Although it’s commonly known that severe ischemic strokes can cause brain damage or even death, a new study reveals that smaller “mini strokes” can also have a serious impact on neurological function, according to Everyday Health. These mini strikes can lead to permanent damage and increase risk for a full-blown stroke. Since there aren’t warning signs for these silent strokes and MRIs generally are not sensitive enough to detect these injuries, mini strikes often go undiagnosed and may be key contributors to age-related cognitive decline and dementia.
Maiken Nedergaard, the lead author of the study and professor of neurosurgery at the University of Rochester Medical Center, used rodents to examine the impact of mini strokes, which are also known as microinfarcts. After injecting the mice with cholesterol crystals, which caused the small strokes, the researchers observed the mice during a series of tasks such as responding to audio cues and recalling objects.
Results showed that mice that suffered the strokes were more likely to fail these tasks. Researchers also discovered that microinfarcts can similarly progress with immediate cell death followed by the brain quickly sealing off the stroke site to “digest” the damaged tissue. However, some mini strokes caused cell death that dragged on for several weeks, which the researchers labeled “incomplete lesions.” Since the cell death isn’t immediate, as is the case in acute ischemic strokes, physicians could have more time to medically intervene and stop the neuronal death that often results.
Strokes are common in older adults and cause more than 140,000 deaths each year. Blood flow that is blocked to a small area of the brain causes strokes, but immediate symptoms, such as numbness, blurry vision, and slurred speech, are usually only present in acute ischemic strokes. Mini strokes usually pass without notice, and Nedergaard notes how “that’s the scary thing about them, you don’t know they’re occurring.”
A series of mini strokes could result in a prolonged period of damage to the brain, and studies have correlated the presence of mini strokes with dementia and age-related cognitive decline. About 55 percent of individuals who have been diagnosed with mild dementia show evidence of past mini strokes. However, Nedergaard notes how the findings can help to potentially save patients from permanent damage: “This observation suggests that the therapeutic window to protect cells after these tiny strokes may extend to days and weeks after the initial injury.”