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

Abstract

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.

Keywords:

• functional near-infrared spectroscopy
• pain tolerance threshold
• post-stroke shoulder pain
• transcranial direct current stimulation
• transcutaneous electrical nerve stimulation

Abbreviations

PSSP, post stroke shoulder pain; TENS, transcutaneous electrical nerve stimulation; tDCS, transcranial direct current stimulation; fNIRS, functional near-infrared spectroscopy; CRPS, complex regional pain syndrome; CPSP, central poststroke pain; CPT, current perception thresholds; PTT, pain tolerance threshold; VAS, visual analogue scale; SAC, the somatosensory association cortex; SMC, the somatosensory cortex; M1, the primary motor cortex; PMC, the premotor cortex; SMA, the supplementary motor area; PFC, the prefrontal cortex; HbR, deoxygenated hemoglobin; HbO, oxygenated hemoglobin; IHI, interhemispheral inhibition.

Data Sharing Statement

The datasets used and analysed during the current study available from the corresponding author on reasonable request.

Ethics Approval and Consent to Participate

This study was conducted in accordance with the declaration of Helsinki. This study protocol was approved by the ethics committee of the first affiliated hospital of Fujian Medical University, No: MRCTA, ECFAH of FMU [2020] 269. A written informed consent was obtained from all participants.

Consent for Publication

Consent for publication was obtained from every individual whose data are included in this manuscript.

Acknowledgments

The authors wish to thank all participants for their willingness and help. We would like to thank the reviewers for their constructive criticism and suggestions.

Disclosure

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Additional information

Funding

This work was supported by the StartupFund for scientific research, Fujian Medical University (2019QH1086, Fuzhou) to Y Li.