Transient ischemic attacks may predate full stroke by as much as seven days, making it all the more important that physicians teach at-risk patients about typical symptoms and the need to present immediately for evaluation, according to an article in the March 8th issue of the journal Neurology.

Roughly 80 percent of strokes are ischemic, and many are preceded by transient ischemic attacks, in which symptoms may disappear within 5 minutes or so.

The study examined 2,416 people who survived an ischemic stroke. In 549 patients, transient ischemic attacks were experienced prior to the ischemic stroke and, in most cases, within the preceding seven days: 17 percent occurred on the day of the stroke, 9 percent on the previous day, and 43 percent at some point during the seven days prior to the stroke.

“We have known for some time that transient ischemic attacks (TIAs) are often a precursor to a major stroke,” said study author Peter M. Rothwell, MD. “What we haven’t been able to determine is how urgently patients must be assessed following a TIA in order to receive the most effective preventive treatment. This study indicates that the timing of a TIA is critical, and the most effective treatments should be initiated within hours of a TIA in order to prevent a major attack.”

Rothwell also noted that clinical guidelines should be amended accordingly.

The study included two population-based studies (Oxford Vascular Study and Oxfordshire Community Stroke Project) as well as two randomized trials (UK-TIA Aspirin Trial and European Carotid Surgery Trial).