Abstract 76: Significance of Paradoxical Central Increased Diffusivity in Perinatal Arterial Ischemic Stroke

Abstract

Objective: Perinatal arterial ischemic stroke (PAS) is diagnosed by MRI in the acute period after clinical presentation (seizure and/or encephalopathy). Acute MRI stroke protocols include diffusion weighted imaging (DWI), and typically show uniformly restricted diffusion. Yet, a periphery of restricted diffusion with a core of central increased diffusivity (CID) is sometimes observed in PAS (Fig. 1). Given the confusing and paradoxical DWI appearance in those patients, we sought to determine CID significance, and hypothesized that: 1) CID is associated with larger strokes 2) CID tissue is irreversibly injured (infarcted) on follow-up imaging, which may portend worse outcome. Methods: We reviewed all PAS cases in our prospective cohort study from 08/01/2000 - 1/01/2012. PAS with DWI in the acute period was identified and assessed for CID by a pediatric neuroradiologist (NVS); confirmation/clinical data abstraction was performed by a pediatric stroke neurologist (JAW). Stroke volumes were measured by drawing regions of interest around the periphery of the area of restricted diffusion on DWI. Mann-Whitney U was performed to compare means between groups. Results: Of 25 PAS cases with satisfactory MR imaging, CID was seen in 4 (16%). Patients with CID had larger average stroke volumes (mean 117182 mm3 vs. 36995 mm3; p=0.008), and were more often treated for ongoing seizures at last clinic follow-up (3/4 vs. 0/21; p<0.00001). All CID patients underwent follow-up imaging (range 4-27 months), and the CID tissue was confirmed to have undergone completed infarction. Conclusion: In our small PAS sample, CID was associated with larger stroke volume; this tissue with paradoxically increased diffusivity was confirmed as infarcted on follow-up imaging. Patients with CID were more commonly treated for persistent seizures beyond the newborn period. Our data suggest that CID on initial MRI may add prognostic significance in newborns with PAS.