Low-frequency high-intensity versus medium-frequency low-intensity combined therapy in the management of active myofascial trigger points: A randomized controlled trial.

BACKGROUND: Electrotherapeutic modalities have proven to be one of the best therapeutic options for myofascial pain syndrome, targeting the myofascial trigger points (MTrPs). Combined therapy (CT) is described with paucity in literature as the application of ultrasound (US) and electrical stimulating current concurrently and at the same site.

AIM: The aim was to compare between low-frequency, high-intensity burst transcutaneous electrical nerve stimulation CT (burst-TENS-CT) and medium-frequency, low-intensity amplitude modulated frequency CT (AMF-CT) on upper trapezius active MTrPs (A-MTrPs).

PARTICIPANTS AND INTERVENTION: In this single-blinded randomized controlled trial design, 70 participants with acute mechanical neck pain and at least two A-MTrPs in the upper trapezius were simply and randomly allocated into three groups-the burst-TENS-CT, the AMF-CT, or the sham-CT control groups. All groups received three sessions per week for four consecutive weeks.

OUTCOME MEASURES: Outcome measures included pressure pain threshold (PPT) using a digital electronic algometer and active cervical lateral flexion range of motion (ROM) using an iPhone Clinometer application. Data were collected prior to the first treatment and at the end of the 4-week trial.

RESULTS: There were statistically significant improvements in postintervention PPT and ROM values in both treatment groups (p < 0.0001). As for the sham-US, no significant difference was found between the preintervention and postintervention values (p > 0.05). Bonferroni correction test revealed that there was a significant difference between all the three groups (p < 0.0001). Additionally, burst-TENS-CT yields a greater increase in PPT and ROM values (547% and 49.32%, respectively) than that of medium-frequency AMF-CT.

CONCLUSION: Within the scope of this study, both CT modalities were effective in increasing PPT and cervical lateral flexion ROM. Nonetheless, low-frequency, high-intensity burst-TENS-CT was shown to be superior over the medium-frequency, low-intensity AMF-CT in terms of reducing pain sensitivity and increasing ROM.