• Stylianos Pikis, Georgios Mantziaris, Kormath AnandRithikaR1Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia., Ahmed M Nabeel, Darrah Sheehan, Kimball Sheehan, Wael A Reda, Sameh R Tawadros, Khaled Abdelkarim, El-ShehabyAmr M NAMN2Gamma Knife Center Cairo.Departments of4Neurosurgery and., Reem Emad Eldin, Selcuk Peker, Yavuz Samanci, Tehila Kaisman-Elbaz, Herwin Speckter, Wenceslao Hernández, Julio Isidor, Manjul Tripathi, Renu Madan, Brad E Zacharia, Lekhaj C Daggubati, Martínez MorenoNuriaN13Department of Radiosurgery, Rúber International Hospital, Madrid, Spain., Martínez ÁlvarezRobertoR13Department of Radiosurgery, Rúber International Hospital, Madrid, Spain., Anne-Marie Langlois, David Mathieu, Christopher P Deibert, Vivek R Sudhakar, Christopher P Cifarelli, Denisse Arteaga Icaza, Daniel T Cifarelli, Zhishuo Wei, Ajay Niranjan, Gene H Barnett, L Dade Lunsford, Greg N Bowden, and Jason P Sheehan.
• 1Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia.
• J. Neurosurg. 2023 Feb 1; 138 (2): 405412405-412.

ObjectiveThough stereotactic radiosurgery (SRS) is an established safe treatment for small- and medium-sized vestibular schwannomas (VSs), its role in the management of Koos grade IV VS is still unclear. In this retrospective multicenter study, the authors evaluated tumor control and the patient outcomes of primary, single-session SRS treatment for Koos grade IV VS.MethodsThis study included patients treated with primary, single-session SRS for Koos grade IV VS at 10 participating centers. Only those patients presenting with non-life-threatening or incapacitating symptoms and at least 12 months of clinical and neuroimaging follow-up were eligible for inclusion. Relevant data were collected, and the Kaplan-Meier method was used to perform time-dependent analysis for post-SRS tumor control, hearing preservation, and facial nerve function preservation. Univariate and multivariate analyses were performed for outcome measures using Cox regression analysis.ResultsSix hundred twenty-seven patients (344 females, median patient age 54 [IQR 22] years) treated with primary SRS were included in this study. The median tumor volume was 8.7 (IQR 5) cm3. Before SRS, serviceable hearing, facial nerve weakness (House-Brackmann grade > I), and trigeminal neuropathy were present in 205 (33%), 48 (7.7%), and 203 (32.4%) patients, respectively. The median prescription dose was 12 (IQR 1) Gy. At a median radiological follow-up of 38 (IQR 54) months, tumor control was achieved in 94.1% of patients. Early tumor expansion occurred in 67 (10.7%) patients and was associated with a loss of tumor control at the last follow-up (p = 0.001). Serviceable hearing preservation rates at the 5- and 10-year follow-ups were 65% and 44.6%, respectively. Gardner-Robertson class > 1 (p = 0.003) and cochlear dose ≥ 4 Gy (p = 0.02) were risk factors for hearing loss. Facial nerve function deterioration occurred in 19 (3.0%) patients at the last follow-up and was associated with margin doses ≥ 13 Gy (p = 0.03) and early tumor expansion (p = 0.04). Post-SRS, 33 patients developed hydrocephalus requiring shunting. Adverse radiation effects occurred in 92 patients and were managed medically or surgically in 34 and 18 cases, respectively.ConclusionsSRS is a safe and effective method of obtaining tumor control in patients with Koos grade IV VS presenting with non-life-threatening or debilitating symptoms, especially those with surgical comorbidities that contraindicate resection. To decrease the incidence of post-SRS facial palsy, a prescription dose < 13 Gy is recommended.

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