TIAs May Be More Like Stroke Than We Think
Scientists have documented something never seen before: the brain damage associated with transient ischemic attacks (TIAs) is not so transient. In fact, according to a leading neuroscientist, Dr. Lara Boyd, at Vancouver Coastal Health and the University of British Columbia, “we are not sure if the brain ever recovers.”
TIAs, or mini strokes, have lasting effects
The American Heart Association reports that a TIA is a warning sign that “produces stroke-like symptoms but no lasting damage” and that “unlike stroke, when a TIA is over, there’s no injury to the brain.” But the findings of new study appear to make these statements obsolete.
Boyd and her team evaluated 13 patients form the Stroke Prevention Clinic at Vancouver General Hospital along with 13 healthy controls. All the people who had had a TIA experienced some effect on their motor systems but their symptoms resolved within 24 hours. These individuals were then studied within 14 to 30 days of the TIA through clinical evaluation or standard magnetic resonance imaging or computed tomography and showed no impairment.
However, when they underwent a brain mapping procedure that utilizes transcranial magnetic stimulation, the researchers found “that the TIA is actually causing damage to the brain that lasts much longer than we previously thought it did,” according to Boyd, who even suggested that the brain may not ever recover from the injury.
Specifically, the team found that the brain cells on the side of the brain affected by the TIA had undergone changes that made it more difficult for two opposing types of cells, excitatory and inhibitory, to respond as compared with the undamaged side of the brain and with the brains of healthy individuals.
TIAs are important in predicting if a stroke will occur but not when one will happen. In about 50 percent of people who experience a TIA, a stroke occurs within one year. Stroke is the third cause of death in the United States and the leading cause of disability.
Dr. Philip Teal, head of the Stroke Prevention Clinic at Vancouver General Hospital and co-author of the study, emphasized that their finding that TIAs can cause long-lasting effects is “very important” because “by refining this brain mapping technique, our hope is to identify who is most at risk, and direct treatment more appropriately.”
American Heart Association
Edwards JD et al. Stroke 2011 Jan; doi: 10.1161/STROKEAHA.110.602938