Hypofractionated Stereotactic Radiotherapy in the Treatment of Intracranial Arteriovenous Malformations: A Systematic Review and Single-Arm Meta-Analysis

Introduction: Hypofractionated Stereotactic Radiotherapy (HFSRT) offers promise for the treatment of intracranial arteriovenous malformations (AVMs) in cases when conventional stereotactic radiosurgery is not advised. Conversely, its efficacy and safety are still unclear, leading to the performance of this systematic review and single-arm meta-analysis.

Methods: Following the PRISMA guidelines, we searched PubMed, Embase, Cochrane, and Web of Science to select articles that utilized HFSRT to treat intracranial AVMs. Studies had to report at least one outcome of interest. We did not consider case series featuring fewer than four patients. The assessed outcomes included complete and partial obliteration rates, post-intervention hemorrhagic events, instances of radionecrosis, morbidity and mortality.

Results: A total of 16 studies were included, embracing 461 patients who underwent HFSRT. Regarding the Spetzler-Martin classification, 74% of patients fell within the III-V range. Among the totality of the individuals, intracerebral hemorrhage was the primary symptom in 50.9% of cases. Hemorrhagic events occurred in 0.08 [95% CI: 0.05-0.11, I2 = 3%] of the patients. Complete and partial obliteration rates were also 0.50 [95% CI 0.32-0.69, I2 = 98%] and 0.31 [95% CI 0.13-0.48, I2 = 90%], respectively. The combined morbidity outcomes, considering transient and permanent neurological deficits, new-onset seizures, and cyst formation post-HFSRT, had a reported incidence of 0.16 [95% CI 0.05-0.11, I2 = 0%]. Finally, mortality presented an incidence of 0.03 [95% CI 0.01-0.05, I2 = 16%], while radiological necrosis after HFSRT was reported at 0.05 [95% CI 0.02-0.07, I2 = 0%].

Conclusion : We found low incidence and variability of the safety indicators, such as hemorrhagic events, morbidity, and radiological necrosis. Despite these results, the effectiveness of HFSRT remains unclear and future research is required, encompassing a broader patient population.