STUDIES OF ACUTE ISCHEMIC STROKE WITH PROTON MAGNETIC-RESONANCE SPECTROSCOPY - RELATION BETWEEN TIME FROM ONSET, NEUROLOGICAL DEFICIT, METABOLITE ABNORMALITIES IN THE INFARCT, BLOOD-FLOW, AND CLINICAL OUTCOME

Background and Purpose-Proton magnetic resonance spectroscopy (MRS) ca n be used to study metabolite abnormalities in the brains of stroke pa tients. We have used it to examine the relations between the metabolit es in the infarct (N-acetylaspartate [NAA] and lactate) and the time l apse from stroke to MRS, the presenting neurological deficit, infarct size and swelling (on MRI), blood now to the infarct (estimated by tra nscranial Doppler ultrasound), and clinical outcome. Methods-Patients with symptoms of a moderate to large cortical infarct underwent serial proton MRS (Siemens 1.5 Magnetom) within 4 days, from 5 to 10, and fr om 11 to 35 days after the stroke. A long echo time PRESS single voxel or chemical shift imaging acquisition was used. Transcranial Doppler ultrasound was performed daily in the first week and twice per week th ereafter until the final MRS. Clinical features and baseline demograph ic data were collected independently by a stroke physician and 6-month outcome by postal questionnaire. Results-Fifty patients underwent at least 1 MRS examination, Reduced NAA in the infarct within the first 4 days was related to the clinical stroke syndrome, more extensive infa rction, more severely reduced blood supply to the infarct, and the pre sence of lactate. The presence of lactate was related to large infarct s and reduced NAA. Swelling in the infarct was most closely associated with large infarcts and reduced blood supply but not reduced NAA or t he presence of lactate. Clinical outcome was most closely related to t he extent of the infarct (more than to the clinical syndrome) -the lar ger the infarct the worse the outcome-but not to the metabolite concen trations alone. Conclusions-The reduction in NAA (but not the presence of lactate) in a visible infarct was related to the reduction in bloo d flow to the infarct, which in turn was related to infarct extent and clinical outcome.