Transient Ischemic Attacks

A TIA is a warning of impending ischemic stroke

A transient ischemic attack or TIA is most usually a brief spell of numbness, weakness, or blindness that lasts less than 10 minutes. A TIA is an important indicator that the stage is set for an ischemic stroke, because it demonstrates that enough vascular and/or cardiac pathology is present to produce neurologic symptoms. It's the brain sounding an alarm. Tests are now available to identify the causes of many TIAs, and provide information on which to base specific medical or surgical treatment. These treatments help prevent stroke and save lives. We will discuss some of them in later modules.

During a TIA, an artery is temporarily blocked

TIAs are produced by transient blockage of the cerebral or retinal circulation. Embolization of thrombi formed on plaques in the extracranial portions of the carotid and vertebral arteries or of thrombi formed in the diseased heart are two important causes. In both cases, what seems to happen is this material travels into an artery and briefly plugs it up, but then, for some unknown reason, the thrombus breaks up and circulation through that part of the vessel is re-established. Little if any nervous tissue actually dies, and therefore the patient has no permanent neurologic deficit. It is unusual for hemorrhage into brain tissue to cause transient, specific neurological deficits because the signs/symptoms can be reversed only when the blood has been removed--a process that takes weeks or months, not a few minutes

Sometimes the symptoms produced by recurrent TIAs are exactly the same each time they occur. Other times the symptoms are different and can even occur on the other side of the body. Remember that a TIA occurs when an artery is temporarily blocked and a particular brain region (or the retina) therefore becomes ischemic. If the same region of one artery is being blocked each time, this would produce the same set of symptoms.

Question

How would you explain TIAs that produce different symptoms?

Answer

A different region of the same artery or another artery altogether is being blocked.

Mrs. C. had at least three TIAs over a 48-hour period.

Mrs. C: "TIA Description"

Meet the patient

If patients don't tell you about having a TIA, or if you fail to recognize that they are describing a TIA, you will miss an opportunity to intervene and perhaps prevent a stroke

For more information about TIAs:

More About a Transient Ischemic Attack

A series of repeated TIAs characterized by identical neurological deficits is often a warning sign that a major vessel contains an unstable plaque on which thrombi are repeatedly forming (and causing ischemia) and then fragmenting (and allowing blood to flow again). The neurological features of these TIAs are often indicative of the deficit, or part of the deficit, that would be produced by the impending "completed" stroke.

It is less likely that cardiac emboli will repeatedly produce the same deficits--they are able to travel to any part of the brain. In some individuals, TIAs may result from decreased perfusion of large arteries that are already partially occluded by plaque. This might occur with fluctuations in blood pressure produced by overzealous medication or by various cardiac arrhythmias.