AUTHOR AND EDITOR INFORMATION

Section 1 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• References

INTRODUCTION

Section 2 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• References

Background

Thoracic outlet syndrome (TOS) is a broad term that refers to compression of the neurovascular structures in the area just above the first rib and behind the clavicle. It represents a constellation of symptoms. The cause, diagnosis, and treatment are controversial. The brachial plexus (95%), subclavian vein (4%), and subclavian artery (1%) are affected. Most presentations to the emergency department (ED) are nonemergent and require only symptomatic treatment and referral.

Pathophysiology

The brachial plexus trunks and subclavian vessels are subject to compression or irritation as they course through 3 narrow passageways from the base of the neck toward the axilla and the proximal arm. The most important of these passageways is the interscalene triangle, which is also the most proximal. This triangle is bordered by the anterior scalene muscle anteriorly, the middle scalene muscle posteriorly, and the medial surface of the first rib inferiorly. This area may be small at rest and may become even smaller with certain provocative maneuvers. Anomalous structures, such as fibrous bands, cervical ribs, and anomalous muscles, may constrict this triangle further. Repetitive trauma to the plexus elements, particularly the lower trunk and C8-T1 spinal nerves, is thought to play an important role in the pathogenesis of TOS.

The second passageway is the costoclavicular triangle, which is bordered anteriorly by the middle third of the clavicle, posteromedially by the first rib, and posterolaterally by the upper border of the scapula.

The last passageway is the subcoracoid space beneath the coracoid process just deep to the pectoralis minor tendon.

Frequency

United States

Because no objective confirmatory test is available for TOS, there is much disagreement with regards to its true incidence, with reported figures ranging from 3-80 cases per 1000 people.

Sex

The sex ratio varies depending on the type of TOS (eg, neurologic, venous, arterial). Overall, the entity is approximately 3 times more common in women than in men.

• Neurologic - Female-to-male ratio approximately 3.5:1
• Venous - More common in males than in females
• Arterial - No sexual predilection

Age

The onset of symptoms usually occurs in persons aged 20-50 years.

CLINICAL

Section 3 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• References

History

• Neurologic symptoms occur in 95% of cases. The lower 2 nerve roots of the brachial plexus, C8 and T1, are most commonly (90%) involved, producing pain and paresthesias in the ulnar nerve distribution.
• The second most common anatomic pattern involves the upper 3 nerve roots of the brachial plexus, C5, C6, and C7, with symptoms referred to the neck, ear, upper chest, upper back, and outer arm in the radial nerve distribution.
• Neurologic
• • Pain, particularly in the medial aspect of the arm, forearm, and the ring and small digits
  • Paresthesias, often nocturnal, awakening the patient with pain or numbness
  • Loss of dexterity
  • Cold intolerance
  • Occipital headache
  • Weakness
  • Raynaud phenomenon, hand coldness, and color changes may also be seen, usually due to an overactive sympathetic nervous system as opposed to ischemia.
  • Most have a history of neck trauma preceding their symptoms, most commonly from auto accidents and repetitive stress at work.
• Venous - Pain, often in younger men and often preceded by excessive activity in the arms
• • Swelling of the arm
  • Cyanosis
  • Paresthesias in the fingers and hand (may be secondary to swelling as opposed to nerve compression)
• Arterial
• • Pain
  • Claudication
  • Pallor
  • Coldness
  • Paresthesias
  • Often in young adults with a history of vigorous arm activity
  • Symptoms usually develop spontaneously from arterial emboli.

Physical

In most cases, the physical examination findings are completely normal. Other times, the examination is difficult because the patient may guard the extremity and exhibit giveaway-type weakness. The sensory examination is often unreliable.

• Provocative tests, such as the Adson, costoclavicular, and hyperabduction maneuvers, are unreliable. Approximately 92% of asymptomatic patients have variation in the strength of the radial pulse during positional changes.
• The elevated arm stress test (EAST) is of debatable use, but it may be the most reliable screening test. It evaluates all 3 types of thoracic outlet syndrome (TOS).
• • To perform this test, the patient sits with the arms abducted 90 degrees from the thorax and the elbows flexed 90 degrees. The patient then opens and closes the hands for 3 minutes.
  • Patients with TOS cannot continue this for 3 minutes because of reproduction of symptoms. Patients with carpal tunnel syndrome experience dysesthesias in the fingers, but do not have shoulder or arm pain.
• Neurologic
• • A typical patient is a young, thin female with a long neck and dropping shoulders.
  • A positive EAST result and the presence of a radial pulse are strong indicators of neurologic involvement of the brachial plexus.
  • Supraclavicular tenderness may be present.
  • Usually, no evidence of muscle atrophy is present, although the classic finding is known as the Gilliatt-Sumner hand, with the most dramatic atrophy in the abductor pollicis brevis, with lesser involvement of the interossei and hypothenar muscles.
  • Paresthesias/sensory loss is restricted to the ulnar aspect of the hand and forearm.
  • Weakness (usually subtle) of affected limb may be noted.
• Venous
• • Edema of the upper extremity
  • Cyanosis of the upper extremity
  • Distended superficial veins of the shoulder and chest
• Arterial
• • Pallor and pulselessness
  • Coolness on the affected upper extremity
  • Lower blood pressure in affected arm of greater than 20 mm Hg (a reliable indicator of arterial involvement)
  • Rarely can produce multiple small infarcts on the hand and fingers (embolization)

Causes

The 3 major causes of TOS are anatomic, trauma/repetitive activities, and neurovascular entrapment at the costoclavicular space.

• Anatomic
• • Scalene triangle: Anterior scalene muscle frontally, middle scalene muscle posteriorly, and the upper border of the first rib inferiorly account for most cases of neurologic and arterial TOS.
  • Cervical ribs are found in most arterial cases but rarely in venous and neurologic cases.
  • Congenital fibromuscular bands are noted in as many as 80% of patients with neurologic TOS.
  • Transverse process of C7 is elongated.
• Trauma or repetitive activities
• • Motor vehicle accident hyperextension injury, with subsequent fibrosis and scarring
  • Effort vein thrombosis (ie, spontaneous thrombosis of the axillary veins following vigorous arm exertion)
  • Playing a musical instrument: Musicians can be particularly susceptible owing to their need to maintain the shoulder in abduction or extension for long periods.
• Neurovascular entrapment: This occurs in the costoclavicular space between the first rib and the head of the clavicle.

DIFFERENTIALS

Section 4 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• References

Other Problems to be Considered

Cervical spondylitis
Mediastinal venous obstruction (eg, Pancoast tumor)
Brachial plexitis
Fibromyalgia
Postural palsy
Raynaud disease
Trauma
Ulnar nerve compression at the elbow
Vasculitis
Vasospastic disorder

WORKUP

Section 5 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• References

Lab Studies

• With the rare exception of a vascular cause, the vast majority of ED presentations are not emergent. Screening tests may be appropriate if indicated and to rule out other causes. Once the clinical diagnosis is made, most of the imaging studies and other tests should be reserved for the outpatient setting.

Imaging Studies

• Cervical radiography - May demonstrate a skeletal abnormality
• Chest radiography
• • Cervical or first rib: This is usually associated with the arterial form of TOS but also can be a predisposition to developing the neurologic form following neck trauma.
  • Clavicle deformity
  • Pulmonary disease
  • Pancoast tumor
• Color flow duplex scanning for suspected vascular thoracic outlet syndrome (TOS)
• Arteriography (indications)
• • Evidence of peripheral emboli in the upper extremity
  • Suspected subclavian stenosis or aneurysm (eg, bruit or abnormal supraclavicular pulsation)
  • Blood pressure differential greater than 20 mm Hg
  • Obliteration of radial pulse during EAST
• Venography (indications)
• • Persistent or intermittent edema of the hand or arm
  • Peripheral unilateral cyanosis
  • Prominent venous pattern over the arm, shoulder, or chest

Other Tests

• The following special studies are generally appropriate in the outpatient setting. They should be arranged by the primary care physician once the patient has been discharged from the ED.
• • Nerve conduction evaluation via root stimulation and F wave is the best direct approach to evaluation of neurologic TOS.
  • Electromyography (EMG) is unreliable and does not provide objective evidence of TOS.
  • Cervical myelogram, CT scan, or MRI may be appropriate for patients suspected of having cervical disk disease or spinal cord disease.

TREATMENT

Section 6 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• References

Emergency Department Care

Most presentations to the ED are nonemergent and require only symptomatic treatment and referral. Vascular thoracic outlet syndrome (TOS), although much less common than neurologic TOS, requires more urgent care.

• Vascular (arterial and venous)
• • Immediate heparinization
  • Vascular surgery consultation
  • Color flow duplex scanning
  • Angiography or venography
• Neurologic - Conservative outpatient physiotherapy

Consultations

• Neurologic, orthopedic, or vascular surgery consultation(s) may be indicated depending on the type of pathologic condition.
• Physical medicine and rehabilitation physicians are needed for outpatient workup.

MEDICATION

Section 7 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• References

In patients with evidence of arterial or venous involvement (ischemia or thrombosis), immediate heparinization is indicated.

Drug Category: Anticoagulants

These agents prevent recurrent or ongoing thromboembolic occlusion of the vertebrobasilar circulation.

Drug Name	Warfarin (Coumadin)
Description	Interferes with hepatic synthesis of vitamin K–dependent coagulation factors. Used for prophylaxis and treatment of venous thrombosis, pulmonary embolism, and thromboembolic disorders. Tailor dose to maintain INR in range of 2-3. Infants may require doses at, or near, high end of range.
Adult Dose	5-15 mg/d PO qd for 2-5 d; adjust dose according to desired INR
Pediatric Dose	0.05-0.34 mg/kg/d PO; adjust dose according to desired INR
Contraindications	Documented hypersensitivity; severe liver or kidney disease; open wounds; GI ulcers
Interactions	Drugs that may decrease anticoagulant effects include griseofulvin, carbamazepine, glutethimide, estrogens, nafcillin, phenytoin, rifampin, barbiturates, cholestyramine, colestipol, vitamin K, spironolactone, oral contraceptives, and sucralfate Medications that may increase anticoagulant effects include oral antibiotics, phenylbutazone, salicylates, sulfonamides, chloral hydrate, clofibrate, diazoxide, anabolic steroids, ketoconazole, ethacrynic acid, miconazole, nalidixic acid, sulfonylureas, allopurinol, chloramphenicol, cimetidine, disulfiram, metronidazole, phenylbutazone, phenytoin, propoxyphene, sulfonamides, gemfibrozil, acetaminophen, and sulindac
Pregnancy	D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions	Do not switch brands after achieving therapeutic response; caution in active tuberculosis or diabetes; patients with protein C or S deficiency are at risk of developing skin necrosis

Drug Category: Tricyclic antidepressants (TCAs)

If analgesic treatment is ineffective, a short, monitored course of TCAs can be helpful if the time course and symptoms suggest a protracted pain syndrome. The primary care physician or neurologist (not the ED physician) should be the one to prescribe such therapy.

Drug Category: Analgesics

Pain control is essential to quality patient care. It ensures patient comfort, promotes pulmonary toilet, and enables physical therapy regimens. Many analgesics have sedating properties, which are beneficial for patients who have sustained injuries.

Drug Name	Acetaminophen and codeine (Tylenol with codeine)
Description	Drug combination indicated for treatment of mild to moderately severe pain.
Adult Dose	30-60 mg/dose based on codeine content PO q4-6h or 1-2 tab q4h; not to exceed 12 tabs in 24h
Pediatric Dose	0.5-1 mg/kg/dose based on codeine PO q4-6h; 10-15 mg/kg/dose based on acetaminophen content; not to exceed 2.6 g/d of acetaminophen
Contraindications	Documented hypersensitivity
Interactions	CNS depressants or tricyclic antidepressants increase toxicity
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Caution in patients dependent on opiates, since this substitution may result in acute opiate-withdrawal symptoms; caution in severe renal or hepatic dysfunction

Drug Name	Ibuprofen (Motrin, Ibuprin, Nuprin, Advil)
Description	DOC for patients with mild to moderately severe pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.
Adult Dose	200-400 mg PO q4-6h while symptoms persist; not to exceed 3.2 g/d
Pediatric Dose	<6 months: Not established 6 months to 12 years: 30-70 mg/kg/d divided PO tid/qid; not to exceed 2.4 g/d >12 years: Administer as in adults
Contraindications	Documented hypersensitivity; peptic ulcer disease; recent GI bleeding or perforation; renal insufficiency; high risk of bleeding
Interactions	Aspirin increases risk of inducing serious NSAID-related adverse effects; probenecid may increase concentrations and, possibly, toxicity; may decrease effects of hydralazine, captopril, and beta-blockers; may decrease diuretic effects of furosemide and thiazides; may increase PT in patients taking anticoagulants—monitor PT closely and instruct patients to watch for signs of bleeding; may increase risk of methotrexate toxicity; may increase phenytoin levels
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions	Caution in congestive heart failure, hypertension, and decreased renal and hepatic function; caution in coagulation abnormalities or during anticoagulant therapy

FOLLOW-UP

Section 8 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• References

Further Inpatient Care

• Vascular
• • Angiography or venography
  • Color flow duplex scanning
  • Catheter-directed local infusion of thrombolytic agent
  • Thrombectomy (for total thrombotic obstruction)
  • Fogarty catheter embolectomy
  • Emergent or urgent surgical exploration
• Neurologic: Operative therapy is indicated if conservative approach fails.
• • Supraclavicular decompression techniques may include anterior and middle scalenectomy, excision of a cervical rib if present and first rib resection.
  • A retrospective survey of 158 workman's compensation patients undergoing surgery for thoracic outlet syndrome (TOS) showed that 60% were still work-disabled 1 year after surgery.¹

Further Outpatient Care

• For most patients, conservative treatment is recommended. Stress avoidance, work simplification, and job site modification are recommended to avoid sustained contraction and repetitive or overhead work that exacerbate symptoms.
• Address myofascial or chronic pain elements through exercise programs, good posture, and self-management.
• Maximize the potential outlet space through a program of stretching and strengthening of the shoulder-elevating mechanism.
• • Trapezius and rhomboid strengthening (eg, shoulder shrugs and bilateral shoulder retraction while standing or lying prone)
  • Shoulder mobilization (eg, hand circles and standing corner pushups)
  • Postural exercises (eg, cervical and lumbar spine extension)

In/Out Patient Meds

• Coumadin: Anticoagulate for a minimum of 3 months for vascular TOS.
• Analgesics are seldom helpful except to assist in the institution of a progressive exercise program.
• Tricyclic antidepressants: A short-monitored course may be helpful if the time course and symptoms suggest a protracted pain syndrome.

Transfer

• Vascular - For definitive diagnosis and treatment if unavailable at current institution

Complications

• Neurologic - Chronic pain
• Arterial
• • Thrombosis
  • Thromboembolism
  • Acute ischemia
  • Poststenotic aneurysm formation
• Venous - Thrombosis

Prognosis

• Neurologic TOS is generally neither progressive nor likely to resolve spontaneously.
• Arterial or venous TOS usually results in a good outcome with adequate treatment.

REFERENCES

Section 9 of 9

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• References

1. Franklin GM, Fulton-Kehoe D, Bradley C, Smith-Weller T. Outcome of surgery for thoracic outlet syndrome in Washington state workers' compensation. Neurology. Mar 28 2000;54(6):1252-7. [Medline].
2. Aufderheide TP. Peripheral arteriovascular disease. Emerg Med: Concepts and Clinical Practice. 1998;2:1844-7.
3. Barkhordarian S. First rib resection in thoracic outlet syndrome. J Hand Surg [Am]. Apr 2007;32(4):565-70. [Medline].
4. Demondion X, Herbinet P, Van Sint Jan S, Boutry N, Chantelot C, Cotten A. Imaging assessment of thoracic outlet syndrome. Radiographics. Nov-Dec 2006;26(6):1735-50. [Medline].
5. Hood DB, Kuehne J, Yellin AE, Weaver FA. Vascular complications of thoracic outlet syndrome. Am Surg. Oct 1997;63(10):913-7. [Medline].
6. Huang JH, Zager EL. Thoracic outlet syndrome. Neurosurgery. Oct 2004;55(4):897-902; discussion 902-3. [Medline].
7. Oates SD, Daley RA. Thoracic outlet syndrome. Hand Clin. Nov 1996;12(4):705-18. [Medline].
8. Plewa MC, Delinger M. The false-positive rate of thoracic outlet syndrome shoulder maneuvers in healthy subjects. Acad Emerg Med. Apr 1998;5(4):337-42. [Medline].
9. Sanders RJ, Hammond SL, Rao NM. Diagnosis of thoracic outlet syndrome. J Vasc Surg. Sep 2007;46(3):601-4. [Medline].
10. Weber RJ, Lebduskin S. Rehabilitation issues in plexopathies. Phys Med Rehabil. 1988;996-8.

Article Last Updated: Feb 4, 2008