Delayed-Onset Postsurgical Myofascial Pain Following Axillary Artery Cannulation: A Case Report.

Chronic postsurgical pain (CPSP) is often attributed to neuropathic, genetic, or psychosocial factors, whereas musculoskeletal causes, such as myofascial pain syndrome (MPS), are frequently overlooked. We report a case of delayed-onset MPS as a musculoskeletal manifestation of CPSP following axillary artery cannulation, aiming to raise awareness of this potential etiology. A 48-year-old man developed persistent right anterior chest pain one year after total arch replacement surgery. Physical examination revealed postural asymmetry, atrophy of the right pectoralis major muscle, mechanical allodynia, and myofascial trigger points (MTrPs) near the cannulation site and scapula. Ultrasonography demonstrated the disrupted architecture of the pectoralis major and adjacent connective tissue. Based on clinical and sonographic findings, MPS was diagnosed. Treatment included pregabalin, ultrasound-guided trigger point injections (TPIs) with levobupivacaine and triamcinolone, and type II pectoral nerve blocks. Five biweekly sessions led to significant pain relief, resolution of allodynia, and improved posture. This case highlights the importance of recognizing delayed-onset MPS as a musculoskeletal manifestation of CPSP following axillary artery cannulation, likely related to localized muscle trauma and pectoral nerve injury, and supports the value of multimodal management.