Background and aims: Pain associated with increased muscle stiffness is a common impairment after stroke. There is conflicting evidence about the differences in pressure pain threshold (PPT) and muscle stiffness between sides, i.e., affected vs. none-affected. Further, differences in PPT and muscle stiffness measured from the muscle belly (MB) and musculotendinous (MT) sites have been scarcely investigated in this population. This study aimed to compare pressure pain sensitivity and muscle stiffness maps of the gastrocnemius muscles in stroke survivors and matched healthy controls.
Methods: Ten first-stroke survivors and 10 age- and sex-matched controls were recruited. Pressure pain thresholds and muscle stiffness were measured bilaterally using a 12-point shaped grid covering MT and MB sites of the gastrocnemius muscles. A three-way analysis of variance (ANOVA) evaluated the differences in PPTs and stiffness, with sites and sides as the within-subject factors, and group as the between-subject factor.
Results: For PPT levels, the ANOVA detected significant differences between groups (F=14.919; p<0.001), but not between sites (F=1.374; p=0.182), and sides (F=0.798; p=0.372). For muscle stiffness, there were significant differences between sites (F=226.142; p<0.001), but not between groups (F=2.727; p=0.099), and sides (F=1.984; p=0.160). The post-hoc comparisons revealed higher PPTs in stroke survivors compared with controls, and increased stiffness in MT sites compared with MB sites.
Conclusions: These findings suggest decreased pressure pain sensitivity in the gastrocnemius muscles of stroke patients compared with controls, and no differences between sides in spatial distribution of gastrocnemius muscles stiffness in stroke survivors, and between stroke survivors and controls.

PRESSURE PAIN SENSITIVITY AND MUSCLE STIFFNESS MAPS OF THE GASTROCNEMIUS MUSCLES IN STROKE PATIENTS: A PILOT STUDY