Relationship between spinal reflexes and leg motor function in sub-acute and chronic stroke patients

Objective: To assess the relationship between spinal reflexes and motor function in sub-acute (SAS) and chronic stroke (CS) patients. Methods: Twelve SAS and 16 CS patients underwent electrophysiological assessment of heteronymous facilitation (HF), heteronymous inhibition (HI), disynaptic reciprocal inhibition (DRI), and D1 inhibition (D1). The Fugl-Meyer Assessment Lower Extremity (FMA-LE) and modified Ashworth scale (MAS) were assessed. The relationship between spinal reflexes and motor function was examined in a cross-sectional manner. SAS patients were also longitudinally evaluated before and after intensive rehabilitation for approximately 2 months. Results: SAS patients with triceps surae muscle spasticity (MAS ≥ 1) showed higher HF values (p = 0.03) than those without spasticity. SAS patients with quadriceps muscle spasticity showed higher HF values (p < 0.01); patients with hamstring muscle spasticity showed higher DRI value (disinhibition) (p < 0.01) than those without spasticity. CS patients showed no significant correlation between spinal reflexes and motor function. The longitudinal study revealed a significant correlation between increase in D1 inhibition and FMA-LE improvement in SAS patients (r = 0.69). Conclusions: The association between impaired spinal reflexes varies with the stage of stroke; HF and DRI may be spasticity indicators in SAS patients. Significance: Spinal reflexes as potential biomarkers may facilitate tailor-made rehabilitation of stroke patients.