Cardiac autonomic status is associated with spasticity in post-stroke patients

BACKGROUND: Whether post-stroke spasticity is associated with autonomic status is unclear. The purpose of our study was to determine whether spasticity in post-stroke patients is associated with heart rate variability (HRV), an indicator of sympathetic and parasympathetic regulation. OBJECTIVE: To determine whether HRV is associated with spasticity in post-stroke patients. METHODS: Our cross-sectional observational study included 21 post-stroke patients with varying degrees of knee spasticity. We measured patients' heart rate variability (HRV) during the morning and afternoon of the same day using the modified Ashworth assessment and the pendulum test. The relationship between HRV and the spasticity parameters was evaluated based on the Pearson correlation coefficient (r). RESULTS: The data for the morning measurements showed that the relaxation index negatively correlated with the high frequency (HF) power of HRV (r = -0.47, P <0.05), and positively correlated with the low frequency (LF) power of HRV (r = 0.47, P <0.05) and the LF/HF power ratio (r = 0.55, P <0.05). Similar correlations were observed between the diurnal differences of HRV and the relaxation index. No correlation was observed among the data for the afternoon measurements. CONCLUSIONS: Higher parasympathetic tone and lower sympathetic tone are associated with a higher degree of knee spasticity in post-stroke patients. Further studies are warranted to confirm our findings and investigate the pathological mechanisms involved.