Early results of radiosurgical treatment of patients with non-vestibular intracranial schwannomas

Abstract

Non-vestibular schwannomas constitute a rare group of intracranial tumors. Surgical removal is associated with technical difficulties and a high risk of permanent dysfunction of the cranial nerves involved. Radiosurgery is an alternative method for treating intracranial tumors of various locations. Purpose of the study. Analysis of the effectiveness of radiosurgical treatment of patients with non-vestibular schwannomas. Material and methods. From March 2018 to February 2023, 19 patients with tumors of the cranial nerves, excluding vestibular schwannomas, were treated at the Gamma Clinic. One facial nerve tumor was removed and verified as a malignant nerve sheath tumor 6 months after SRS. The mean age of the patients was 46.6 years, with 6 men and 13 women. The average tumor volume before treatment was 4.0 cm3 (0.1–8.4 cm3). Radiation treatment was carried out using the Leksell Gamma Knife Perfexion. The analysis of tumor dynamics after irradiation was carried out by volumetric comparison on control MRIs. Neurological dynamics were assessed based on a face-to-face examination of the patients or based on the results of a telephone survey during remote follow-up. Results. Fifteen patients were available for outcome assessment. Median follow-up was 37.9 months (CI 95 % 12.1–50.2). In 10 patients, a decrease in tumor was noted at the time of the last MRI; in 5 patients, an increase in tumor volume was detected. Thus, tumor growth control was achieved in 10 out of 15 cases (66.6 %). Clinical symptoms regressed or remained stable in 11 cases; in other 4 patients, a temporary increase in clinical symptoms was noted due to transient post-radiation tumor enlargement, with a further decrease in symptoms to the initial level due to tumor reduction or steroid therapy. There was no persistent aggravation of symptoms after SRS. Conclusions: Stereotactic radiosurgery is an effective and safe treatment method for non-vestibular schwannomas. Given the phenomenon of post-radiation pseudoprogression, longer follow-up is required to assess tumor growth control.