Application of Ultrasound-Guided Trigger Point Injection for Myofascial Trigger Points in the Subscapularis and Pectoralis Muscles to Post-Mastectomy Patients: A Pilot Study

PURPOSE To investigate the therapeutic effectiveness of ultrasound (US)-guided trigger point injection for myofascial trigger points (MTrPs) in the internal rotator muscles of the shoulder in post-mastectomy patients. MATERIALS AND METHODS This pilot study was a non-controlled, prospective, clinical trial. Nineteen post-mastectomy patients with a diagnosis of at least one active MTrP in the subscapularis and/or pectoralis muscles were included. We performed trigger point injections into the subscapularis muscle deep behind the scapula as well as the pectoralis muscle for diagnostic and therapeutic purpose by the newly developed US-guided method. RESULTS Visual analogue scale and range of motion of the shoulder for external rotation and of abduction showed significant improvement immediately after the first injection and 3 months after the last injection compared with baseline (p<0.05 for both). Duration from onset to surgery and duration of myofascial pain syndrome in the good responder group were significantly shorter than in the bad responder group (p<0.05). Patients did not report any complications related to the procedure or serious adverse events attributable to the treatment. CONCLUSION In post-mastectomy patients with shoulder pain, US-guided trigger point injections of the subscapularis and/or pectoralis muscles are effective for both diagnosis and treatment when the cause of shoulder pain is suspected to originate from active MTrPs in these muscles, particularly, the subscapularis.