Effects of noxious thermal stimulation on lower-limb motor function in chronic stroke: a randomized controlled trial with 1-month follow-up.

BACKGROUND

Thermal stimulation (TS) is a practicable, inexpensive, and convenient treatment method in stroke rehabilitation. Previous studies have already confirmed that alternate noxious TS can enhance cortical excitability in patients who had a stroke, thereby improving the motor function of the affected limbs. However, it remains unclear whether continuous noxious TS (either hot-only or cold-only) or alternative noxious TS produces comparable therapeutic effects in chronic stroke, and whether such effects will persist up to one month after the immediate post-intervention phase.

PURPOSE: To quantify the immediate and short-term effects of noxious cold only, noxious heat only, and alternate noxious TS on the motor function of the lower extremity (LE) in patients with chronic stroke.

METHODS

Thirty-seven patients with first-ever stroke after six months participated in this prospective, assessor-blind, randomized controlled trial. Participants were randomly assigned to one of three groups for three-week TS intervention, while maintaining their regular stroke rehabilitation. The alternate group underwent both noxious heat and cold TS (heat-pain46-47°C/cold-pain 2-3°C), the noxious heat group underwent heat-pain TS, and the noxious cold group underwent cold-pain TS. The LE subscale of the Fugl-Meyer assessment, Timed Up and Go (TUG) test, Barthel index, and Hmax/Mmax ratio were measured at pre-intervention, post-intervention, and 1-month follow-ups. Data were analyzed using linear mixed-effects models under the intention-to-treat principle.

RESULTS

The Group by Time interaction was significant only for the TUG (p = .041, ηp2 = 0.16). Significant within-group improvements in TUG performance were observed in both the alternate TS (p = .004, ηp2 = 0.44) and noxious-cold TS groups (p = .003, ηp2 = 0.49). Post-hoc simple-effect analysis showed that the noxious-cold group demonstrated significantly shorter TUG times at both post-intervention and follow-up compared with baseline (p = .036 and <0.001, respectively). In contrast, pairwise comparisons in the alternate TS group were not statistically significant after correction (p > .05). No significant changes were found in the FMA-LE, BI, or Hmax/Mmax (p > .05).

CONCLUSIONS

Combining noxious-cold or alternate noxious TS interventions with regular rehabilitation may lead to better LE mobility in patients with chronic stroke.

TRIAL REGISTRATION: ClinicalTrials.gov NCT04306120.