Abstract TMP118: Clinical Outcomes of Surgical Resection After Stereotactic Radiosurgery Among Patients With Cerebral Arteriovenous Malformations

Introduction: Surgical treatment of arteriovenous malformations (AVMs), particularly higher grade lesions, can be aided by staged treatment consisting of stereotactic radiosurgery (SRS) followed by surgical resection in a delayed fashion. This strategy can be used to downgrade the AVM S-M grade, reduce blood flow through the AVM and often results in histopathological changes making AVMs more amenable to microsurgical resection. We present our 28-year clinical experience in managing AVMs with pre-operative SRS as a surgical adjunct. Methods: We retrospectively reviewed and analyzed records of all patients treated for cerebral AVMs between February 1991 and July 2019 at our institution. All patients that underwent SRS, with and without embolization, followed by microsurgery were included in the study. Of the 1245 cerebral AVM patients treated at our institution, 62 patients met eligibility criteria. Univariate and multivariate regression analysis was performed where appropriate to examine relationships between key variables and outcomes. Results: The majority of lesions (50%) were high grade (SM 4-5), 28.6% were intermediate (SM 3), while 21.4% were low grade (SM 1-2). Hemorrhage was the presenting sign among 22.6% of patients. Complete resection was achieved among 64.5%, 79% and 82% of patients after first, second and third surgical stages respectively; 16.1% of patients had partial resection requiring further treatment. Radiographic cure was achieved among 53 patients (85.5%), while 8 (12.9%) patients had residual AVM at last follow up. Six of 8 patients without radiographic cure received post-operative SRS. Thirty-seven patients (63.8%) had improved (26, 44.8%) or stable mRS scores (11, 19%), while 21 (36.2%) had a decline in mRS at final follow up compared to mRS at presentation; this includes 4 (6.9%) deaths due to hemorrhage, outside of the perioperative period, but occurring during follow up prior to AVM obliteration. Conclusion: SRS is a useful adjunct in the surgical management of cerebral AVMs. Multimodal therapy allowed for high obliteration rates with acceptable morbidity in this series of patients with predominantly high grade AVMs.