Received Date: April 25, 2012; Accepted Date: May 16, 2013; Published Date: May 18, 2013
Citation: Bavare CS, Naoum JJ (2013) Pectoralis Minor Compression of the Axillary Vein–Anatomy of a Problem and its Solution. J Vasc Med Surg 1:105. doi:10.4172/2329-6925.1000105
Copyright: © 2013 Bavare CS, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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We report a case of symptomatic axillary vein compression by the pectoralis minor muscle mimicking upper extremity thoracic outlet syndrome (TOS). The cause of obstruction was determined by clinical findings and dynamic venography. The patient underwent division of the pectoralis minor muscle with resolution of venographic findings and symptoms. Pectoralis minor compression of the axillary vein is a rare but described entity that needs careful review to reach the correct diagnosis and establish proper treatment.
Pectoralis minor syndrome, also called “hyper abduction syndrome”, is a rare but documented entity mimicking thoracic outlet syndrome (TOS) symptoms. Rarer still, is non-thrombotic axillary vein obstruction due to compression by the pectoralis minor muscle (PMM). Wright  in 1945 introduced the term pectoralis minor syndrome as a neurovascular syndrome produced by hyper abduction of the arms. His manuscript focused on the arterial system. Venography was not performed in the described patients, but was suggested that it would be of interest in cases with axillary vein involvement. Limited evidence exists about the condition, but it was not until 2007 that Sanders and colleagues  documented dynamic obstruction of the axillary vein on venography. Surgical division of the pectoralis minor insertion, also known as pectoralis minor tenotomy (PMT) was shown to be the treatment of choice. A high index of suspicion is needed to diagnose pectoralis minor syndrome and it should be alerted by the finding of axillary vein compression.
A 19-year-old man presented with intermittent left arm pain, bluish coloration and swelling. The pain was throbbing and radiating to the left side of the neck, shoulder and scapula. It was exacerbated by elevation of the left arm and increasing activity. On physical exam symptoms were duplicated with hyper-abduction of the shoulder to 180 degrees. Wasting of hand muscles was not seen and no significant change in the radial pulse was observed with provocative maneuvers. Plain x-rays of the chest and cervical spine were normal, as were previous magnetic resonance imaging of the neck and nerve conduction studies. Color flow duplex did not show thrombosis, but showed decreased respiratory phasicity in the brachial vein, with the arm abducted to 90 degrees. Venography showed external compression of the left axillary vein on abduction of the shoulder to 180 degrees, which was not seen on adduction. The patient underwent a division of the left PMM by an infra-clavicular approach and completion venography (Figure 1). At 1 and 3 month follow-up the patient had complete resolution of clinical symptoms and without a perioperative complication.
Axillary vein compression by the PMM is a rare condition. Lord and Stone  first reported five patients undergoing pectoralis minor division along with scalenotomy to treat pectoralis minor syndrome. Three patients had typical symptoms of arm pain or tightness along with arm swelling. Although surgery relieved the pain, the swelling persisted. Venography was not documented. Hewitt  described the first instance of pectoralis minor division without scalenectomy for the treatment of acute axillary vein compression. Sachatello  demonstrated a causal agent to be an anatomical variant band of muscle, extending from the latissimus dorsi muscle to the insertion of the PMM. Daskalakis and Bouhoutsos  described five patients with non-thrombotic compression of the axillary vein due to a variety of factors such as PMM and mal-union of the clavicle. Evans et al.  used dynamic venography to illustrate vein compression with hyper abduction of the arm. The authors demonstrated an anomalous band of fascia from the biceps muscle, division of which relieved the compression of the axillary vein. In addition, Sanders and Rao  described a series of six patients with axillary vein thrombosis for whom PMT provided relief of symptoms. Completion dynamic venography was done in half of those patients and demonstrated resolution of the stenosis.
Pectoralis minor nerve block has been documented to be a useful adjunct for the diagnosis of pectoralis minor syndrome, with relief of symptoms expected to be seen following the local infiltration of lidocaine . The nerve block can be used as an indirect confirmation that division of the muscle would provide symptom relief. Pectoralis minor muscle block is performed by injecting 1% lidocaine into the muscle. The point of injection is determined approximately 3 cm below the clavicle. A needle is inserted at a 45-degree angle upward to avoid the pleura, aiming toward the coracoid process. The medial pectoral nerve enters the deep surface of the pectoralis minor, where it divides into a number of branches. The muscle block affects these nerve branches and relaxes the pectoralis minor muscle fibers. When the muscle is in its relaxed position, it does not exert downward compression on its underlying structures; in this case the axillary vein. This was not carried out in our patient.
Color flow duplex showed decreased respiratory phasicity in the brachial vein with the arm abducted to 90 degrees. Though more invasive, we believe that patients with the symptoms of unilateral extremity pain and swelling in whom venous obstruction is suspected should undergo dynamic venography. In our patient, dynamic venography confirmed the external compression of the left axillary vein. Additionally, inpatients presenting with arm pain and swelling in which pectoralis minor syndrome is suspected, apectoralis minor block can be performed. If this leads to symptom improvement or resolution, it emphasizes the cause of axillary compression being the pectoralis minor muscle. A high index of suspicion for axillary vein compression would warrant a surgical decompression by a PMT. Table 1 summarizes the characteristic features for the diagnosis and treatment of this condition.
|PECTORALIS MINOR SYNDROME (Axillary vein compression)|
|ANATOMIC ETIOLOGY||Compression of the axillary vein by the pectorlis minor muscle|
|SYMPTOMS||Arm swelling, pain, cyanosis, or tightness|
|PHYSICAL FINDINGS||-Hyperabduction of the arm may reproduce symptoms without a change in distal arterial perfusion
-Arms swelling or cyanosis.
-Venous collaterals in the upper arm or shoulder
|DIAGNOSTIC TESTING||-Nerve conduction studies (evaluate nerve compression)
|TREATMENT||Pectoralis minor tenotomy|
Table 1: Characteristicfeatures of Pectoralis Minor Syndrome with axillary vein compression.
Non-thrombotic axillary vein compression is an unusual entity causing upper extremity swelling and pain. Diagnosis can be made by a thorough history and physical exam ultimately followed by dynamic venography. Pectoralis minor tenotomy is a safe procedure that leads to resolution of symptoms.