Introduction: The impact of aneurysms on distal cerebral hemodynamics is unknown. Here we examine the relationship between aneurysm size and distal hemodynamics prior to treatment.
Methods: Patients seen at our institution between 2006-2015 with aneurysms within the cavernous or supraclinoid ICA segment (proximal to ICA terminus) were retrospectively reviewed. Only un-ruptured proximal anterior circulation aneurysms were included, patients with contralateral aneurysms were excluded. Patients were included if they had flow volume rate and flow velocities measured prior to any treatment using Quantitative MRA. Pulsatility index (PI) = [(systolic - diastolic flow velocity)/mean flow velocity] was calculated for ipsilateral and contralateral MCA and ICA. Hemodynamic parameters were analyzed with respect to aneurysm size.
Results: 42 patients were included. Mean aneurysm size was 13.5 mm (range 2-40mm). There was significant correlation (Pearson’s) between aneurysm size and ipsilateral MCA PI (P=0.006; r=0.441), MCAipsilateral/ICAipsilateral PI ratio (P=0.003; r=0.57), and MCAipsilateral/MCAcontralateral PI ratio (P=0.008; r=0.43).
Conclusions: Larger aneurysm size is significantly associated with higher ipsilateral MCA PI, demonstrating that aneurysms change distal cerebral hemodynamics. Aneurysm treatment may thus acutely change those altered hemodynamics.