A transient ischemic attack (TIA) is a phenomenon caused by a temporary disruption in the blood supply to a part of the brain. Unlike a stroke, the circulatory blockage is brief and there is no brain tissue death (i.e., permanent damage), as the blockage breaks away and dissolves.
A TIA is similar to a stroke and results in stroke-like symptoms; however, TIAs tend to last for only a few minutes or 1-2 hours before fully resolving within 24 hours.
In the days following a TIA, the risk of a stroke increases dramatically; in fact, a third of the people with TIA later have recurrent TIAs and a third have a stroke in the future. Fortunately, one may also consider the occurrence of a TIA as an opportunity to find a cause or minimize the risk to prevent a possible stroke.
The Risk of Stroke after Transient Ischemic Attack
A TIA is characterized by a disrupted blood supply to a region of the brain which very commonly results due to blood clots. These can form in the arteries of the brain (thrombosis) usually following the gradual narrowing of the blood vessel by plaque (a fatty build-up) in a process called atherosclerosis. A blood clot can form if the plaque ruptures, leading to further blockage of the artery.
If a person is suffering from atrial fibrillation, blood clots may float downstream from the heart and get caught in small blood vessels (embolus). Atrial fibrillation is characterized by an uncoordinated heartbeat which allows blood to become stagnant and form small clots that can embolize to any organ in the body, such as the brain.
Due to the complexity of the structure and function of the brain, the resulting deficits are grouped based on the anatomy of the brain.
- Paralysis of different limbs depending on the affected brain region.
- Difficulty in speech or understanding.
- Numbness of a limb, particularly on one side of the body.
- Clumsiness during walking or with certain hand movements.
- Lack of balance and coordination.
- Severe headache.
There are several risk factors for a TIA. Risk increases with age, particularly after age 55. In terms of sex, the risk of both TIA and stroke is slightly higher in males than in females
A prior TIA also makes an individual up to 10 times more likely to have a stroke. Additionally, the risk may generally be greater if a family member has also suffered from a TIA or stroke.
High fat and salt intake, in particular, generally increase weight and can subsequently contribute to the risk of TIA and stroke. Reducing saturated fat and trans fats intake may reduce the plaques in arteries. However, if dietary changes alone do not help, cholesterol-lowering medications, such as statins, may be prescribed.
The preexistence of certain cardiovascular diseases including heart failure, heart defects, heart infections, or abnormal heart rhythm, also puts an individual at a greater risk of a TIA. Diabetes is also a significant risk factor, as this condition can increase the severity of atherosclerosis and speed of its progression.
Elevated homocysteine, which is an amino acid in the blood that can cause arteries to thicken and scar, can also contribute to the risk of a TIA by increasing the individual's susceptibility to clots.
Cigarette smoking also increases the risk of blood clots, elevates blood pressure, and contributes to the development of atherosclerosis. Additionally, alcohol intake should be limited to a maximum of two drinks daily for a man and one drink daily for a woman.
Following a TIA, several different tests can be performed. An angiogram, for example, can help to determine if there is vessel blockage or bleeding. An ultrasound can also be used to check for the narrowing of arteries.
An echocardiogram (echo) can also be used after a TIA has occurred to check the blood flow through the heart and detect the presence of any blood clots. An electrocardiogram (ECG) and heart rhythm test can also be used to ensure a regular heartbeat.
Cholesterol and triglycerides tests may also be ordered, as the elevation of these biomarkers can indicate an increased risk of blood clots and atherosclerosis.
Importantly, while a computed tomography (CT) or magnetic resonance imaging (MRI) scan of the brain will almost always be ordered, a stroke may show changes where a TIA will not.