Correlation Between H-Reflex Excitability and Functional Motor Recovery in Chronic Stroke Survivors - A Cross-Sectional Observational Study

Background: Stroke is a leading cause of long-term disability, often resulting in sensorimotor deficits and impaired mobility. Understanding neurophysiological mechanisms such as spinal excitability and their role in motor recovery is critical for optimizing rehabilitation strategies. The Hoffmann reflex (H-reflex), a marker of spinal motor neuron excitability, has shown potential for assessing recovery following stroke. Objective: This study aimed to investigate the correlation between H-reflex excitability and functional motor recovery in chronic stroke survivors, focusing on the Hmax/Mmax ratio, latency, and amplitude of the H-reflex. Additionally, differences based on stroke type, hemiparesis side, and Brunnstrom recovery stages were explored. Methods: A cross-sectional observational design was employed, involving 30 chronic stroke survivors. H-reflex parameters were recorded for affected and unaffected limbs using posterior tibial nerve stimulation. Motor recovery was assessed using the Fugl-Meyer Assessment (FMA) and spasticity graded with the Modified Ashworth Scale (MAS). Pearson's correlation, independent samples t-tests, one-way ANOVA, and multiple linear regression were performed to analyze relationships between H-reflex measures and motor outcomes. Results: Hmax/Mmax ratio demonstrated a moderate positive correlation with FMA total motor scores (r = 0.48, p = 0.02), while latency showed a moderate negative correlation (r = -0.35, p = 0.04). Significant differences were observed in H-reflex parameters across stroke types (t(28) = 2.45, p = 0.02, Cohen’s d = 0.89) and Brunnstrom recovery stages (F (2, 27) = 4.32, p = 0.02, η² = 0.24). Multiple regression analysis revealed that Hmax/Mmax ratio (β = 0.42, p = 0.01) and latency (β = -0.28, p = 0.04) significantly predicted motor recovery, accounting for 52% of the variance (R² = 0.52). Conclusion: This study highlights the relevance of H-reflex parameters as neurophysiological markers for motor recovery in chronic stroke survivors. Findings underscore their utility in tailoring rehabilitation interventions and improving clinical outcomes. Further longitudinal studies are warranted to explore dynamic changes in spinal excitability and their impact on functional recovery. Key words: Chronic stroke survivors, Hoffmann reflex (H-reflex), Hmax/Mmax ratio, Functional motor recovery, Cross-sectional observational study