From the Research
Approximately 0.17% of hemispheric stroke patients can have ipsilateral symptoms, as reported in the most recent and highest quality study available 1. This phenomenon contradicts the typical contralateral presentation where stroke symptoms appear on the opposite side of the body from the brain lesion. Ipsilateral symptoms can occur due to several mechanisms, including:
- Abnormal brain organization where motor pathways don't cross at the medullary pyramids as they typically do
- Uncrossed motor fibers that normally constitute a small percentage of the corticospinal tract
- Bilateral representation of certain functions in the brain leading to ipsilateral deficits
- Mass effect from large strokes causing compression of the opposite hemisphere or brainstem, resulting in ipsilateral symptoms Recognizing this possibility is crucial for accurate diagnosis and treatment planning, as clinicians might otherwise attribute symptoms to a different pathology if they strictly adhere to the expectation of contralateral deficits. The study by 1 found that ipsilateral hemiparesis was detected in 14 patients out of 8360, with a mean age of 71 years and a history of previous stroke contralateral to the recent lesions in 13 patients. Another study by 2 reported a series of six cases of acute ipsilateral weakness or numbness following a hemorrhagic or ischemic stroke, with involvement of the ipsilateral corona radiata, internal capsule, basal ganglia, insula, and thalamus in all cases. However, the study by 1 provides the most recent and highest quality evidence, and its findings should be prioritized in clinical decision-making. It is essential to consider the possibility of ipsilateral symptoms in stroke patients, as it can impact treatment planning and outcomes, and the most recent evidence suggests that approximately 0.17% of hemispheric stroke patients can experience ipsilateral symptoms 1.