Mini-strokes are thought to be fairly fleeting, often lasting a few minutes with symptoms gone within 24 hours and no apparent lingering effects — although they do heighten a person’s risk of full-blown stroke in the future.
They’re transient, as one might infer from their formal name, transient ischemic attack. They’ve come and gone.
But experiments conducted at a neuroscience lab in British Columbia paint a picture of a more lasting effect.
Researchers used transcranial magnetic stimulation to examine patterns of brain activity in 13 patients who had experienced TIAs 14 to 30 days earlier, and compared them to the brain activity of 13 healthy people.
Lara Boyd, a neuroscientist with the Brain Research Centre at Vancouver Coastal Health Research Institute and the University of British Columbia, said magnetic resonance imaging might or might not reveal a little damaged area or lesion in the brain after a TIA.
“But we wondered if we could maybe detect something with neurophysiology, with electro-physiology, that has previously gone unnoticed,” she said in an interview.
The non-invasive method involves putting a pulse of electrical current into the brain; for example, it allows scientists to measure how much current is needed to cause a motor response, such as a muscle twitch.
“By using some variations on this particular approach, we can then gauge how excitable the brain is,” Boyd said.
It’s already known that after a stroke, the stroke side of the brain is not very excitable because damage causes it to be suppressed or depressed, she said.
And now, the B.C. lab has found essentially the same thing in patients who have had a TIA.
“They’re now supposedly recovered two weeks after that event. We still see the same pattern, or similar pattern, of suppression of the damaged side of the brain,” Boyd said.