Acute stroke subtypes--is there a need for reclassification?

Abstract

Although stroke covers a wide range of diseases and aetiologies, it is currently managed using uniform treatments, such as thrombolysis and neuroprotective drugs, irrespective of the individual stroke pathophysiology. The time-consuming, ineffective and often misleading standard work-up of stroke subtypes is now being augmented with immediate brain and vessel imaging studies and laboratory testing. This approach means that, in addition to distinguishing between haemorrhagic and ischaemic lesions, ischaemic lesions can be assigned to various stroke subtypes. Diffusion-weighted magnetic resonance imaging is useful to detect the cytotoxic oedema occurring early in cerebral ischaemia, and sequential studies are useful in evaluating each patient's prognosis. Both this technique and magnetic resonance angiography are effective in the assessment of an optimal selection of therapy in early stroke. Particular benefit is derived by patients with recent infarction and overlapping signs and symptoms of residual and acute deficits, and those with more than one aetiology. Demonstration of very small versus large ischaemic territories supports the likelihood of a good spontaneous outcome and discourages high-risk treatment procedures. Chronic and acute lesions may be differentiated and potentially salvageable tissue identified in cases of embolic stroke. The micro-embolic nature of lesions formed by the fragmentation of more proximal intracranial artery occlusions may be revealed by ultrasound studies showing high-intensity transient signals. Results from such studies are also useful to re-evaluate present concepts of stroke subtypes: recent data suggest that the 'border zone infarction' concept needs to be largely abandoned.