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Thoracic Outlet Syndrome

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Ovid: 5-Minute Sports Medicine Consult, The


Thoracic Outlet Syndrome
Kari Kindschi
Jeffrey R. Bytomski
Basics
Description
  • Neurogenic or vascular symptoms in the upper extremity due to compression of the neurovascular bundle (brachial plexus and subclavian vessels) by skeletal and/or muscular structures above the 1st rib and behind the clavicle
  • Symptoms are variable and based on the structure that is compressed or irritated.
  • 3 types:
    • Neurogenic: >95% of cases
    • Venous: 4% of cases
    • Arterial: <1% of cases
Risk Factors
  • Repetitive work
  • Overhead athletes: Swimmers, pitchers, weightlifters, volleyball and tennis players
  • Poor posture
  • Middle-aged female
  • Congenital abnormalities:
    • Cervical rib
    • Abnormally long transverse process of C7
    • Anomalous fibromuscular band in the thoracic outlet
  • Trauma
  • Obesity
Etiology
  • Brachial plexus nerve roots, subclavian artery, and subclavian vein pass through the scalene triangle formed by the 1st rib, anterior scalene muscles, and middle scalene muscles.
  • Increased risk of positional compression of the neurovascular bundle at the thoracic outlet due to:
    • Congenital anatomic predisposition (cervical rib, abnormally long transverse process of C7, anomalous fibromuscular band)
    • Acquired extrinsic factors (anterior scalene hypertrophy, pectoralis minor tightness, poor posture causing decreased diameter of the costoaxillary canal, trauma, shortening of the scalene muscles due to active trigger points)
  • Upper extremity venous thrombosis or Paget-Schroetter Syndrome:
    • Overhead athletes may develop “effort thrombosis” due to repetitive shoulder hyperabduction and external rotation which can compress the axillary-subclavian veins, damage the intimal lining, and transiently restrict venous flow. Over time, this creates a favorable environment for thrombus formation.
Diagnosis
Thoracic outlet syndrome is largely a clinical diagnosis.
History
  • Neurogenic and vascular symptoms related to certain positions
  • Worse with lifting heavy objects, overhead activities, shoulder abduction, and external rotation
  • Neurogenic:
    • Arm, shoulder, and neck pain
    • Paresthesias and numbness:
      • Frequently seen in the ulnar distribution
    • Headaches
    • Cramping of forearm muscles
    • Difficulty with fine motor skills of the hand
    • Sensory loss, motor weakness, atrophy (late findings)
    • Gilliatt-Sumner hand: Severe wasting of the abductor pollicis brevis and, to a lesser extent, the interossei and hypothenar muscles
  • Venous:
    • Pain
    • Edema
    • Cyanosis
    • Feeling of heaviness in the arm or hand
    • Venous distension of the arm and hand
  • Arterial (often asymptomatic until embolization occurs):
    • Ischemic pain
    • Paresthesias and numbness
    • Claudication
    • Cool extremity
    • Pallor
    • Decreased distal pulse
    • Pulsating lump above the clavicle
Physical Exam
  • Swelling or discoloration of the affected extremity
  • Muscle atrophy
  • Decreased or absent distal pulse with activity or position changes
  • Bruit auscultated in the supraclavicular space
  • Provocative testing (low overall sensitivity and specificity):
    • Elevated arm stress test: (1)[C]
      • Arms abducted above the head in a “stick-em-up” position
      • Patient opens and closes fists at moderate speed for 3 min
      • Positive test if position reproduces pain or paresthesias
    • Upper limb tension tests: (1)[C]
      • Position 1: Abduct arms to 90°
      • Position 2: Extend wrists
      • Position 3: Tilt head to 1 side—ear to shoulder—then tilt head to other side
      • Positions 1 and 2 should cause ipsilateral pain, and position 3 should cause contralateral pain.
      • Strongest response is an onset of symptoms with position 1 and an increase in severity with positions 2 and 3.
    • Adson maneuver (original diagnostic test described in the 1920s) (1)[C]:
      • Neck extended and turned to the affected side while the shoulder is slightly abducted and extended
      • Feel for radial pulse while patient takes a deep breath.
      • Positive test if pulse lost and symptoms reproduced
      • False positives are common.
    • Wright test:
      • Affected arm is progressively hyperabducted and externally rotated
      • Positive test if radial pulse lost
    • Allen test:
      • Flex elbow to 90°, abduct and externally rotate the shoulder
      • Patient rotates head away from the test arm
      • Positive test if radial pulse lost

P.581


Diagnostic Tests & Interpretation
Lab
Consider hypercoagulable workup in venous thoracic outlet syndrome and patients with arterial thrombosis (2,3)[C].
Imaging
  • X-rays of the cervical spine and chest: Useful to evaluate for a cervical rib or other thoracic pathology (2)[C]
  • X-rays of the shoulder (2)[C]
  • MRI: Helpful to determine the location and cause of compression or to identify an anomalous fibrous band (3)[C]
  • Duplex US: To document degree of stenosis, presence of an aneurysm, or confirm thrombosis (2,3)[C]
Diagnostic Procedures/Surgery
  • Electromyogram (3)[C]
  • Nerve conduction studies (3)[C]
  • Arteriography/venography: Reserved for cases of suspected arterial or venous thoracic outlet syndrome and for surgical planning (2)[C]
Differential Diagnosis
  • Cervical disc disorders
  • Rotator cuff tear/impingement syndrome
  • Brachial plexus neuritis
  • Carpal tunnel syndrome
  • Ulnar nerve entrapment
  • Complex regional pain syndrome
  • Polymyalgia rheumatica
  • Fibromyalgia
  • Subclavian steal
  • Vasculitis
  • Raynaud's disease
  • Multiple sclerosis
  • Tumors of the spinal cord
  • Pancoast tumor
  • Neurofibroma
Treatment
  • Conservative therapy is the initial approach, except in cases of thromboembolic phenomena with acute vascular occlusion, stenosis, arterial dilatation or progressive neurologic deficits.
  • Medications (2)[C]:
    • NSAIDs
    • Muscle relaxants
    • Tricyclic antidepressants or SSRIs
  • Activity modification (2)[C]
  • Weight loss (2)[C]
  • Physical therapy (2,3,4)[C]:
    • Postural retraining
    • Pectoral and scalene stretching/strengthening
    • Scapulothoracic mobility
    • Trigger point treatment
    • Soft tissue mobilization
  • Botox injections (3)[C]:
    • CT-guided injections into the scalene muscles
    • Consider as a short-term adjunct to nonoperative therapy with physical therapy or as a bridge to surgery
  • Venous thoracic outlet syndrome with thrombus present (3)[C]:
    • Thrombolytics and anticoagulation
Surgery/Other Procedures
  • Surgery is an option for neurogenic thoracic outlet syndrome that has not responded to aggressive nonoperative treatments or for patients with vascular compromise/thrombus formation (2,3)[C].
  • CT-guided scalene block with local anesthetic to relax the anterior scalene muscle and lower the 1st rib to relieve the tension on the brachial plexus. If the injection provides symptomatic relief, it indicates likely benefit of a 1st rib resection/anterior scalenectomy (2,3)[C].
Ongoing Care
Follow-Up Recommendations
  • Surgical referral if signs of vascular compromise or severe neurogenic symptoms are present
  • Surgical referral when a cervical rib or extra-long transverse process of C7 is associated with loss of sensation, muscle atrophy, or weakness
  • Surgical referral if symptoms persist despite an adequate course of aggressive therapy
Complications
  • Poststenotic dilatation of the subclavian artery resulting in aneurysm formation and the potential for thromboembolism to the affected upper extremity (arterial thoracic outlet syndrome)
  • Pulmonary embolism, residual symptoms and high recurrence rate (venous thoracic outlet syndrome)
  • Progressive motor deficits (neurogenic thoracic outlet syndrome)
References
1. Sanders RJ, Hammond SL, Rao NM. Diagnosis of thoracic outlet syndrome. J Vasc Surg. 2007;46:601–604.
2. Fugate MW, Rotellini-Coltvet L, Freischlag JA. Current management of thoracic outlet syndrome. Curr Treat Options Cardiovasc Med. 2009;11:176–183.
3. Nichols AW. Diagnosis and management of thoracic outlet syndrome. Curr Sports Med Rep. 2009;8:240–249.
4. Vanti C, Natalini L, Romeo A, et al. Conservative treatment of thoracic outlet syndrome. A review of the literature. Eura Medicophys. 2006.
Codes
ICD9
353.0 Brachial plexus lesions


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