Gamma knife radiosurgery for cavernous malformations: a comprehensive study on symptom relief, hemorrhage rates, and histopathological changes

This study aims to demonstrate the effect of gamma knife radiosurgery (GKRS) on symptoms, hemorrhage rates, and histopathological changes in patients with cavernous malformations (CMs), regardless of whether the symptomatic lesions are hemorrhagic. This single-center retrospective study evaluated symptomatic patients with single CMs treated with GKRS between 2016 and 2023. The patients' demographic data, presenting symptoms, GKRS radiation dose, complications developed during follow-up (hemorrhage, radiotoxicity), the rate of symptom improvement, and histopathological changes of surgically removed CMs were recorded. Our study included 134 symptomatic patients, of whom 55 were male (41%) and 79 were female (59%). Among the patients, 80 (59.7%) had CMs in the lobar region, 23 (17.1%) in the cerebellum, 16 (12%) in the brainstem, and 15 (11.2%) in the basal nuclei/thalamus. The mean target volume was 0.64 +/- 1.23 cm3, and the mean tumor margin dose was 14.89 +/- 1.90 Gy. Symptoms were completely recovered in 95 patients (70.9%), while 18 (13.4%) experienced partial recovery. The annual hemorrhage rate (AHR) reduced from 6.26 to 1.01 following GKRS. Adverse radiation effects (ARE) were encountered in ten patients (7.46%) of cases, with only three patients (2.2%) being permanent. The mean follow-up period was 35.57 +/- 23.54 months (2-83 months). Two patients without hemorrhage underwent surgical removal of CM due to symptomatic deterioration after GKRS. Histopathological examination demonstrated numerous vascular structures with luminal narrowing due to hyalinization and fibrinoid necrosis caused after GKRS. Our findings suggest that GKRS may help reduce hemorrhage rates and potentially relieve symptoms in patients with symptomatic CMs, although further long-term studies are necessary to confirm these observations and to fully assess potential risks. Since there is no radiological method to evaluate the impact of GKRS on CMs, our study examines the histopathological changes that occurred following the GKRS. The histopathological changes prove that GKRS alters the morphology of the CMs and thus can relieve symptoms and reduce hemorrhage rates associated with CMs.