The effects of photobiomodulation and transcutaneous electrical nerve stimulation on chronic neck pain: A double-blind, randomized, sham-controlled trial

BACKGROUND: Photobiomodulation (PBM) and transcutaneous electrical nerve stimulation (TENS) are used to reduce neck pain.

OBJECTIVE: To investigate the immediate and 1-month post-treatment effects of 10 treatment sessions of PBM and TENS delivered over 2 weeks on pain intensity in individuals with neck pain.

METHODS: Individuals with neck pain were randomized into four groups: PBM+TENS, PBM, TENS, and Sham.

PRIMARY OUTCOME: pain intensity at rest.

SECONDARY OUTCOMES: pain intensity during movement, pressure pain threshold (PPT), temporal summation (TS), conditioned pain modulation (CPM), cervical range of motion (ROM), psychosocial factors, drug intake for neck pain, and global perceived effect (GPE). All outcome assessments were made pre- and post-treatment. Mean differences and 95 % confidence intervals were calculated for between-group comparisons.

RESULTS: A total of 144 participants were recruited. No significant between-group difference was observed for pain intensity at rest, TS, CPM, ROM, psychosocial factors, and drug intake. The PBM+TENS showed a reduction in pain intensity during movement and GPE compared to the PBM (MD: 1.0 points; 95 % CI: 0.0, 2.0; MD: 2.0 points; 95 % CI: 1.0, 3.0) and Sham (MD: 2.0 points; 95 % CI: 1.0, 3.0; MD: 2.0 points; 95 % CI: 1.0, 3.0) groups. PBM+TENS presented a medium effect size to increase local PPT compared to PBM and Sham groups. TENS presented a medium effect size to increase local PPT compared to PBM and Sham groups. TENS presented a medium effect size to increase distant PPT compared to other groups.

CONCLUSIONS: The use of PBM or TENS was not effective for reducing pain intensity at rest. The combination of PBM and TENS was effective in improving pain intensity during movement, local hyperalgesia, and the GPE. TENS reduced local and distant hyperalgesia.