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

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Winner of the Louise Eisenhardt Traveling Scholarship, Sophia F Shakur, presented her research—Changes in Pulsatility and Resistance Indices of Cerebral Arteriovenous Malformation Feeder Arteries after Embolization and Surgery—during the 2016 American Association of Neurological Surgeons (AANS) Annual Scientific Meeting.

Embolisation reduces flow in cerebral arteriovenous malformations (AVMs) before surgical resection, but changes in pulsatility and resistance indices (PI=[(systolic – diastolic flow velocity)/mean flow velocity], RI=[(systolic – diastolic flow velocity)/systolic flow velocity]) are unknown. The authors measured PI, RI in AVM arterial feeders pre- and post-embolisation and/or surgery.

The study reviewed records of patients who underwent AVM embolisation and surgical resection at a single institution between 2007-2014, and those patients who had PI, RI and flows obtained using quantitative magnetic resonance angiography were retrospectively reviewed. Haemodynamic parameters were compared between the feeder and contralateral artery pre- and post-embolisation/surgery.

32 patients with 48 feeder arteries underwent embolisation (mean 1.3 sessions). Another 32 patients with 49 feeder arteries had surgery with/without preoperative embolisation. Before any treatment, flow volume rate and mean, systolic, diastolic flow velocities were significantly higher in feeders versus contralateral counterparts, and PI, RI were significantly lower in feeder compared to contralateral vessels. After embolisation, mean, systolic and diastolic flow velocities increased significantly, but PI, RI did not change significantly. However, after surgery mean, systolic and diastolic flow velocities within feeders decreased significantly, and PI, RI normalised to match the indices of their contralateral counterparts

Following partial AVM embolisation, PI, RI are unchanged, and flow velocities in feeder arteries increase significantly, likely due to redistribution of flow through residual nidus. Complete surgical resection results in normalisation of PI, RI and a concomitant decrease in flow velocities.