What you should know
What is a stroke?
A stroke or brain attack occurs when a blood clot blocks a blood vessel or when a blood vessel breaks, interrupting blood flow to an area of the brain. When a brain attack occurs, it kills brain cells in the immediate area. Doctors call this area of dead cells an infarct. These cells usually die within minutes to a few hours after the stroke starts.
When brain cells die, they release chemicals that set off a chain reaction called the "ischemic cascade." This chain reaction endangers brain cells in a larger, surrounding area of brain tissue for which the blood supply is compromised but not completely cut off. Without prompt medical treatment this larger area of brain cells, called the penumbra, will also die. Given the rapid pace of the ischemic cascade, the “window of opportunity” for interventional treatment is about three to six hours. Beyond this window, reestablishment of blood flow and administration of neuroprotective agents may fail to help and can potentially cause further damage. The most important thing to remember is that the earlier a stroke victim gets to the emergency department, the better the chance that they will be able to receive treatment that stops or reduces the amount of brain damage from the stroke.
When brain cells die, functions previously under control of the dying brain are lost. These include functions such as speech, movement, and sensation. The specific abilities lost or affected depend on where in the brain the stroke occurs and on the size of the stroke. For example, someone who has a small stroke may experience only minor effects such as weakness of an arm or leg. On the other hand, someone who has a larger stroke may be left paralyzed on one side or lose his/her ability to express and process language. Some people recover completely from less serious strokes, while other individuals lose their lives to very severe strokes.
Time to Presentation
- 58% of stroke patients don't present until 24 hours or more after the onset — Alberts et al, 1990
- 13 hours is median time from stroke onset to presentation — Feldman et al, 1993
- 17% of adults over age 50 can't name a single stroke symptom — NSA/Gallup Survey, 1996
Importance of establishing time of onset of stroke
It is very important to establish the time of onset of stroke. If the time of onset cannot be reasonably established, the stroke victim is not a candidate for TPA, a “brain saving” drug that breaks apart the blood clots in the brain which are causing the stroke.
- Questions about symptom onset time
- Last time patient was seen completely normal?
- What was the patient doing?
- What were you (family member) doing?
- How do you know the time?