Changes in pulsatility and resistance indices of cerebral arteriovenous malformation feeder arteries after embolization and surgery

Abstract

Objectives: Embolization reduces flow in cerebral arteriovenous malformations (AVMs) before surgical resection, but changes in pulsatility and resistance indices (PI, RI) are unknown. Here, we measure PI, RI in AVM arterial feeders before and after embolization/surgery.Methods: Records of patients who underwent AVM embolization and surgical resection at our institution between 2007 and 2014 and had PI, RI, and flows obtained using quantitative magnetic resonance angiography were retrospectively reviewed. PI = [(systolic − diastolic flow velocity)/mean flow velocity] and RI = [(systolic − diastolic flow velocity)/systolic flow velocity]. Hemodynamic parameters were compared between the feeder and contralateral artery before and after embolization/surgery.Results: 38 patients were included (6 embolization only, 24 embolization and surgery, 8 surgery only). After embolization, flow volume rates within feeders decreased significantly (p < 0.001) to match flows in their contralateral counterparts (p = 0.78). On the other hand, mean, systolic, and diastolic flow velocities (p = 0.60, 0.32, 0.34, respectively) as well as PI, RI (p = 0.99, 0.68) did not change significantly after embolization. However, after surgery mean, systolic, and diastolic flow velocities within feeders decreased significantly (p = 0.001, 0.002, 0.001, respectively) and PI, RI normalized to match the indices of their contralateral counterparts (p = 0.46, 0.46).Conclusion: Following partial AVM embolization, PI, RI are unchanged and flow velocities in feeder arteries also remain unchanged likely due to redistribution of flow through residual nidus. Thus, staged management of AVMs is unlikely to increase outflow resistance and offers a safe treatment strategy.