Stroke on left side of brain
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Summary
5 papers analyzed
These studies suggest that left-sided strokes show differences in brain activity related to micturition, may be more severe but potentially mitigated by vagal nerve activity, and are more frequently recognized than right-sided strokes.
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Stroke on Left Side of Brain: Clinical Insights and Outcomes
Functional Brain Activity and Micturition Control
Research has shown that stroke laterality significantly impacts brain activity related to micturition. Specifically, left-sided strokes result in decreased brain activity in the left cerebellar anterior lobe and right limbic lobe (posterior cingulate) compared to right-sided strokes. This difference underscores the inherent functional disparities between the brain hemispheres, particularly in regions associated with lower urinary tract (LUT) control.
Infarct Location and Functional Outcomes
The location of the infarct in the brain plays a crucial role in determining the functional outcomes post-stroke. For left-sided strokes, preservation of the caudate nucleus, internal capsule, and cortical M5 region are strong predictors of a good functional outcome at three months. This contrasts with right-sided strokes, where the cortical M3 and M6 regions are more critical. These findings highlight the specialization of the dominant (left) hemisphere for language and the non-dominant (right) hemisphere for attention.
Stroke Severity and Vagal Nerve Activity
Patients with left-sided strokes tend to have more severe strokes, as indicated by higher NIHSS scores, compared to those with right-sided strokes. However, this severity can be moderated by the patient's vagal nerve activity, measured through heart-rate variability (HRV). High HRV appears to mitigate the severity differences between left and right-sided strokes, suggesting that adequate vagal nerve activity offers a protective effect.
Recognition and Frequency of Left-Sided Strokes
Left-sided strokes are more frequently recognized and diagnosed compared to right-sided strokes. This discrepancy is evident in clinical settings where ischemic strokes and transient ischemic attacks (TIAs) are more often identified on the left side. However, MRI scans do not show a significant difference in the distribution of infarcts between the left and right hemispheres. This suggests that left-sided strokes are more easily recognized, potentially leading to a bias in clinical diagnosis.
Anosognosia for Hemiparesis
Anosognosia for hemiparesis (AHP), a condition where patients are unaware of their paralysis, is rare in left-sided stroke patients. This rarity might be due to the overlap of language dysfunction, which complicates the assessment of self-awareness. In a study of 44 acute left-sided stroke patients, only one exhibited AHP, and this patient showed a reversed lateralization of language functions. This finding argues against a primary role of the left hemisphere in self-awareness of limb function.
Conclusion
Left-sided strokes present unique challenges and outcomes compared to right-sided strokes. Differences in brain activity, functional outcomes, stroke severity, and recognition highlight the specialized roles of the brain's hemispheres. Understanding these distinctions is crucial for improving diagnosis, treatment, and rehabilitation strategies for stroke patients.
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