Time course of lesion development in patients with acute brain stem infarction and correlation with NIHSS score

Background and purpose: diffusion weighted magnetic resonance imaging (MRI) is highly sensitive in detecting acute supratentorial cerebral ischemia an d Diffusion Weighted Imaging (DWI) lesion size has been shown to correlate strongly with the neurologic deficit in middle cerebral artery territory st roke. However, data concerning infratentorial strokes area rare. We examine d the size and evolution of acute brain stem ischemic lesions and their rel ationship to neurological outcome. Methods: brain stem infarctions of 11 pa tients were analyzed. We performed DWI in all patients and in 7/11 patients within 24 h. T2W sequences within the first 2 weeks (10/11 patients) and f ollow-up MRI (MR2) within 3-9 months (median 4.8 months) later (12/12 patie nts). Lesion volumes were compared with early and follow-up neurologic defi cit as determined by National Institutes of Health Stroke Scale (NIHSS) sco re. Results: the relative infarct volumes-with MR2 lesion size set to 100%- decreased over the time (P < 0.02) with a mean shrinking factor of 3.3 betw een DWI (MR0) and the follow-up MRT (P < 0.02), and 1.6 between early T2W ( MR1) and MR2 (P < 0.04). The mean DWI volume size (MR0) was larger than the early T2W (P < 0.02). Although neurological outcome was good in all patien ts (mean NIHSS score of 1.3 at follow-up), early NIHSS and follow-up NIHSS scores were strongly correlated (r = 0.9, P < 0.00). NIHSS score at follow- up was highly correlated with lesion size of DWI (MR0; r = 0.71, P < 0.04) and T2W of MR1 (r = 0.86, P < 0.001). Conclusions: in this study, we saw a shrinking of the brain stem infarct volume according to clinical improvemen t of patients. Great extension of restricted diffusion in the acute stage d oes not necessarily implicate a large resulting infarction or a bad clinica l outcome. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.