Abstract W P32: CSF Volumetric Analysis Reliably Quantifies Cerebral Edema And Correlates With Clinical Deterioration In Large Hemispheric Infarcts

Abstract

Background: Large hemispheric infarcts (LHI) may be complicated by cerebral edema. Midline shift (MLS), a standard radiographic measure, only crudely estimates extent of edema. Volumetric analysis of CSF compartments over time may provide a reliable and accurate means of quantifying severity and kinetics of edema after LHI. Methods: We retrospectively identified stroke patients with NIHSS≥8 and baseline CT within 6 hours who developed cerebral edema (without hemorrhage) on follow-up (FU) CTs. Two raters outlined the sulci and lateral ventricles ipsilateral (IL) and contralateral (CL) to the infarct on baseline and serial FU CTs (both within 48 hours and at peak edema, 2-5 days post-stroke) and quantified CSF and infarct volumes. Changes in compartment volumes from baseline to peak edema CT were correlated with MLS and edema-related neurologic worsening (need for hemicraniectomy, osmotic therapy, or decline in GCS, associated with MLS≥5mm). Results: Ten patients were analyzed (median NIHSS 14, time to early FU CT 30 hours, IQR 15-37 and to peak edema CT 75 hours, IQR 64-95). Inter-rater reliability for volume measures was excellent (intraclass correlation >0.97). CSF volume diminished by 37±20% (49 ml) from baseline to peak edema, over half occurring within 48 hours; net decline in CSF volume correlated with infarct volume (r=-0.63,p=0.05). Greatest reductions in CSF were seen in IL sulci and IL ventricles (Figure, top), but it was % reduction in CL sulci that correlated best with MLS (Fig, bottom), even adjusting for infarct volume (p=0.02). Decline in volumes of IL and CL sulci were greater in the 5 subjects with neurological worsening (89% vs. 56% and 40% vs. 3%, p<0.05), while infarct volume was not. Conclusions: CSF volumetrics is a reliable tool for quantifying cerebral edema after LHI and a novel method of studying edema kinetics. Loss of sulcal volume correlates with MLS and is more strongly associated with edema-related deterioration than infarct volume alone.