Summary Thoracic outlet syndrome is a neurovascular disorder resulting from compression of the brachial plexus and/or subclavian vessels in the interval between the neck and axilla. Diagnosis can be suspected clinically with specific provocative tests and supplemented with radiographs or vascular studies. showing anatomic causes of compression. Treatment may be nonoperative or include surgical decompression or a vascular procedure depending on the specific etiology. Epidemiology Incidence 1-2% of the population Demographics females > males (3:1) tend to be thin with long necks and drooping shoulders age 20-60 Etiology Type neurogenic is most common (95%) vascular may be venous (4%) or arterial (< 1%) more common in athletic males compared to athletic females Pathophysiology most cases are thought to stem from anatomic predisposition with superimposed neck trauma (acute or chronic repetitive stress) anatomically, can be organized into soft tissue (70%) and osseous (30%) abnormalities soft tissue scalene muscle abnormalities hypertrophy of anterior scalene passage of the brachial plexus through the anterior scalene muscle rather than posterior within the interscalene triangle variable origin and insertion anterior insertion of the middle scalene muscle on the 1st rib scalenus minimus accessory muscle found in 30-50% of patients with TOS originates from cervical transverse process and inserts onto 1st rib between the subclavian artery and T1 root anomalous ligaments or bands fibromuscular bands increase stiffness and decrease compliance of the thoracic outlet costoclavicular ligament abnormal insertion implicated in Paget-Schroetter syndrome soft tissue tumors Pancoast tumor tumor of the pulmonary apex 1-3% of lung cancer cases generally lack typical symptoms of lung cancer (cough, hemopytsis and dyspnea) neuroblastomas schwannoma of the brachial plexus abnormal pectoralis minor osseous cervical rib occur in < 1% of the population arise from the 7th cervical vertebra four types type 1: complete rib that articulates with the first rib or manubrium type 2: incomplete rib with a free distal bulbous tip type 3: incomplete rib with distal attachment via fibrous band type 4: short bar of bone (millimeters) extending beyond the C7 transverse process prominent C7 transverse process abnormal clavicle or first rib acute fracture displacement hypertrophic fracture callus formation fracture malunion acromioclavicular (AC) or sternoclavicular (SC) joint injury or dislocation osseous tumors bone metastasis to first rib breast, prostate, kidney osteoid osteoma chronic overuse repetitive shoulder use frequent lifting above the level of the shoulder extreme arm positions, including hyperabduction athletes at risk weight lifting rowing swimming vascular repetitive compression over time can result vessel damage aneursym formation thrombosis embolic events limb-threatening ischemia Associated conditions Paget-Schroetter syndrome type of venous thoracic outlet syndrome seen in well-developed young athletes intermittent obstruction of the subclavian vein in the costoclavicular space by abnormal costoclavicular ligament anterior scalene muscle hypertrophy results in upper extremity deep vein thrombosis Anatomy Thoracic outlet comprised of three distinct spaces interscalene triangle proximal space borders anterior: anterior scalene muscle posterior: middle scalene muscle inferior: first rib contents brachial plexus trunks subclavian artery subclavian vein does not pass through interscalene triangle runs beneath anterior scalene muscle prior to entering the costoclavicular space costoclavicular space middle space separated from the interscalene triangle by the first rib borders anterior: clavicle and subclavius muscle posterior: first rib and scalene muscles medial: costoclavicular ligament lateral: upper scapular border contents brachial plexus divisions subclavian artery and vein retropectoralis minor space distal space also known as the thoraco-coraco-pectoral space or subcoracoid space borders superior: coracoid anterior: pectoralis minor muscle posterior: ribs 2-4 contents brachial plexus cords axillary artery and vein Presentation History presentation is very variable ranges from mild pain to sensory changes to severe vascular compromise can be unilateral or bilateral neurogenic pain over the neck, trapezius, chest, shoulder and/or arm 92% of patients endorse trapezius pain upper extremity weakness, numbness and paresthesias distribution differs from other compression syndromes nonradicular nature cervical nerve root compression presents with radicular pain wide anatomic distribution (plexus) isolated peripheral nerve compression (cubital tunnel syndrome, carpal tunnel syndrome) presents with a clear dermatomal distribution involves the lower plexus (C8-T1) or combined (C5-T1) in 90% of patients upper extremity paresthesias occur in 98% upper extremity heaviness particularly with overhead activities symptoms can be activity-related and/or occur at night-time night-time symptoms thought to result from decreased pressure on the brachial plexus with return of sensation manifesting as pain vascular venous episodic cyanotic discoloration and swelling of the limb distended veins diffuse deep pain in the arm and forearm upper extremity heaviness worse after activity arterial unilateral Raynaud-type symptoms episodic coolness and pallor of the limb, followed by cyanosis and ultimately erythema worsens in cold temperatures pain and numbness symptoms tend to predominantly involve the hand (distal circulation) Physical examination inspection note specific postures, can increase loading on the brachial plexus rounded shoulders increased thoracic kyphosis downward rotation or depression of the scapula skin cyanosis, congestion, pallor distal ulcerations, signs of microembolic events (rare) hair distribution nail changes muscle atrophy Gilliatt-Sumner hand characteristic finding of neurogenic TOS atrophy of the abductor pollicus brevis (APB), hypothenar muscles and interossei palpation over the supraclavicular area may reveal tenderness and/or masses skin temperature provocative tests high rate of false positives supraclavicular pressure test evaluates for compression at the interscalene triangle technique patient seated with arm resting at side apply pressure to upper trapezius and anterior scalene muscle, squeezing for 30 seconds positive result reproduction of pain or paresthesias Adson test evaluates for compression at the interscalene triangle technique patient seated with shoulder slightly abducted and externally rotated, elbow extended, forearm supinated examiner palpates radial pulse patient maximally extends and laterally rotates the neck towards side being tested, then inhales and holds breath positive result reduction in amplitude or loss of radial pulse 51% of normal population has diminished pulse with this manuever reproduction of pain or paresthesias costoclavicular manuever evaluates for compression at the costoclavicular space technique patient seated with the arm at the side, elbow extended, forearm supinated examiner palpates radial pulse patient retracts and depresses the bilateral shoulders, protruding the chest anteriorly and superiorly ("at attention" stance) examiner extends the shoulder ~30° for 1 minute positive result reduction in amplitude or loss of radial pulse reproduction of pain or paresthesias Wright test evaluates for compression at the retropectoralis minor space technique patient seated with arm at the side, elbow extended, forearm supinated examiner palpates radial pulse patient laterally rotates neck away from side being test examiner externally rotates and maximally abducts the shoulder, holding the arm above the level of the head for 1 minute positive result reduction in amplitude or loss of radial pulse 7% of the normal population has dimished or lost radial pulse with this manuever reproduction of pain or paresthesias Roos test / elevated arm stress test evaluates the entire thoracic outlet technique in seated position, patient abducts the bilateral shoulders to 90° with the elbow flexed 90° patient opens and closes the hands for 3 minutes positive result reproduction of pain or paresthesias will often prevent the patient from completing the test for the full 3 minutes normal person have discomfort with this manuever, but are able to complete it resolution of pain or paresthesias with dropping of the arms Cyriax release test evaluates the result of unloading the brachial plexus technique examiner stands behind patient and grasps the bilateral forearms with the elbows in flexion and forearms in pronation examiner leans against the patient's trunk to passively elevate the shoulder girdle for 3 minutes positive result reproduction of pain or paresthesias Evaluation Radiographs recommended views chest radiograph and cervical spine radiographs findings cervical rib prominent C7 transverse process low lying shoulder girdle Pancoast tumor CT indications identify osseous space-occupying lesions evaluate malunited fractures of the ribs or clavicle MRI indications evaluate for soft tissue anatomic anomalies Nerve conduction studies EMG and NCV historically thought to be equivocal and unhelpful studies were often normal unless significant permanent nerve damage was already established recently discovered that nerve fibers from C8 and T1 may show early changes in neurogenic TOS abnormal nerve conduction velocities in the medial antebrachial cutaneous nerve and median motor nerve to the abductor pollicis brevis Vascular studies doppler ultrasound helpful for evaluating subclavian vein for obstruction or thrombosis 92% specificity and 95% sensitivity for diagnosis of venous TOS angiography CT or MR angiography arteriography indicated in cases of embolic disease or suspected arterial aneursym venography indicated in work up of suspected subclavian or axillary venous thrombosis Treatment Nonoperative activity modification, pain control, physical therapy and modalities indications first line of treatment technique activity modification to avoid provocative activities limiting repetitive overhead motion changing employment if necessary pain control NSAIDs, muscle relaxants physical therapy core and back strengthening, shoulder girdle strengthening, improving posture and relaxation techniques modalities transcutaneous electrical nerve stimulation outcomes less successful in obese patients patients on worker's compensation patients with double-crush neurologic pathology involving the carpal or cubital tunnels anterior scalene blocks indications neurogenic TOS related to scalene muscule contracture technique ultrasound-guided lidocaine or botulinum toxin injections outcomes successful block correlates with 14% higher rate of good surgical outcomes Operative thoracic outlet decompression indications symptoms that have failed conservative treatment for 6 months progressive muscle atrophy and/or worsening neurologic deficits technique decompression includes a combination of the following depending on etiology first rib resection, anterior and middle scalenectomy, neurolysis most common procedure 95% good outcomes isolated scalenectomy indications upper plexus symptoms absence of abnormal bony architecture excessively muscular or obese patients recurrent TOS following prior first rib resection isolated pectoralis minor tenotomy indications neurogenic TOS with symptoms reproducible to the retropectoralis minor spacw cervical rib resection release of fibromuscular bands costoclavicular ligament resection ORIF of clavicle malunion vascular intervention indications embolic events stenosis with persistent pain and vascular insufficiency subclavian aneursym thrombosis with critical ischemia technique indications heparin IV, +/- embolectomy, +/- local thrombectomy, +/- TPA, systemic anticoagulation acute embolic event small vessel embolism - TPA, systemic anticoagulation large / proximal vessel embolism - embolectomy, systemic anticoagulation endovascular stent placement mild stenotic disease vascular resection +/- primary repair, +/- saphenous vein graft, +/- arterial autograft, +/- synthetic graft subclavian aneursym severe stenosis or thrombosis with critical ischemia vascular bypass chronic emboli with critical ischemia Technique Thoracic Outlet Decompression approaches transaxillary most commonly used approach pros superior exposure for the first rib resection allows resection of cervical ribs, costoclavicular ligament, fibromuscular bands and scalene muscles access to lower plexus for neurolysis (C7-T1) more cosmetic scar no retraction of neurovascular structures necessary for first rib removal cons risks brachial plexus injury supraclavicular pros superior exposure of upper plexus (upper and middle trunks), scalene muscles, neck of the first rib and vascular structures best approach for isolated scalenectomy and arterial reconstruction allows resection of first rib (but requires significant retraction) cons inferior visualization for first rib resection requries retraction of brachial plexus and vascular structures for complete first rib exposure posterior pros favored for recurrent TOS and in cases of prior neck surgery may allow better exposure of proximal elements of the brachial plexus cons requires extensive muscle dissection that can lead to postoperative shoulder disfunction risks injury to the long thoracic, dorsal scapular and accessory nerves decompression techniques first rib resection, anterior and middle scalenectomy, neurolysis usually performed with combined approach transaxillary: to access first rib and lower plexus supraclavicular: to access anterior and middle scalene muscles and upper plexus specific complications pneumothorax is one of the most common complications of first rib resection Complications Pneumothorax is one of the most common complications of first rib resection