Impact of Associated Nidal Lesions in Outcome of Brain Arteriovenous Malformations After Radiosurgery with or without Embolization

BACKGROUND: Radiosurgery is a valuable option to treat arteriovenous malformations. There are correlations between some morphologic nidal features and final results, and the benefits of preradiosurgical embolization have not been well established thus far. METHODS: Analysis of a longitudinal cohort of 47 consecutive patients who underwent radiosurgery with or without previous embolization. Embolizations were performed exclusively with n-butyl cyanoacrylate. Radiosurgery was delivered either as a single fraction or divided in up to 5 equal fractions. Clinical and radiologic follow-up of at least 36 months was obtained. Presence of nidal lesions, such as aneurysms, venous outflow stenosis, venous outflow ectasias, and/or intranidal arteriovenous fistulas, were evaluated, and their relation with outcome and complications were studied. RESULTS: Of the patients, 68.1% presented with hemorrhagic event; of these, 62.5% harbored intranidal arteriovenous fistulas, 83.3% had venous ectasias, and 90% had venous outflow stenosis. Occlusion rate of embolization plus radiosurgery was 46.1%, and stereotactic radiosurgery alone was 52.4% (P = 0.671). Variables significantly associated with obliteration were lower nidus volume, lack of intranidal arteriovenous fistula, higher stereotactic radiosurgery dose, and lower radiosurgical-based arteriovenous malformation scale score. CONCLUSIONS: An untreated arteriovenous fistula inside the arteriovenous malformation at the moment of stereotactic radiosurgery was associated with lower cure rates (P = 0.001). Embolization followed by radiosurgery was not superior to radiosurgery alone; however, targeted embolization of intranidal arteriovenous fistulas to increase obliteration rates and to protect the patient from bleeding during the radiosurgery latency period should be considered.