What is the window during which thrombolytic therapy can be given for acute ischemic stroke?

Thrombolytic therapy for acute ischemic stroke is most effective when administered within the first three hours of symptom onset. This time window is critical because the likelihood of reversing the neurological deficits caused by a stroke decreases significantly after this period. Studies have shown substantial benefits in functional outcomes when thrombolytics are given within three hours, making it the standard time frame for treatment initiation.

The reasoning behind the three-hour limit is based on the pathophysiology of stroke and the principles of brain tissue viability. Neurons begin to die quickly after the onset of ischemia, and early intervention can help restore blood flow and minimize permanent damage. While some protocols allow for treatment up to four and a half hours in select patients, the established guideline emphasizes three hours as the most critical window for thrombolytic therapy.

Longer windows, such as six or 24 hours, significantly increase the risk of complications and poor outcomes, as the opportunity to salvage brain tissue diminishes over time.