What side does a stroke affect
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The Impact of Stroke on Affected Side: Insights from Recent Research
Introduction to Stroke and Affected Side
A stroke occurs when the blood supply to part of the brain is interrupted or reduced, preventing brain tissue from getting oxygen and nutrients. This can lead to the impairment of motor and sensory functions, typically on the side of the body opposite to the brain lesion. Understanding which side of the body is affected by a stroke and how it impacts recovery is crucial for effective rehabilitation.
Ipsilesional Hand Function and Brain Lesion Side
Research indicates that the side of the brain lesion significantly affects the ipsilesional hand function in stroke survivors. A study assessing hand function through various tests found that while maximum strength in the ipsilesional hand is preserved, dexterity is notably impaired, especially in individuals with right brain lesions. This suggests that the right hemisphere plays a critical role in fine motor skills.
Motor Cortex Organization and Recovery
The organization of the motor cortex post-stroke is influenced by the side of the stroke and the level of recovery. Functional MRI studies reveal that patients with right arm involvement show smaller activation in the contralateral motor cortex compared to those with left arm involvement. Additionally, those with full recovery exhibit significantly larger contralateral sensorimotor cortex activation. This highlights the importance of targeted rehabilitation strategies based on the side of the stroke.
Ipsilateral Sensory-Motor Deficits
Early after a stroke, sensory-motor deficits can occur on the ipsilateral side, particularly on the right side. This is evident from performance tests comparing stroke patients to healthy volunteers, where the right ipsilateral side showed significantly worse performance. This finding underscores the need for comprehensive assessment and rehabilitation that includes the ipsilateral side.
Motor Training and Less-Affected Side
Motor training involving the less-affected side (MTLA) has shown promising results in improving both the less-affected and affected sides in post-stroke patients. A randomized controlled trial demonstrated significant improvements in muscle strength, dexterity, and coordination on the less-affected side, as well as enhanced motor recovery on the affected side. This suggests that MTLA can be an effective component of stroke rehabilitation.
Functional Recovery and Side of Weakness
The side of weakness (hemiplegia) post-stroke can influence the duration and outcome of rehabilitation. Patients with right hemiplegia often require longer rehabilitation but may show better functional recovery in activities of daily living (ADL) at discharge. However, the side of weakness does not significantly affect overall functional recovery when measured at set times post-stroke. This indicates that while the side of weakness may influence the rehabilitation process, it does not necessarily determine the final outcome.
Motor Excitability and Action Observation
Stroke patients exhibit increased motor excitability during action observation, with significant differences between the affected and non-affected sides. This increase is more pronounced when observing actions performed by the same hand as the one viewed in the video. These findings support the potential use of action observation as a therapeutic strategy in stroke rehabilitation.
Weight Shifting and Balance Improvement
Exercises involving weight shifting to the nonparetic side on an inclined surface can improve standing balance in the early phase after a stroke. Such exercises have been shown to enhance lateral weight-shifting capacity and gait ability, suggesting their incorporation into early rehabilitation programs.
Locomotion and Sensorimotor Interactions
During locomotion, post-stroke subjects exhibit stronger electromyography responses on both sides when the tibial nerve of the unaffected leg is stimulated. This indicates impaired processing of afferent input from the affected leg and highlights the strong mutual influences between the unaffected and affected sides during movement. These interactions can be leveraged to optimize rehabilitation approaches.
Immune Response and Sympathetic Dysfunction
Stroke can lateralize immune responses, with significant differences in T-lymphocyte reactivity between the paretic and non-paretic sides. This lateralization is influenced by the localization of the brain lesion, the clinical course of the disease, and the presence of motor deficits. Understanding these immune responses can inform post-stroke care and rehabilitation strategies.
Conclusion
The side of the brain lesion in stroke patients significantly impacts motor and sensory functions, recovery processes, and rehabilitation outcomes. Comprehensive assessment and targeted rehabilitation strategies that consider the side of the stroke can enhance recovery and improve the quality of life for stroke survivors.
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