Comparison of the reaction time of wrist flexion and extension between patients with stroke and age-matched healthy subjects and correlation with clinical measures

Abstract

Background Brain injury had an effect on reaction time (RT) and brain-injured patients were normally significantly slower than normal controls. The RT of the paretic upper limb (UL) in patients with stroke was slower than in a control group. The present study was designed to compare the RTs of the unaffected and affected sides in stroke survivors and those of normal subjects. This study also explores the relationships among wrist flexion and extension RTs in the affected side and the motor deficits of the UL as measured by clinical Composite Spasticity Index (CSI), Associated Reaction Rating Score (ARRS), and Wolf Motor Function Test (WMFT) scores. Methods Ninety-eight hemiparetic stroke survivors and 20 normal subjects participated in the study. Abnormal muscle tone was measured by CSI. Associated reaction was measured by ARRS. Motor function was measured by WMFT. The subject was asked to flex or extend the affected and non-affected wrists as fast as possible, following an auditory “go” signal. An electrogoniometer attached to the wrist measured wrist flexion and extension angle. RT was defined as the time from the “go” signal to a change in wrist angle denoting movement onset. Clinical assessments and RT were conducted within one day. Differences in the variables between normal subjects and the unaffected sides of the stroke patients were analyzed using analysis of variance. Correlations were assessed by computing Spearman's correlation coefficient. The significance level was set at 5%. Results RTs of wrist flexion and extension in the stroke survivors' affected hands were significantly longer than those in normal subjects and their unaffected hands (P <0.01 for both). The wrist flexion RT moderately correlated with CSI (ρ=0.412, P<0.001) and ARRS (ρ=0.341, P <0.001) and with WMFT functional ability (negatively; ρ=-0.531, P <0.001) and time score (ρ=0.504, P <0.001). Similarly, the wrist extension RT moderately correlated with CSI (ρ=0.429, P<0.001), ARRS (ρ=0.374, P<0.001), and with WMFT functional ability (negatively; ρ=−0.531, P <0.001) and time score (ρ=0.486, P <0.001). Conclusions RTs of wrist flexion and extension on the stroke survivors' affected sides were significantly longer than those on the unaffected sides and those of normal subjects. The wrist flexion and extension RTs moderately correlated with CSI and ARRS and inversely with motor functional performance of the UL in patients with stroke.