Reduced Modulations in Leg Muscle Activity During a Challenging Balance Task in Stroke Survivors



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Nearly 50% of stroke survivors experience a fall within 6-12 months after discharge from the hospital, which leads to significant complications and financial burdens on society. Balance control is an important factor contributing to falls in stroke patients. Therefore, it is important to understand the mechanisms underlying impaired balance control following a stroke. Remarkably, the contribution of cortical reorganization following stroke to impaired control of lower extremity muscles remains unknown. In this study, we investigated the modulation in leg muscle activity during a challenging balance task in stroke patients. We recruited 11 stroke patients with mild-to-moderate severity and 7 age-gender-matched healthy adults. Clinical assessment was performed using Berg Balance Scale and Time Up and Go tests. Participants were instructed to maintain balance in response to balance perturbations with varying difficulty levels (low, medium, and high) on a computerized balance platform with simultaneous neuroimaging using electroencephalography. The activity within the lower leg and thigh muscles on the non-affected side increased with the increase in balance task difficulty. However, such modulation was not observed on the affected side. Ongoing work is investigating the association between the brain and muscle activity and how it changes with the level of task difficulty in stroke patients. The reduced ability to modulate lower extremity muscle activity when an upright stance is challenged may contribute to poor balance control leading to a fall in stroke patients.