A Picture of Strokes to Come — and How to Prevent Them

Stroke recurrence may be predicted from CT scan images taken shortly after mild strokes

(RxWiki News) A picture of your brain after you've had a mini-stroke may show doctors your risk of having another stroke. And you can take steps to lower that risk.

Having a mini-stroke puts you at risk of having a bigger stroke. Images of the brain shortly after a mini-stroke may foretell whether another stroke is on the way, a new study found.

"A stroke is when an artery in the brain gets [blocked], resulting in injury to the part of the brain that it supplies," said Sadat A. Shamim, MD, director of Inpatient Neurology and Neurophysiology at Baylor University Medical Center in Dallas. "Sometimes, the stroke is in a functionally silent part of the brain, so the symptoms are minimal or no injury occurs because the blockage clears up quickly and patients are told loosely that they had a "mini stroke.'"

Dr. Shamim explained that if the stroke did not damage tissue, doctors describe the event as a transient ischemic attack, or TIA.

"You can see that a stroke, mini-stroke and TIA are all spectrums of the same disease and the only thing that separates them is luck," said Dr. Shamim, who was not involved in this study.

"Having a stroke or TIA can increase the risk of subsequent stroke. Because symptoms have resolved, people may have a tendency to ignore TIAs. This study supports the idea that a TIA may be a harbinger to more events to come and early work-up with imaging and other studies may help in implementing risk reduction strategies that could prevent a devastating event," he said.

Patients who have had a mini-stroke or non-disabling stroke can make lifestyle changes to avoid having a second, more damaging stroke. Eating a healthy diet, exercising, maintaining a normal weight and quitting smoking are all steps that can keep a stroke away. Medications can also control stroke risk factors.

CT scans of the brain may establish a patient’s risk of having a second stroke. This imaging done within 24 hours of a mild stroke event may establish the risk level of a patient and when symptoms may worsen, said Jeffrey J. Perry, MD, senior author of this study and associate professor of emergency medicine at the University of Ottawa in Canada, and colleagues.

“All patients should get a CT scan of their brain after a [transient ischemic attack] or non-disabling stroke,” Dr. Perry said in a press release. “Images can help healthcare professionals identify patterns of damage associated with different levels of risk for a subsequent stroke or help predict when symptoms may get worse.”

An ischemic stroke occurs when a blood clot blocks blood from flowing to the brain. A transient ischemic attack, or mini-stroke, is a temporary blockage. With a mini-stroke, blood flow is usually interrupted for only a few minutes and causes no permanent damage, according to the American Stroke Association. The Mayo Clinic says a mini-stroke can be a warning of an impending stroke. It can serve as an opportunity to take steps to prevent a full stroke.

"Anyone who thinks they may be having a stroke or had a TIA (remember 'FAST': Face droop, Arm weakness, Speech difficulty, Time is of essence) should seek urgent medical care because a mini stroke can worsen and a TIA may recur with a stroke," said Dr. Shamim.

"Reducing the risk of stroke after having a TIA involves improving vascular health by possibly taking a daily aspirin, cholesterol medication, [quitting] smoking, weight loss, diabetes control and exercise. Testing also evaluates for other causes that may require treatments with stronger blood thinners and even surgery," he said.

About 1 in 3 people who have a mini-stroke will eventually have a stroke, with about half occurring within a year of the mini-stroke, the Mayo Clinic reports.

CT (computed tomography) is a popular imaging technique that uses special X-ray equipment to make cross-sectional pictures of the body.

Dr. Perry and team looked at 2,028 patients who had mini-strokes. All received a CT scan within 24 hours of their attack. These researchers observed brain damage due to impaired circulation in 814 (about 40 percent).

The overall stroke rate among these patients was 3.4 percent at 90 days and 1.5 percent at two days or fewer.

"We assessed 90 days because most subsequent strokes will happen within this time," Dr. Perry told dailyRx News. "We chose two days (48 hours) because previous studies have found that half of the subsequent strokes will happen within two days."

Dr. Perry and team assessed the chance of another stroke occurring within 90 days according to the level of damage they observed. If the CT image revealed newly damaged tissue due to poor circulation (acute ischemia), a patient had a 2.6 times greater risk of stroke than those without ischemia.

If the CT scan showed previously damaged tissue (chronic ischemia) in addition to acute ischemia, that risk rose to 5.35 times greater than those without damage.

If any type of small vessel damage in the brain was observed in addition to acute ischemia, a patient had a 4.9 times greater risk of stroke than those without ischemia.

Microangiopathy, or a narrowing of the small vessels, is an example of small vessel damage.

If patients had a combination of acute and chronic ischemia along with microangiopathy, the probability of having another stroke was about eight times greater than those who didn't have these conditions.

“These findings should prompt physicians to be more aggressive in managing patients with [mini-strokes] or non-disabling stroke who are diagnosed with acute ischemia, especially if there is additional chronic ischemia and/or microangiopathy,” Dr. Perry said.

Dr. Perry and team said CT imaging can help doctors determine what steps might help patients avoid a new stroke. These measures may include heart monitoring or taking medications to lower blood pressure, treat high cholesterol or prevent blood clots.

This study was published Dec. 4 in the journal Stroke.

The Canadian Institutes for Health Research funded this study. The authors disclosed no conflicts of interest.

Review Date: 
December 6, 2014