Randomized controlled study of the antinociceptive effect of ultrasound on trigger point sensitivity: novel applications in myofascial therapy?

OBJECTIVE

To investigate whether therapeutic ultrasound modulates the pain sensitivity of myofascial trigger points.

DESIGN

Repeated measures, single-blinded randomized controlled trial of ultrasound treatment of trigger points.

SETTING

Outpatient injury rehabilitation clinic.

SUBJECTS

Forty-four patients (22 males, 22 females) with trigger points identified within the trapezius muscle.

INTERVENTIONS

Five-minute therapeutic intensity of ultrasound versus 5-min low-intensity application of ultrasound to a trapezius myofascial trigger point locus.

MAIN MEASURES

Pain pressure threshold readings were measured at the trapezius trigger point site before and after exposure to the ultrasound intervention.

RESULTS

Pain pressure threshold scores increased an average of 44.4 (14.2)% after therapeutic exposure to ultrasound (pre-ultrasound test 35.4 (8.5) N, post-ultrasound test 51.1 (12.8) N). No significant difference in pain pressure threshold scores was observed with low-intensity ultrasound exposures (pre-ultrasound 36.1 (6.1) N, post-ultrasound 36.6 (4.8) N).

CONCLUSIONS

Therapeutic exposures to ultrasound reduce short-term trigger point sensitivity. Ultrasound may be a useful clinical tool for the treatment and management of trigger points and myofascial pain syndromes.