Ministrokes
Ministrokes are usually caused by thrombosis, with clots forming in small sizes at different times from months to years apart. The death of nerve cells caused by each little infarct leads to a small degree of cognitive decline, including memory loss.
Typical Sequence of Symptoms
1. A sudden but small decline in mental faculties or slight weakness of an arm or leg.
2. Confusion and memory lapses that last a few days.
3. Gradual but incomplete recovery in mental faculties.
This sequence occurs because the brain reacts to the ministroke by pouring out edema fluid that compresses the area surrounding the dying brain tissue. As the edema subsides, the nerve cells that were compressed and paralyzed by the edema fluid regain their function, but those cells that already died in the center of the ministroke (infarct) cannot recover. Hence, there is only partial clinical recovery after each ministroke. If these little strokes occur repeatedly over several years, they can lead to full-blown dementia with severe memory loss. The history of repeated, staggered decline with incomplete cognitive recovery between episodes, together with clinical plus CT or MRI evidence of multiple strokes, help make the diagnosis.
Large Strokes
A large stroke is caused by blockage of a major blood vessel, most commonly the middle cerebral artery that supplies the regions of the brain controlling the motor and sensory systems, with loss of speech in the case of left-sided stroke. The middle cerebral artery supplies mainly the frontal and parietal lobes, and an area of the temporal lobe that does not include the hippocampus. Hence a large stroke causes only partial deficits in memory, primarily due to frontal lobe damage. These memory deficits can be difficult to assess in a patient with a paralytic stroke who has lost the ability to speak. Sometimes a large stroke can affect deeper parts of the brain, causing only partial paralysis, with
speech being preserved.
Strokes, whether large or small, are most commonly due to a thrombus, less frequently an embolus, and rarely hemorrhage. This priority list of likely causes is the driving force behind current preventive and therapeutic strategies.
Taken From: The Memory Program How to Prevent Memory Loss
and Enhance Memory Power
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