Updated: 6/4/2021

Thoracic Outlet Syndrome

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  • 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
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(OBQ06.247) A 35-year-old businessman complains of tingling and numbness in his fingers of both hands, mostly in the ring and small fingers, made worse with overhead activity. Neurologic exam and electromyography-nerve conduction study is normal. His x-ray is shown in figure A. What is the most likely diagnosis?

QID: 258
FIGURES:
1

C5-6 cervical disk herniation

1%

(14/2712)

2

C6-7 cervical disk herniation

3%

(77/2712)

3

Bilateral cubital tunnel syndrome

2%

(52/2712)

4

Bilateral radial tunnel syndrome

0%

(2/2712)

5

Thoracic outlet syndrome

94%

(2552/2712)

L 1 D

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