Practice of Integrated Volitional Control Electrical Stimulation in a Patient With Post-stroke Upper Limb Paresis and Difficulty in Thumb Opposition: A Case Report

Upper limb paresis after stroke often limits functional grasp and fine manipulation, particularly owing to impaired palmar abduction and opposition of the thumb. Integrated volitional control electrical stimulation (IVES) synchronizes voluntary muscle activity with electrical stimulation and may promote motor learning and cortical reorganization. However, most applications have focused on facilitating finger extension, and approaches specifically targeting active thumb movement remain limited. This case report describes an IVES-based intervention designed to promote thumb palmar abduction during voluntary finger extension. A 40-year-old right-handed man presenting with left hemiplegia underwent outpatient occupational therapy using IVES in power-assist mode. Electrodes were placed over the extensor digitorum communis and thenar muscles to induce synchronized finger extension and thumb palmar abduction. Task-oriented training simulating motorcycle maintenance tasks was performed for 60 min, three times per week, for 10 weeks. After the intervention, upper limb motor function and activity level outcomes improved. The Fugl Meyer Assessment Upper Extremity score increased from 37 to 47 points, the Simple Test for Evaluating Hand Function score increased from 11 to 30 points, and the grip strength of the affected hand increased from 0.5 to 6.0 kg. Additionally, Motor Activity Log scores improved, and the patient reported clinically meaningful gains in bimanual motorcycle maintenance performance on the Canadian Occupational Performance Measure. This case suggests that synchronizing thumb palmar abduction with voluntary finger extension using IVES may facilitate active motor learning and functional recovery of grasp patterns requiring thumb opposition, offering an active alternative to passive assistance approaches.