The window for stroke therapy refers to the time limit after the onset of symptoms when treatment can still be made available. A new study, presented at the European Stroke Organization conference in Prague last month, may extend this window to 24 hours for carefully selected patients. The trial, known as DAWN, selected patients for treatment between 6-24 hours following ischemic stroke. The investigators performed special CT scan or MRI studies to determine which patients had a small area of established damage, but a larger area of potential damage. These patients received endovascular therapy, where a catheter is manipulated into a brain artery, and a retrieval device is used to clear the clot.

The patients treated with endovascular therapy had a 73% reduction in their chance of being dependent following treatment.

The results of this trial carry great importance. Although they pertain to only a very small percentage of stroke patients (these patients were very highly selected), they establish that all strokes do not progress at the same speed, and that for some patients the time on the clock is less important than characteristics of the stroke that can be learned from the appropriate advanced imaging.

These results will be studied and reviewed by experts in the field, and may result in changes in treatment recommendations in the world’s leading medical systems.