Predicting outcome in acute stroke

The natural history of acute stroke is well defined. Predicting outcome in individuals, however, remains difficult, because prognostic studies examini ng associations between clinical signs or syndromes and outcome differ in p atient selection, timing and choice of neurological assessments and outcome measures. Accuracy has been disappointing. Osler in 1892 stated that the ' course of the disease... is dependent on the situation and extent of the le sion'. Until recently, it has not been possible to examine the stroke progn osis, using Osler's approach, with any great accuracy. The advent of diffus ion weighted magnetic resonance imaging (DWI), which is highly sensitive to the pathophysiological changes underlying stroke, offers this possibility as it measures the site and extent of irreversible infarction. This review summarises the results of syndrome or sign-based predictive studies and sho ws how DWI may explain different outcomes in patients with identical neurol ogical presentations, according to the 'situation and extent of the lesion' .