Transiant Ischemic Attack
Also Known As: Transiant Ischemic Attack, TIA, Mini Stoke
A transient ischemic attack (spelled ischaemic in British English) (abbreviated as TIA, often referred to as mini stroke) is a transient episode of neurologic dysfunction caused by ischemia (loss of blood flow) – either focal brain, spinal cord or retinal – without acute infarction (tissue death). TIAs share the same underlying etiology (cause) as strokes: a disruption of cerebral blood flow (CBF). TIAs and strokes cause the same symptoms, such as contralateral paralysis (opposite side of body from affected brain hemisphere) or sudden weakness or numbness. A TIA may cause sudden dimming or loss of vision (amaurosis fugax), aphasia, slurred speech and mental confusion. But unlike a stroke, the symptoms of a TIA can resolve within a few minutes or 24 hours. Brain injury may still occur in a TIA lasting only a few minutes. Having a TIA is a risk factor for eventually having a stroke or a silent stroke. A silent stroke or silent cerebral infarct (SCI) differs from a TIA in that there are no immediately observable symptoms. A SCI may still cause long lasting neurological dysfunction affecting such areas as mood, personality and cognition. A SCI often occurs before or after a TIA or major stroke.
The most common cause of a TIA is an embolus that occludes an artery in the brain. This usually arises from a dislodged atherosclerotic plaque in one of the carotid arteries (i.e. a number of major arteries in the head and neck) or from a thrombus (i.e. a blood clot) in the heart because of atrial fibrillation. In a TIA, the blockage period is very short-lived and hence there is no permanent damage. The cholesterol build-up is gradual and eventually narrows the lumen. With time, blood flow to that side of the brain is reduced and a stroke may result. In other cases, cholesterol particles from the atherosclerotic plaque may suddenly break off and enter the brain. In some people, these fragments come off from the heart and go to the brain. This often happens during a heart attack or an infection of the valves.
Other reasons include excessive narrowing of large vessels resulting from an atherosclerotic plaque and increased blood viscosity caused by some blood diseases. TIA is related to other medical conditions such as hypertension, heart disease (especially atrial fibrillation), migraine, cigarette smoking, hypercholesterolemia, and diabetes mellitus.
Symptoms vary widely from person to person, depending on the area of the brain involved. The most frequent symptoms include temporary loss of vision (typically amaurosis fugax); difficulty speaking (aphasia); weakness on one side of the body (hemiparesis); and numbness or tingling (paresthesia), usually on one side of the body. Impairment of consciousness is very uncommon. There have been cases of temporary and partial paralysis affecting the face and tongue of the afflicted. The symptoms of a TIA are short-lived and usually last a few seconds to a few minutes and most symptoms disappear within 60 minutes. Some individuals may have a lingering feeling that something odd happened to the body. Dizziness, lack of coordination or poor balance are also symptoms related to TIA. Symptoms vary in severity