About 600,000 strokes are reported each year in the US, and about 150,000 people die as a result. This makes stroke the third-leading cause of death in the nation, and a leading cause of long-term disability. On the brighter side, when symptoms are recognized and people get to a hospital quickly, treating certain strokes within an hour or so can help mitigate the severity of disability.

Transient ischemic attacks (TIAs), also referred to as “light strokes,” or “mini-strokes,” can be early warning signs of an impending stroke. TIAs are caused by a temporary lack of oxygen to the brain that does not cause permanent damage. Between 15% and 30% of all people who have an ischemic stroke (strokes caused by a blocked blood vessel) report a preceding TIA.

If TIAs are recognized and receive prompt assessment and treatment, a subsequent full-blown stroke may become less likely. But until now, medical experts haven’t been certain how soon after a TIA people are likely to experience a stroke, nor, consequently, how soon patients must receive medical attention in order for it to do the most good. Is it a matter of days, hours, or weeks? As it stands, many U.S. guidelines recommend assessment and treatment within one week of a TIA, while those in the UK and other countries recommend treatment within two weeks or more. This difference may reflect more on the availability of resources than on scientific evidence.

A study published in the March 8, 2005 issue of Neurology looked at participants from four different European trials and found that 23% of the participants’ strokes were preceded by at least one TIA and, of those, nearly 45% were preceded by a TIA within only a week.

About the Study

Researchers recruited people who had an ischemic stroke from four independent studies performed in Europe from 1979 to 2003. A neurologist examined eligible participants and details of any previous TIAs or strokes were collected from patient interviews and medical records. In most cases, participants underwent CT brain imaging to confirm their stroke.

The researchers’ assessed time from most recent TIA to stroke, as well as time from first-ever TIA to stroke. They also considered other factors that might have had an impact on the time between TIA and stroke (i.e., age; sex; location, number, and duration of previous TIAs; chest pain; heart attack; diabetes; smoking; peripheral vascular disease; and high blood pressure).

The Findings

The key outcomes of the study were:

  • Of 2,416 patients who presented with an ischemic stroke in the four studies under examination, 549 (23%) reported a history of a preceding TIA.
  • Timing between TIA and stroke was consistent across all fours studies. On average, 17% of the most-recent TIAs occurred on the same day as the stroke, 9% on the day before the stroke, and 43% at some point within seven days of the stroke.
  • In 70% of participants who experienced a TIA within a week of the stroke, it was their first-ever stroke.
  • In 92% of participants who experienced a TIA within a week of the stroke, the TIA and stroke occurred in the same vascular region in the brain.

The researchers failed to identify any defining characteristics of patients that might have influenced how soon after TIA stroke occurred. They also found no reliable indicator that would help distinguish between the TIAs of participants who suffered subsequent stroke and those who did not.

While these findings are informative, they were limited because the study relied in part on self-reported medical history, which can always be faulty. Self-report of past symptoms (e.g., qualities and timing of any TIAs) by participants who have just experienced stroke may be even less reliable than usual.

How Does This Affect You?

This study supports existing evidence that TIAs may act as warning signs of a stroke to come. More importantly, it suggests that for many patients, the window of time to act is narrow: TIAs should be assessed in a matter of days—not weeks.

After a TIA, there may not be enough time for a patient to rely solely on reducing the risk factors of stroke—hypertension, cigarette smoking, high cholesterol, diabetes, and heavy alcohol use. Instead, if you experience a TIA or observe symptoms in someone else, go directly to the hospital, where preventive measures can be taken immediately, such as the use of antiplatelet agents, anticoagulation, carotid endarterectomy, and a number of other methods currently being researched.

Because timing is so crucial, it’s a good idea to keep in mind the following common symptoms of a TIA or stroke, which come on very suddenly:

  • Numbness or weakness of the face, arm, or leg (especially on one side of the body)
  • Confusion, or trouble speaking or understanding speech
  • Trouble seeing in one or both eyes
  • Difficulty walking, dizziness, or loss of balance or coordination
  • Sudden severe headache with no known cause