Case Study: Exercise-Induced Chest and Shoulder Pain

Our Patient

Our patient is a young adult male reporting severe chest pain after experiencing a tearing sensation during a repetitive chest exercise.

The Challenge

MRI revealed no tissue tearing. Electromyography (EMG) and Nerve Conduction Velocity (NCV) tests were negative. Various factors were causing the condition to worsen, and doctors were unable to arrive at a credible diagnosis.

Our Diagnostic Process

Clinical Exam

Our clinical exam revealed left-sided weakness, paresthesia (tingling and numbness), and anxiety-driven guarding of the left chest and shoulder region, affecting posture. Extreme allodynia (hypersensitivity) and guarding made traditional strength testing, thoracic outlet maneuvers, and scapular assessment unreliable. 

What we found:

• Severe rib flaring
• Paradoxical respiration (abnormal breathing)
• Anterior scapular tilt
• Protective arm positioning to unload the neck and chest muscles

Ultrasound Exam

Our exam with high-resolution dynamic ultrasound gave us more insight. 

Diagnostic ultrasound key findings:

• Fibrosis (not fatty infiltration) of the pectoralis minor muscle
• Patchy fatty infiltration of sternal/clavicular fibers of pectoralis major
• Normal appearance of pectoral tendons, subclavius, cervical roots (C4–C8), and major plexus branches
• Dynamic shoulder extension and abduction produced sharp pain with visible indentation/compression of brachial plexus cords in the retro-pectoralis minor space
• Disproportionate size and stiffness of the pectoralis minor muscle relative to the pectoralis major

Our Diagnosis

We concluded that the patient had Pectoralis Minor Syndrome (PMS) – a type of Thoracic Outlet Syndrome (TOS) where the pectoralis minor compresses the nerves and blood vessels of the brachial plexus. The condition was exacerbated by central sensitization, where the nerves become hypersensitive, sending exaggerated pain signals to the brain. We also suspected chronic tethering/compression of the lower brachial plexus (C8–T1), despite a normal EMG.

Our Next Steps

We mapped out the following assessment/treatment strategy for our patient:

• Lower plexus evaluation using MR neurography – an advanced MRI technique for visualizing nerves.
• Targeted retro-pectoral / claviopectoral fascial hydrodissection to liberate compressed nerves.
• Possible botox injections to temporarily deactivate the pectoralis minor, if necessary. 
• Reassessment of scapular dyskinesis and remote plexus stretch injury, once pain inhibition improves.

We injected the infraclavicular plexus and performed hydrodissection of the fascial planes where multiple nerves were stranded. After a few injections, pain was relieved enough that we were able to conduct tests to understand what physical therapy was needed to correct the condition. After four months of therapy, the patient is completely pain free. 

Discussion

Chronic chest and shoulder pain does not necessarily indicate a myofascial or fibromyalgia problem. The missing piece is sometimes dynamic neuro-mechanical compression. A normal EMG does not necessarily rule out clinically significant brachial plexus compression, and static imaging can overlook factors that can be instantly seen with dynamic high-resolution ultrasonography.

Pectoralis Minor Syndrome (PMS) and retro-pectoral plexus compression are frequently overlooked when diagnosing chronic chest and shoulder pain. Labeling complex neuro-mechanical pain as “fibromyalgia” without evaluating dynamic nerve–muscle–fascia interactions can lead to mistreatment, delaying meaningful care. 

When used early-on, dynamic diagnostic ultrasound can completely change the clinical trajectory, saving the patient from misdiagnosis and ineffective treatment.