慢性上肢痛を有する脳卒中生存者における経皮的耳介神経刺激による疼痛知覚の調節：無作為化、シャム対照パイロットスタディ

Chronic pain is a common and debilitating consequence of stroke. Although pharmacologic interventions are typically the first-line treatment, they often have limited efficacy and carry risks such as side effects and dependence. Evidence for neuromodulation therapies is positive but limited owing to high cost and invasiveness. Therefore, developing noninvasive, affordable neuromodulation approaches for treating poststroke pain could offer significant clinical benefits. Transcutaneous auricular neurostimulation (tAN), an affordable and wearable neuromodulation technique, has shown promise for analgesia, but research specific to poststroke pain remains limited.

This pilot study aims to explore the safety/feasibility, in addition to the analgesic effects, of tAN in patients with stroke with chronic upper-extremity pain.

Overall, 15 patients with stroke with chronic upper-extremity pain were enrolled. Each participant received a single 30-minute session of tAN (active or sham). Subjective stroke-related pain ratings and thermal pain thresholds (through quantitative sensory testing; QST) were collected immediately before and after the 30-minute tAN session. Repeated-measures two-way analyses of variance were performed with group (sham vs active tAN) and time (pre- vs post-tAN) as factors to evaluate the potential analgesic effects of tAN on both pain measures.

QST pain threshold analysis in the 14 patients who completed the study revealed a significant time × group interaction [F(1,12) = 7.658, p = 0.017]. Post hoc analysis indicated a potentiation in pain threshold after active stimulation (p = 0.032), whereas no change was observed in the sham group.

This pilot study showed that tAN is safe and feasible for patients with chronic poststroke pain. Although subjective pain scores improved in both groups, pain threshold increased significantly in the active group compared with the sham. Future studies should aim to assess long-term efficacy and optimized parameters, dosing, and treatment duration of tAN for this clinical population to aid in poststroke pain.

The Clinicaltrials.gov registration number for the study is NCT06456385.