Pectoralis Minor Syndrome: Subclavicular Brachial Plexus Compression

Abstract

The diagnosis of brachial plexus compression—either neurogenic thoracic outlet syndrome (NTOS) or neurogenic pectoralis minor syndrome (NPMS)—is based on old fashioned history and physical examination. Tests, such as scalene muscle and pectoralis minor muscle blocks are employed to confirm a diagnosis suspected on clinical findings. Electrodiagnostic studies can confirm a diagnosis of nerve compression, but cannot establish it. This is not a diagnosis of exclusion; the differential and associated diagnoses of upper extremity pain are always considered. Also discussed is conservative and surgical treatment options.

Thoracic Outlet Syndrome: Biomechanical and Exercise Considerations

“…There is generally no agreement on the etiology of TOS, which can make prescribing treatment for the condition difficult. Proper physical examination of the patient can help differentiate between the various forms of TOS, and other conditions that elicit similar symptoms of TOS (i.e., carpal tunnel syndrome or pectoralis minor syndrome) [ 17 , 19 , 20 ]. Approximately 90% of all TOS cases are diagnosed as nTOS [ 4 , 11 , 12 ].…”

“…Specifically, the sternocleidomastoid and scalenes shorten, which can alter the function of these muscles [ 22 ]. This can lead to an entrapment of the brachial plexus, subclavian artery, subclavian vein, or a combination of these vessels and tissues [ 2 , 19 ]. The subclavian artery and vein run posterior and inferior to the clavicle, and deep to the pectoralis minor [ 19 ].…”

“…This can lead to an entrapment of the brachial plexus, subclavian artery, subclavian vein, or a combination of these vessels and tissues [ 2 , 19 ]. The subclavian artery and vein run posterior and inferior to the clavicle, and deep to the pectoralis minor [ 19 ]. Both the clavicle and pectoralis minor muscle can influence shoulder motion.…”

The Art of Caring in the Treatment of Thoracic Outlet Syndrome

“…The diagnosis and treatment of pectoralis minor syndrome is discussed in detail by Sanders and Annest [ 10 ]. This anatomical variant of thoracic outlet syndrome is rare but can be differentiated from neurogenic thoracic outlet syndrome by symptoms and physical exam, especially tenderness found in the axillary area.…”

Compression of the neurovascular bundle above and below the clavicle

“…Its recognition is important, as many patients with suspected neurogenic TOS can be treated successfully by simple, essentially risk-free, pectoralis minor tenotomy. Should this fail, thoracic outlet decompression can always be performed at a later date [9].…”