Transient Ischemic Attack (TIA)
A Transient Ischemic Attack (TIA), also known as Transient Cerebral Ischemia or “mini-stroke,” is an event in which blood flow to the brain is briefly blocked and then restored before lasting damage occurs. Surgical treatment of the underlying cause may prevent permanent damage. The most common treatment options are carotid endarterectomy (CEA) and carotid artery angioplasty and stenting (CAS). Our neurosurgeons are experienced in these, as well as less common surgical interventions.
Although its symptoms disappear within minutes or hours, a TIA should not be ignored. A person who has had a TIA may be at risk for a full-blown stroke, which can cause permanent brain damage or death. In fact, stroke is the fifth leading cause of death, and the leading cause of disability, among adult Americans.
The symptoms of a TIA depend on the size and location of the blockage. Symptoms may include:
- Sudden confusion and loss of coordination
- Sudden trouble seeing in one or both eyes (e.g. blurry vision, double vision or no vision)
- Sudden weakness or numbness in an arm, leg, or the face
- Sudden severe headache
These are the same as the symptoms of a stroke. Indeed, there is no way to tell during the event whether it is a TIA (in which case the symptoms disappear on their own after blood flow is restored) or a stroke (in which case blood flow is blocked long enough to cause permanent damage). Anyone experiencing any of the symptoms listed above should receive immediate medical attention.
The acronym FAST was created to help people remember a few common signs of stroke:
- Face drooping
- Arm weakness
- Speech slurred
- Time to call 911
There is no single test that can diagnose a TIA. A doctor will take as much information as possible from the patient and his or her family, or anyone who witnessed the TIA. The doctor will perform a thorough physical and neurological exam, looking for weakness, numbness, lack of coordination or trouble speaking or understanding.
In order to diagnose the TIA and rule out many other possible causes of the patient’s symptoms, the following scans may be performed:
- Magnetic resonance imaging (MRI): This test forms pictures of the body’s structures using magnets and radio waves.
- Diffusion-weighted MRI (DW-MRI, or DWI): Performed along with a regular MRI, this test tracks the motion of water molecules to provide even more information about cells in the brain. DW-MRI is more sensitive to early effects of TIA (or stroke) than regular MRI.
- Computed tomography scan (CT scan, or CAT scan): This test forms pictures of the body’s structures using a computer and many X-rays from different angles.
- Angiography: This test uses a dye injected into the bloodstream to form images of blood vessels and investigate blood flow. It may be performed along with CT (a procedure called CT angiography, or CTA) or MRI (a procedure called magnetic resonance angiography, or MRA).
- Carotid ultrasound: This test uses sound waves to form images of the carotid arteries in the neck.
Blood tests may also be performed to check blood sugar levels and blood clotting, and to look for toxins, diseases, or any other possible factors.
Two types of arteries supply blood to the brain, and a blockage in either type can result in a TIA. A blockage in one of the cerebral arteries prevents blood from reaching the portion of the brain ordinarily sustained by that artery. A blockage in one of the carotid arteries causes blood flow problems for the entire brain–not just a single section.
There are three major causes of blockage in either type of artery:
First, in a condition called atherosclerosis, artery walls thicken and stiffen as a result of the presence of plaques. Arterial walls affected by plaques have a reduced space available for blood flow. Atherosclerosis can happen in any artery in the body, including the carotid and cerebral arteries. Atherosclerosis in the carotid arteries is sufficiently widespread and problematic that physicians refer to it by a separate name: carotid artery disease.
Second, in arteries with atherosclerosis, a plaque may burst. A burst plaque sets off a chain reaction that may result in a blood clot. The clot blocks the artery. In a TIA, the clot quickly breaks up on its own, but the same factors might produce a debilitating stroke on another occasion if the clot were to remain intact.
Third, a piece of a clot that forms elsewhere may break off, travel through the bloodstream, and lodge in a vessel that is too narrow for it to pass. (This narrow vessel may either be a cerebral artery–narrow under any circumstances–or a major vessel such as a carotid artery that has been narrowed by atherosclerosis.) Often, such clots come from the heart. Atrial fibrillation is a risk factor for this type of clot.
The vast majority of TIAs are caused by these factors. Occasionally, conditions such as moyamoya syndrome, vasculitis, subdural hematoma, or tumor may cause a TIA.
In general, the risk factors for a TIA are closely related to the risk factors for artery disease and heart disease. They include diabetes, smoking, high blood pressure, and obesity.
The goal of treatment is to prevent a stroke. The foundation of stroke prevention is usually a combination of medication and lifestyle changes.
Surgery may also be required in certain cases, such as in patients with severely narrowed carotid arteries.
The two main surgical treatments for carotid artery disease are carotid endarterectomy (CEA) and carotid artery angioplasty and stenting (CAS). In a CEA, a neurosurgeon opens the artery and physically removes the blockage. In a CAS, a neurosurgeon inserts an instrument that widens the artery and props it open.
TIAs due to rare disorders (such as moyamoya, vasculitis, subdural hematoma, or brain tumor) may need specifically targeted surgical treatment.