Abstract WP45: Regional Contribution of Salvaged Brain Tissue on Outcome in Endovascular Stroke Therapy

Abstract

Introduction: Endovascular stroke treatments (ET) require an understanding of the relative eloquence of brain regions, particularly when treating distal occlusions. However, prior studies of regional eloquence have focused on the effect of infarcted territories on outcome. Here, we evaluate the relative importance of salvaging different brain regions. Methods: From our prospectively maintained institutional registry, we identified patients treated with ET from 2010-2015 with presentation and day 5-7 MRI scans. Brain regions were defined as follows: initial infarct from presentation ADC (manually identified), penumbra from initial perfusion MRI TMax > 6 seconds, and final infarcts from hyperintense day 5-7 FLAIR regions (manually identified). Salvaged brain tissue (SBT) was computed by co-registering day 5-7 FLAIR with presentation perfusion MRI against the SRI24 Brain Atlas, and calculating the difference between penumbra and final infarct. SBT maps of all patients were combined and weighted against 90-day modified Rankin scale (mRS) to create an outcomes-weighted SBT map. Results: Among 338 patients treated with ET, mean age was 66, 54% were female, and median NIHSS score was 14 [IQR 8-19]. Mean initial infarct was 19 mL (SD 28), final infarct 48 mL (SD 67), and penumbra 414 mL (SD 241). Average SBT was 366 mL (SD 241). SBT volume correlated positively with 90-day mRS (p<0.05). Eloquence maps of SBT brain regions demonstrated differential weighting for the right and left hemisphere (Figure). For both hemispheres, salvaging the Rolandic territory was associated with good outcome, and for the left hemisphere only, salvaging the perisylvian regions (likely representing language areas) was also important. Conclusions: The volume and location of brain tissue salvaged by ET is an important determinant of clinical outcome. The results of our outcomes-weighted salvaged brain tissue maps support targeting eloquent regions when considering a patient for ET.