Stroke--acute interventions

Abstract

The reduction of blood flow to parts of the brain is the cause of ischemic stroke leading to functional deficits and, if prolonged, to irreversible neurological and morphological defects. The fast reperfusion, therefore is the most important therapeutic strategy and was proven to be effective in clinical trials. Steps to intervene with secondary biochemical, molecular, or inflammatory disturbances were not successful so far. Since direct therapeutic interventions are limited, the general management of the stroke victim is of utmost importance--and was shown to be most successful in dedicated stroke units. Acute therapeutic interventions in ischemic stroke can only be successful as long as tissue in the area of the ischemic compromise is still viable. The area of irreversible damage can be identified and distinguished from the penumbral zone, i.e., tissue with impaired function but preserved morphology by functional imaging modalities, like positron emission tomography (PET) or perfusion-(PW) and diffusion-weighted (DW) magnetic resonance imaging (MRI). In such studies it was demonstrated that a large portion of the final infarct is irreversibly affected in the first few hours in many patients. A considerable tissue volume is viable but critically hypoperfused; a smaller portion of the final infarct is sufficiently perfused and in this area secondary and delayed biochemical and molecular mechanisms contribute to the damage. Based on this concept the improvement of perfusion within the time window of opportunity must be the primary goal in treatment of ischemic stroke, and neuroprotective and other strategies can only play a supportive and additive role. That this is the case can be seen from the results of many controlled therapeutic trials, in which up to now only thrombolytic therapy with a 3 h time window for systemic and a 6 h time window for intraarterial application proved its efficacy, whereas all trials with neuroprotective, anti-inflammatory or anti-apoptotic strategies failed. Since the direct treatment strategies are limited the acute management of stroke victims is of utmost importance: This can be achieved optimally in dedicated stroke units in which the outcome was significantly improved over the regular care. It is still to be investigated if invasive strategies--e.g., craniectomy and hypothermia--or the combination of reperfusion and neuroprotective therapy can improve the outcome after ischemic stroke.