Friday, December 14, 2012

TERM: Transient ischemic attack (TIA)

Transient ischemic attack (TIA): A neurological event with the signs and symptoms of a stroke, but which go away within a short period of time. Also called a mini-stroke, a TIA is due to a temporary lack of adequate blood and oxygen (ischemia) to the brain - either in the brain, spinal cord or eye – without acute infarction (tissue death). This is often caused by the narrowing of the carotid arteries (the major arteries in the neck that supply blood to the brain).

CT scan slice of the brain showing a right-hemispheric ischemic stroke (left side of image).
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, aphasia, slurred speech and mental confusion.

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 plaque in one of the carotid arteries (i.e. two of the four major arteries supplying the brain) or from a thrombus (i.e. a blood clot) in the heart. In a TIA, the blockage period is very short-lived and 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.

TIAs typically last 2 to 30 minutes and can produce problems with vision, dizziness, weakness or trouble speaking.

If not treated, there is a high risk of having a major stroke in the near future. People who have a TIA have a 25% greater risk of having a stroke or other serious complication within 90 days.

Links:
Understanding Stroke Slideshow Pictures

Word List:
  • transient: continuing for only a short time
  • neurological: relating to nerves (for example, the brain)
  • adequate: enough in quantity, or good enough in quality
  • paralysis: a loss of control of, and sometimes feeling in, part or most of the body, caused by disease or an injury to the nerves
  • to dim: not enough light, not bright
  • aphasia: the loss of the ability to produce understandable speech (words pronounced correctly but not used correctly), because of brain damage
  • slurred = to pronounce words in a way that is not clear so that they run into each other, usually because you are drunk or tired
  • disfunction / dysfunction: the fact of a part of the body not working normally
  • mood: the way you are feeling at a particular time
  • cognition: the process by which knowledge and understanding is developed in the mind
  • embolus: a blood clot, air bubble, or small object that causes an blockage an artery in the body
  • to occlude: to cover or block something
  • to dislodge: to force or knock something out of its position
  • plaque: made from various substances that circulate in your blood and accumulates on the inner walls of your arteries
  • thrombus: A blood clot formed in situ within the vascular system of the body and impeding blood flow
  • lumen: central cavity of a tubular (for example a vein or artery) or other hollow structure in an organism or cell.

Pronunciation:
= transient
= neurological
= temporary
= adequate
= ischemia
= infarction
= carotid
= paralysis
= hemisphere
= aphasia
= slur
= dysfunction
= mood
= cognition
= embolus
= occlude
= dislodge
= plaque
= thrombus
= cholesterol
= lumen
= atherosclerotic
= dizziness
= complication

Reference:
Photo: Wikipedia by Lucien Monfils
MedicineNet.com: Transient ischemic attack
Wikipedia: Transient Ischemic Attack
WebMD.com: Arterial Plaque