Disruption of Interlimb Sensorimotor Synchronization After Stroke: Physiological Mechanisms, Physical Examination Innovation, And Global Physiotherapy Intervention Models

Abstract Background: Current stroke rehabilitation treats limbs largely independently, despite mounting evidence that bilateral sensorimotor synchronization—the coordinated temporal and spatial control of bilateral limb movement—represents a core physiological requirement for functional recovery. No standardized physiotherapy assessment quantifies interlimb phase lag, bilateral proprioceptive integration, or force-sharing asymmetry as measurable physiological impairments. Objectives: To characterize physiological mechanisms underlying interlimb sensorimotor synchronization disruption after stroke, establish a novel physical examination framework measuring temporal motor output mismatch and bilateral proprioceptive integration, and evaluate physiotherapy strategies restoring synchrony beyond unilateral strength focus. Methods: Systematic integration of evidence from gait biomechanics, neurophysiology (central pattern generators, interhemispheric coupling), proprioceptive assessment, and bilateral movement training literature in post-stroke populations. Novel assessment framework developed incorporating: interlimb phase lag measurement, bilateral proprioceptive accuracy, force-timing asymmetry quantification, postural stability under asymmetrical sensory input, and neural timing consistency. Key Findings: Post-stroke interlimb sensorimotor synchronization disruption manifests through: (1) increased interlimb phase lag during walking (normal 0°, post-stroke 23.4±8.2°) and pedaling (normal 180° coordination, post-stroke 152.1±16.4°); (2) bilateral proprioceptive asymmetry with distal dominance (wrist 3.2-fold greater deficit than shoulder); (3) force-sharing asymmetry independent of strength (work asymmetry r=0.78 with phase coordination, r=0.32 with motor impairment); (4) proprioceptive-motor coupling loss correlating with coordination deficits (r=0.71); (5) postural instability under contralateral sensory perturbation indicating bilateral proprioceptive integration failure. Integrated assessment framework correlates with Fugl-Meyer (r=0.76) and functional walking ability (r=0.82). Clinical Implications: Physiotherapy assessment and intervention should explicitly target interlimb synchronization restoration through central pattern generator stimulation, bilateral proprioceptive integration training, and force-coupling retraining—applicable across acute-to-chronic phases and high-to-low resource settings without pharmacological or surgical dependence. Conclusions: Interlimb sensorimotor synchronization disruption represents a distinct, measurable post-stroke pathophysiology independent from unilateral strength deficits. Establishing standardized physiotherapy assessment operationalizes this construct clinically, enabling mechanism-informed rehabilitation that restores coordinated bilateral movement through spinal and supraspinal motor network reorganization. Stroke; Interlimb Coordination; Bilateral Synchronization; Proprioception; Central Pattern Generators; Gait Asymmetry; Sensorimotor Integration; Physiotherapy Assessment; Motor Recovery; Rehabilitation Mechanism