The window of safety and efficacy for administering tissue plasminogen activator (tPA), the only FDA-approved medication for stroke, is less than four hours. For patients with “wake-up stroke,” scientists have long been unconvinced that risks of using tPA outweigh the potential health benefits. However, a new study shows tPA is safe for these stroke patients after all.
“Wake-up stroke,” which is literally the instance of an individual waking up with stroke symptoms after falling asleep with no known symptoms, makes up nearly 25 percent of all strokes that occur. Because there is no way for doctors to know when these patients started exhibiting stroke symptoms, they are usually ineligible for tPA. Principal investigator Andrew Barreto, MD, from the University of Texas, has reason to believe that tPA could in fact help these patients avoid irreversible complications from stroke.
“[Upon waking] the body undergoes many changes to prepare itself for wakefulness including elevating the blood pressure by releasing stress hormones," Barreto said. "Without tPA or some other form of restoring blood flow, the majority of these patients will be left with disabling effects."
Barreto and his team studied 40 patients from five stroke centers with wake-up stroke who were also treated with tPA within three hours after waking up. The researchers saw no intracerebral hemorrhaging, a condition believed to be more likely when tPA is administered more than three or four hours after onset of stroke symptoms.
Additionally, at three-month follow-up, over half of the patients achieved “excellent recovery,” according to the modified Rankin Scale, a “global outcomes rating scale for patients post-stroke... used to categorize level of functional independence with reference to pre-stroke activities rather than on observed performance of a specific task.”
tPA, also known as intravenous thrombolysis, works by dissolving blood clots that cause stroke, improving blood flow to the deprived parts of the brain. A 2011 study estimated that only three to five percent of stroke patients reach the hospital in time to be considered eligible for tPA treatment. Overall, strokes are considered to be 80 percent preventable by managing risk factors such as hypertension, cigarette smoking, atrial fibrillation and physical inactivity.
Barreto’s study was recently published in the Annals of Neurology
Sources: The Neurohospitalist
, Baylor University Medical Center Proceedings
, American Stroke Association
, Heart & Stroke Foundation
, University of Texas Health Science Center at Houston