Middle cerebral artery flow velocity increases more in patients with delayed intraparenchymal hemorrhage after Pipeline

Pipeline Embolization Devices (PED) are commonly used for endovascular treatment of cerebral aneurysms but can be associated with delayed ipsilateral intraparenchymal hemorrhage (DIPH). The role that altered intracranial hemodynamics may play in the pathophysiology of DIPH is poorly understood. We assess middle cerebral artery (MCA) flow velocity changes after PED deployment.Patients with aneurysms located proximal to the internal carotid artery terminus treated with PED at our institution between 2015 and 2016 were retrospectively reviewed. Patients were included if MCA flow velocities were measured using transcranial Doppler. Bilateral MCA flow velocities, ratio of ipsilateral to contralateral MCA flow velocity, and bilateral MCA pulsatility index before and after PED deployment were assessed.10 patients of mean age 52 years were included. Two patients had DIPH within 48 hours after PED deployment. We observed that these two patients had a higher increase in ipsilateral MCA mean flow velocity after treatment compared with patients without DIPH (39.5% vs 5.5%). Additionally, before PED deployment, patients with DIPH had a higher ipsilateral MCA pulsatility index (1.55 vs 0.98) and a higher ratio of ipsilateral to contralateral MCA mean flow velocity (1.35 vs 1.04).After PED, ipsilateral MCA mean flow velocity increases more in patients with DIPH. These flow velocity changes suggest the possible role of altered distal intracranial hemodynamics in DIPH after PED treatment of cerebral aneurysms. Further data are required to confirm this observation.