of JFSs and 92.3% of HNSs. The preexisting neurological symptoms improved in 48.9% of patients with JFS and remained stable in 29.8%. However, 10 patients (21.3%) experienced exacerbation of symptoms associated with cranial nerves VII, VIII, IX, X, and XI. Among these, 3 patients (6.4%) exhibited persistent symptomatic deterioration. Patients with HNSs demonstrated a stable trajectory without symptom aggravation. Larger tumor volume and cystic portion were significantly associated with tumor progression (p = 0.017 and 0.003, respectively), and post-GKRS transient swelling was associated with neurological deterioration (p = 0.044).ConclusionsGKRS is an alternative treatment option for LCNS that reduces surgical morbidity and enhances tumor control. However, GKRS can potentially lead to neurological deterioration, necessitating extreme caution throughout the procedure, specifically for JFSs.

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