Some Electrical Stimulation Inventions May Decrease Pain Intensity in TMD

Transcutaneous electrical nerve stimulation (TENS) and high-voltage current treatments may be viable interventions for reducing temporomandibular disorder (TMD) pain, according to a systematic review and meta-analysis published in The Journal of Pain.

Investigators from Universidad de Castilla-La Mancha in Spain searched publication databases through March 7, 2022, for randomized clinical trials of electrical stimulation interventions for the treatment of TMD-associated pain.

A total of 7 studies that included 189 patients with TMD were selected for the analysis. The active interventions included TENS (n=5), high-voltage stimulation (n=1), and contingent electrical stimulation (CES) administered at a wide variety of frequencies, current intensities, and durations. The comparator groups were either control or sham treatment.

The primary outcome in 6 studies was pain intensity measured using the Visual Analogue Scale and numerical pain rating scales and 4 of the studies included a follow-up lasting between 24 hours and 1 month.

The patients had a mean age of 27 years and 71% were women.

In the pooled analysis, pain was reduced in patients who received electrical stimulation compared with control (mean difference [MD], -1.12; 95% CI, -1.49 to -0.76 cm; I², 57%). A subgroup analysis found no significant difference between modalities (c², 0.92; P =.63), however, the greatest effect was observed for TENS and no effect was observed for CES.

The electrical stimulation interventions did not appear to have a significant effect on range of motion (MD, 0.97; 95% CI, -0.27 to 2.2 mm; I², 68%; P =.12) or muscle activity (standardized MD, -2.91; 95% CI, -8.13 to 2.31; I², 97%; P =.27). The observed effects on muscle activity were significantly different between TENS and CES interventions (c², 35.3; P <.001).

The limitations of this analysis included methodological biases and the risk of bias for blinding of personnel. Additionally, the analysis was limited by the heterogeneity of the applied programs and the lack of data values on current density.

 “TENS and high-voltage current stimulation reduces pain intensity clinically in people with temporomandibular disorders with a moderate quality of evidence,” the researchers noted. “On the other hand, there is no evidence of the effect of different electrical stimulation modalities on range of movement and muscle activity in people with temporomandibular disorders with a moderate and low quality of evidence respectively,” they added.