Abstract: Objective To evaluate the relationship between the ratio of the maximal value of the H-reflex to the maximal value of the M response (Hmax/Mmax), the ratio of the developmental slope of the H-reflex to the slope of the M response (Hslp/Mslp), and the ratio of the threshold of the H-reflex to the threshold of the M response (Hth/Mth) and upper-extremity spasticity in stroke patients. Methods Upper-extremity spasticity in 34 stroke patients was assessed by modified Ashworth Scale (MAS). H-reflex was recorded in flexor carpi radialis muscle on both sides. Hmax/Mmax, Hslp/Mslp and Hth/Mth in the spastic side were compared to the unaffected side. Results The mean of Hmax/Mmax (spastic side, 0.36±0.17; unaffected side, 0.14±0.07) and Hslp/Mslp (spastic side, 0.72±0.40; unaffected side, 0.26±0.22) showed significant difference between 2 sides (P<0.05). The mean of Hth/Mth (spastic side, 0.93±0.14; unaffected side, 0.98±0.12) showed no significant difference (P>0.05). Hmax/Mmax and Hslp/Mslp were correlated positively with score of MAS in the stroke patients (r=0.608, P<0.05; r=0.917, P<0.05), while there was no correlation between Hth/Mth and score of MAS (r=-0.128, P>0.05). Conclusion Hmax/Mmax and Hslp/Mslp could be sensitive electrophysiologic parameters to evaluate upper-extremity spasticity after stroke.

Key words: stroke, spasticity, upper-extremity, H-reflex