Effects of burst-type transcutaneous electrical nerve stimulation on cervical range of motion and latent myofascial trigger point pain sensitivity

Abstract

Objective: To assess the effects of a burst application of transcutaneous electrical nerve stimulation (TENS) on cervical range of motion and pressure point sensitivity of latent myofascial trigger points (MTrPs).

Design: A single-session, single-blind randomized trial.

Setting: General community rehabilitation clinic.

Participants: Individuals (N = 76; 45 men, 31 women) aged 18 to 41 years (mean ± SD, 23 ± 4y) with latent MTrPs in 1 upper trapezius muscle.

Interventions: Subjects were randomly divided into 2 groups: a TENS group that received a burst-type TENS (pulse width, 200 μs; frequency, 100 Hz; burst frequency, 2 Hz) stimulation over the upper trapezius for 10 minutes, and a placebo group that received a sham-TENS application over the upper trapezius also for 10 minutes.

Main outcome measures: Referred pressure pain threshold (RPPT) over the MTrP and cervical range of motion in rotation were assessed before, and 1 and 5 minutes after the intervention by an assessor blinded to subjects' treatment.

Results: The analysis of covariance revealed a significant group × time interaction (P < .001) for RPPT: the TENS group exhibited a greater increase compared with the control group; however, between-group differences were small at 1 minute (0.3 kg/cm²; 95% confidence interval [CI], 0.1-0.4) and at 5 minutes (0.6 kg/cm²; 95% CI, 0.3-0.8) after treatment. A significant group × time interaction (P=.01) was also found for cervical rotation in favor of the TENS group. Between-group differences were also small at 1 minute (2.0°; 95% CI, 1.0-2.8) and at 5 minutes (2.7°; 95% CI, 1.7-3.8) after treatment.

Conclusions: A 10-minute application of burst-type TENS increases in a small but statistically significant manner the RPPT over upper trapezius latent MTrPs and the ipsilateral cervical range of motion.