Upper Limb Inactivity Associated With Pain in Poststroke Complex Regional Pain Syndrome

Increased severity of upper limb inactivity was found to be associated with increased pain in patients experiencing poststroke complex regional pain syndrome (CRPS). These findings, from a cross-sectional study, were published in the Journal of Pain Research.

Patients (N=210) who had a first stroke between 2019 and 2020 were recruited for this study at Kishiwada Rehabilitation Hospital in Osaka, Japan. Differences in the 33-item Fugl-Meyer Assessment (FMA) of motor recovery after stroke, the 19-item Action Research Arm Test (ARAT), the Motor Activity Log (MAL), and the numerical rating scale (NRS) for pain were compared between patients with (n=19) and without (n=83) poststroke CRPS.

The mean ages of patients in the poststroke CRPS and control groups were 73.9±7.7 and 70.3±10.4 years, respectively; 31.5% and 45.7% were men, 63.2% and 56.6% had hemorrhage stroke, 31.5% and 51.0% had a right-sided lesion, the average time since stroke was 99.6±33.4 and 96.9±29.5 days, and Mini Mental State Examination (MMSE) scores were 25.9±1.3 and 26.4±2.5 points, respectively.

A large variation in functional outcomes was observed among the control group. However, on average, patients with poststroke CRPS were observed to have significantly lower FMA (mean, 10.1 vs 34.4; P <.001), ARAT (mean, 3.8 vs 24.8; P <.001), MAL assessing how much they used the affected upper limb (mean, 0.12 vs 2.56; P <.001), and MAL assessing how well they used the affected limb (mean, 0.06 vs 2.36; P <.001) scores compared individuals in the control group, respectively.

Among patients with poststroke CRPS, NRS scores were negatively correlated with upper limb FMA (r, -0.743; P <.01) and ARAT (r, -0.558; P <.01) scores. No correlations were observed between NRS and MAL amount of use (r, -0.416; P =.073) or quality of movement (r, -0.16; P =.502) scores.

A major limitation of this study is its small sample size of patients with CRPS.

These data indicate that the level of upper limb inactivity was found to be severely decreased among patients with poststroke CRPS compared with patients who did not develop CRPS. The study authors conclude, “[A] greater degree of inactivity was associated with higher pain intensity, suggesting that upper limb inactivity might influence poststroke CRPS.”