Introduction: Non-vestibular cranial nerve schwannomas represent a rare type of benign intracranial tumor. Few studies have evaluated the use of Gamma Knife stereotactic radiosurgery (SRS) as a primary treatment for these lesions. We report here a large series of patients with SRS-treated non-vestibular schwannomas with a focus on safety and efficacy.
Methods: We performed a retrospective study of patients who underwent SRS at our center for any type of non-vestibular schwannoma and for whom at least 6 months of radiological follow-up was available. The data collected included patient characteristics, clinical symptoms at time of treatment, treatment details, radiological response and clinical evolution and survival.
Results: Data was gathered for a total of 35 schwannomas amongst 34 patients treated between 2004 and 2016 with a median follow-up of 48 months. Median age at time of treatment was 51. Three patients had neurofibromatosis type 2. Schwannoma location was trigeminal in 57.2%, facial in 20%, jugular foramen in 14.3%, abducens in 5.7% and trochlear in 2.9% of patients. The median margin dose was 13 Gy (range, 12-15 Gy), and median treatment volume was 2.1 cc (range, 0.1-8.5 cc). Crude local control was of 100% for trochlear, abducens and jugular foramen schwannomas, and of 95% and 85.7% for trigeminal and facial nerve schwannomas, with one failure amongst 20 and 7 cases respectively. At the last follow-up, clinical symptoms had resolved in 31.4% of patients, improved in 5.7%, remained stable in 40% and worsened in 20%.
Conclusions: SRS is a good modality for the treatment of non-vestibular cranial nerve schwannomas. When compared to the published literature, tumor control rates appear similar to those of vestibular schwannomas and the safety profile appears favorable compared to microsurgical resection.
Patient Care: This study demonstrates the safety of radiosurgery for non-vestibular schwannomas.
Learning Objectives: - Discuss the management of non-vestibular schwannomas