Five-digit sensory-motor hand assessment post stroke

Stroke induces profound changes in the sensory-motor performance of the human hand, an organ with intricate multi-digit interactions. Recognizing the clinical need for precise assessment of hand performance post-stroke, we have developed a five-digit robotic system capable of precisely assessing both individual digit function and the complex inter-digit passive and active couplings. The 5×5 passive stiffness matrix, loss of individuation in active movement, and proprioception matrix across 5 digits were characterized through a systematic approach, thereby enabling accurate assessment of sensory and motor impairments. Comparative analyses between stroke survivors and healthy controls reveal significant deficits in hand motor and sensory performance post stroke, including excessive inter-digit coupling, markedly reduced individuation, particularly in the ulnar digits, and compromised proprioception during flexion. The study provides us with the unique capability to capture both local and coupled properties of hand function, potentially helping us develop impairment-specific rehabilitative interventions.