Investigation into the Effectiveness of Combining Transcranial Direct Current Stimulation and Transcutaneous Electrical Nerve Stimulation as Treatment Options for Poststroke Shoulder Pain by Utilizing Functional Near-Infrared Spectroscopy.

Objective: The aim of this study is to explore the therapeutic effects of transcranial direct current stimulation (tDCS) and transcutaneous electrical nerve stimulation (TENS) on post stroke shoulder pain (PSSP).

Methods: We enrolled 13 individuals in this study who underwent three different treatments in a random sequence: active tDCS+active TENS, active tDCS+sham TENS, and sham tDCS+active TENS. Each treatment was administered once, with a 3-day washout period between interventions. A blinded rater assessed the visual analog scale (VAS) scores, fNIRS readings, and sensory and pain tolerance thresholds of the participants before and after the stimulation.

Results: All three treatment methods can significantly alleviate PSSP (p<0.05). Compared with using tDCS alone, tDCS+TENS can significantly improve pain, with a statistically significant difference (p<0.05). In the 2KHz PTT task, the three treatment methods showed significant differences (p<0.05) in the mean oxygenated hemoglobin (HbO) levels in the false premotor cortex (PMC)/auxiliary motor area (SMA) before and after intervention.

Conclusion: The combination of tDCS+TENS can increase the pain-relieving impact on PSSP when compared to using tDCS alone. TENS may contribute an additional effect on the inhibitory systems influenced by tDCS that help reduce pain.

Clinical Registration Number: Registration website: https://www.chictr.org.cn. Registration date: 2022-02-25. Registration number: ChiCTR2200056970.