Pectoralis muscle injection is a useful diagnostic and therapeutic procedure for myofascial pain.
After informed consent is obtained, the patient is placed in the supine position. The pectoralis muscles are palpated. The injection sites are identified as points of maximal tenderness to deep palpation, reproducing the patient’s pain complaints. This may or may not result in referred pain. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 1½-in. (4-cm), 21- to 25-gauge needle is inserted at the point of maximal tenderness and advanced to the area of the trigger point. After negative aspiration, the trigger point area is injected with 4 mL of local anesthetic (Fig. 67-26).
FIGURE 67-26. Pectoralis. Trigger points and referred pain patterns.
The referred pain pattern for the pectoralis muscles usually involves the anterior chest wall and breast regions. The patient should be fully familiar with the stretching program for the pectoralis muscle and be instructed in the home program. Failure to include a home stretching program usually results in short-term relief.
Significant complications are uncommon with pectoralis trigger point injections; however, the anatomy of the region, including the close proximity of the thoracic cavity, must be carefully considered. The risk for pneumothorax is reduced by approaching the trigger point with the needle tangential to the thoracic wall.