Transcutaneous electrical nerve stimulation effects on pain-intensity and endogenous opioids levels among chronic low-back pain patients: A randomised controlled trial.

BACKGROUND

Transcutaneous electrical nerve stimulation (TENS) is a promising non-pharmacological modality for the management of chronic low back pain (CLBP), but its efficacy and mode of action have not been clearly established.

OBJECTIVE

To evaluate the responses of plasma beta-endorphin (βE), met-enkephalin (ME), and pain intensity (PI) among patients with CLBP exposed to TENS or sham-TENS.

METHODS

This double-blind trial involved 62 participants (aged 53.29 ± 5.07 years) randomised into TENS group (frequency 100 Hz, burst-rate 2 Hz, burst-width 150 μs, intensity 40 mA, duration 30 min), and sham-TENS group. The PI and plasma concentrations of βE and ME were measured at baseline, immediately (0 hr), 1 hr, 24 hrs, and 48 hrs post-intervention. Data were analysed using general linear model repeated measures, ordinal regression, one-way analysis of variance, Kruskal-Wallis test, independent and paired samples t-tests, Mann-Whitney U test, Wilcoxon signed-rank test, and Kendall's tau coefficient.

RESULTS

There was a significant temporal difference in PI between groups, F (1, 58) = 18.83, p< 0.001; the TENS group had better pain relief. The relative analgesic effect of TENS started immediately after the intervention (median difference [M⁢D] =-3, p< 0.001), peaked at 1 hr (M⁢D=-4, p< 0.001), and worn out by 24 hrs (M⁢D=-1, p= 0.029). However, there was no significant difference in βE and ME between the groups from 0 hr to 24 hrs post interventions, and no significant correlation between the PI, and βE, or ME.

CONCLUSION

TENS significantly reduced PI up to 24 hrs after treatment.