The treatment of stroke patients has been characterized by the need for speed. The only medical therapy available, a clot dissolving drug called tPA, was originally available for use only if it could be given less than 3 hours after the start of symptoms. This led to the development of stroke centers to treat patients as rapidly as possible. Ten years ago the time was extended to 4.5 hours for some patients.

In recent years, another type of stroke treatment has been developed known as endovascular thrombectomy. In this procedure, a catheter is guided into a brain artery, and a device is used to pull a clot out of the brain. In 2015, this procedure was demonstrated to benefit patients with the most severe strokes, those due to large clots, up to 6 hours after the start of symptoms.

Researchers have been working for years to find a way to identify patients who would benefit from later treatment. These patients, who are suffering a stroke due to a lack of blood flow to the brain, are those who have not yet suffered significant damage.  

A breakthrough advance in the selection of stroke patients for therapy is  software that is able to analyze special CT scan images, known as CT perfusion. This software can automatically determine which patients have a small area of permanent damage, and an area that can be potentially saved by available treatments. 

Using one type of software, known as RAPID, it has now been demonstrated in multiple stroke studies performed around the world that some patients may be treated with thrombectomy up to 24 hours. Only during the past month researchers from Australia showed that using this software, some patients can be successfuly treated with tPA up to 9 hours following the beginning of stroke symptoms.

As this software, and others like it, come into more common use, more stroke patients will be treated later and more effectively.
Thrombectomy is being performed up to 24 hours in many stroke centers, and in the future, the window for tPA is expected to be extended.