Posted By CCF MD mdf on August 26, 1998 at 09:36:07:
In Reply to: mini-strokes posted by doug brown on August 26, 1998 at 08:02:16:
My Father, who has had extremely low blood pressure all his life, was just admitted to the hospital suffering from mini-strokes and high blood pressure. I'm especially interested in learning what mini-strokes are. Any information would be greatly appreciated.
As you'll see in the explanation below, "mini-strokes" is one of my least favorite terms because it is vague and can be used to describe two entirely different things.
One use of "mini-stroke" is as a synonym for TIA. Transient ischemic attacks (TIA) result when a blood vessel (feeding part of the brain) is blocked briefly, then blood flow is restored. By definition, symptoms from a TIA must last 24 hours or less, or else the event is called a stroke. Usually, TIAs are much shorter, lasting only minutes. If you take a picture with a CT or MRI at least a day later, you'll see no lasting effects of the transient loss of blood flow. That is, there is no damage to the brain by imaging, though some neurologists argue that it's hard to escape even just a little damage. In practical terms, though, a TIA is a stroke that didn't leave permanent damage.
Another use of "mini-stroke" is as a synonym for a lacunar infarct. This is not short-duration. Rather, it is a tiny area of the brain which is affected. Think of all the arteries that can feed parts of the brain. As they branch off the main supplying vessels (the carotids, for example), the branches become smaller and smaller. Block a relatively large vessel and you knock out a relatively large territory of brain, and severity of symptoms usually corresponds. The smallest arteries are about the size of a mechanical pencil tip - about half a millimeter. There are a lot of these arteries especially in the core region of the brain (you'll hear terms such as basal ganglia, thalamus, internal capsule). Knock out one of these vessels and you get a BB- or pea-size stroke. These may or may not produce symptoms, depending on the strategic location of the brain tissue damaged. In fact, we run into quite a few patients who have had several of these and never knew it, just because of chance.
The use of "mini-stroke" is probably reasonable for lacunar strokes. That is, the size of the stroke is truly small. The term "microvascular disease" is also a synonym, in case you run across it in connection with your dad. One of the major risk factors for microvascular disease is uncontrolled hypertension, so this may indeed be what your doctors are talking about.
The problem with that term for TIA is that a TIA could potentially affect a huge territory of brain, even though it doesn't last very long. TIAs are better explained to the lay public as "stroke warning signs."
I hope this information is helpful. CCF MD mdf.