THORACIC OUTLET SYNDROME

Muhammad Imran Khan, MD • Najm Hasan Siddiqui, MD

 BASICS

DESCRIPTION

•  A constellation of symptoms that affects the head, neck, shoulders, and upper extremities caused by compression of the neurovascular structures (i.e., brachial plexus and subclavian vessels) at the thoracic outlet, specifically in the area superior to the 1st rib and posterior to the clavicle

•  Three forms of thoracic outlet syndrome (TOS) have been described: neurogenic, vascular (containing venous and arterial symptoms), and nonspecific (includes traumatic and secondary to certain provocative movements).

•  Synonym(s): scalenus anticus syndrome; cervical rib syndrome; costoclavicular syndrome

Pregnancy Considerations

Generalized tissue fluid accumulations and postural changes may aggravate symptoms.

EPIDEMIOLOGY

Incidence

•  Predominant age

–  Neurogenic type (95%): 20 to 60 years

–  Venous type (4%): 20 to 35 years

–  Arterial type (1%; atherosclerosis): young adult or >50 years

•  Predominant sex

–  Neurogenic type: female > male (3.5:1)

–  Venous type: male > female

–  Arterial type: male = female

•  No objective confirmatory tests are available to measure true incidence.

•  Estimated 3 to 8/1,000 cases for neurogenic type

•  Incidence of other TOS types is unclear.

ETIOLOGY AND PATHOPHYSIOLOGY

The interscalene triangle area is reduced in TOS and may become smaller during certain shoulder and arm movements. Fibrotic bands, cervical ribs, and muscle variations may further narrow the triangle. Trauma or provocative movements affecting the lower brachial plexus have strong implications in TOS pathogenesis.

•  Three known causes of TOS: anatomic, traumatic/repetitive movement activities, and neurovascular entrapment

–  Anatomic: Variations in the anatomy of the neck scalene muscles may be responsible for presentations of the neurologic type of TOS and may involve the superior border of the 1st rib. Cervical ribs also have been implicated as a cause of neurologic TOS, with subsequent neuronal fibrosing and degeneration associated with arterial hyalinization in the lower trunk of the brachial plexus. Fibrous bands to cervical ribs are often congenital.

–  Trauma or repetitive movement activities: Motor vehicle accidents with hyperextension injury and resulting fibrosis, including fibrous bands to the clavicle; musicians who maintain prolonged positions of shoulder abduction or extension may be at increased risk.

–  Neurovascular entrapment: occurring in the costoclavicular space between the 1st rib and the head of the clavicle

RISK FACTORS

•  Trauma, especially to the shoulder girdle

•  Presence of a cervical rib

•  Posttraumatic, exostosis of clavicle or 1st rib, postural abnormalities (e.g., drooping of shoulders, scoliosis), body building with increased muscular bulk in thoracic outlet area, rapid weight loss with vigorous physical exertion and/or exercise, pendulous breasts

•  Occupational exposure: computer users; musicians; repetitive work involving shoulders, arms, hands

•  Young, thin females with long necks and drooping shoulders

GENERAL PREVENTION

Consider observation or further evaluation in patients with cervical ribs.

COMMONLY ASSOCIATED CONDITIONS

•  Paget–von Schrötter syndrome: thrombosis of subclavian vein

•  Gilliatt-Sumner hand: neurogenic atrophy of abductor pollicis brevis

 DIAGNOSIS

HISTORY

•  Neurologic type, upper plexus (C4–C7)

–  Pain and paresthesias in head, neck, mandible, face, temporal area, upper back/chest, outer arm, and hand in a radial nerve distribution

–  Occipital and orbital headache

•  Neurologic type, lower plexus (C8–T1)

–  Pain and paresthesias in axilla, inner arm, and hand in an ulnar nerve distribution, often nocturnal

–  Hypothenar and interosseous muscle atrophy

•  Venous type: arm claudication, cyanosis, swelling, distended arm veins

•  Arterial type: digital vasospasm, thrombosis/embolism, aneurysm, gangrene

PHYSICAL EXAM

•  Positive Adson maneuver (head rotation to the affected side with cervical extension and then deep inhalation); test is positive if paresthesias occur or if radial pulse is not palpable during maneuver.

•  Tenderness to percussion or palpation of supraclavicular area

•  Worsening of symptoms with elevation of arm, overhead extension of arms, or with arms extended forward (e.g., driving a car, typing, carrying objects); prompt disappearance of symptoms with arm returning to neutral position

•  Morley test

–  Brachial plexus compression test in the supraclavicular area from the scalene triangle

–  Positive with reproduction of an aching sensation and typical localized paresthesia

•  Hyperabduction test: diminishment of radial pulse with elevation of arm above the head

•  Military maneuver (i.e., costoclavicular bracing): When patient elevates chin and pushes shoulders posteriorly in an extreme “at-attention” position, symptoms are provoked.

•  1-minute Roos test

–  A thoracic outlet shoulder girdle stress test

–  Shoulders and arms are braced in a 90-degree abducted and externally rotated position; patient is required to clench and relax fists repetitively for 1 minute.

–  A positive test reproduces the symptom.

DIFFERENTIAL DIAGNOSIS

•  Cervical disk or carpal tunnel syndrome

•  Orthopedic shoulder problems (shoulder strain, rotator cuff injury, tendonitis)

•  Cervical spondylitis

•  Ulnar nerve compression at elbow and hand

•  Multiple sclerosis

•  Spinal cord tumor/disease

•  Angina pectoris

•  Migraine

•  Complex regional pain syndromes

•  C3–C5 and C8 radiculopathies

DIAGNOSTIC TESTS & INTERPRETATION

Initial Tests (lab, imaging)

CBC, ESR, and C-reactive protein (CRP) determination may rule out underlying inflammatory conditions.

•  Radiograph (chest, C-spine, shoulders) (1)[C] may reveal elongated C7 transverse process or a cervical rib, Pancoast tumor, or healed clavicle fracture.

•  Nerve conduction studies and electromyography (EMG)

•  CT scan or MRI, although MRI is the method of choice when searching for nerve compression

•  Improved high-resolution MRN and tractography are valuable tools for identifying the source of nerve compression in patients with neurogenic TOS and can augment current diagnostic modalities for this syndrome (2)[B].

•  Contrast-enhanced 3D MRA using provocative arm positioning allows excellent imaging of the arteries and veins on both sides and thus provides a noninvasive imaging alternative to digital subtraction angiography in patients with suspected vascular TOS (3)[B].

•  Doppler and duplex US if vascular obstruction is suspected

•  Arteriogram and venogram have limited roles; useful when symptoms suggestive of arterial insufficiency or ischemia, or in planning surgical intervention (4)[C].

Diagnostic Procedures/Other

No indicated procedures; anesthetic anterior scalene block may relieve pressure by scalene muscles on the brachial plexus, making this type of block diagnostic and potentially therapeutic, but it poses the risk of procedural damage to the brachial plexus.

Test Interpretation

Systematic results of biopsy have not been reported. There is no indication for biopsy unless to investigate another underlying condition.

 TREATMENT

GENERAL MEASURES

•  Conservative management usually involves approaches to reduce and redistribute pressure and traction through the use of physiotherapy or prosthesis.

•  Interscalene injections of botulinum toxin have been shown to decrease symptoms of TOS (5)[C]. A single, CT-guided Botox injection into the anterior scalene muscle may offer an effective, minimally invasive treatment for NTOS (6)[A].

•  Physical therapy will develop strength in pectoral girdle muscles and achieve normal posture (1)[C].

•  Severe cases may use taping, adhesive elastic bandages, moist heat, TENS, or US but should not substitute active exercise and correction of posture and muscle imbalance (7)[B].

MEDICATION

•  No firm evidence exists for any approach to the four types of TOS.

•  Physical therapy is the first-line treatment (7)[B].

•  Anti-inflammatory (ibuprofen)

–  Adult dose: 400 to 800 mg PO q8h; not to exceed 3,200 mg/day

–  Pediatric dose

  <12 years: 10 mg/kg/dose every 6 to 8 hours

  >12 years: as in adults

–  Contraindications: documented hypersensitivity, active PUD, renal or hepatic impairment, recent use of anticoagulants, hemorrhagic conditions

•  Neuropathic pain: Tricyclic antidepressants, carbamazepine, gabapentin, phenytoin, pregabalin; muscle relaxants such as baclofen, metaxalone, or tizanidine may be helpful.

•  Severe pain: Consider opiates for brachial plexus nerve block, steroid injections.

ISSUES FOR REFERRAL

•  Neurologic, anesthesiologic, orthopedic, vascular surgery referral(s) may be indicated depending on the type of pathologic condition.

•  Physical and rehabilitation physicians

SURGERY/OTHER PROCEDURES

•  Operative if vascular involvement is present and/or loss of function or lifestyle occurs secondary to severity of symptoms and if conservative therapy fails after 2 to 3 months (1)[C]

•  Resection of 1st rib or cervical ribs via transaxillary (preferred with good to excellent outcome 80% of patients), supraclavicular (good to excellent outcome 80% of patients), posterior approaches (reserved for complicated TOS due to necessity of large muscle incision). Excellent results were seen in patients who underwent first rib resection in all three forms of TOS (8)[A].

•  Transaxillary 1st rib resection (TFRR) may provide better pain relief than supraclavicular neuroplasty of the brachial plexus (SNBP); although, overall, both treatment options have generally positive outcomes (9)[B].

•  Transaxillary approach provides a good exposure and cosmetics in patients with TOS. It should be considered as the gold standard in the management of TOS (10)[B].

•  Supraclavicular scalenectomy (11)[C]

•  Isolated pectoral minor tenotomy (PMT) is a low-risk outpatient procedure that is effective for the treatment of selected patients with disabling NTOS, with early outcomes similar to supraclavicular decompression + PMT (12)[A].

•  Excision of adhesive bands, anterior scalenectomy (13)[B]

ADMISSION, INPATIENT, AND NURSING CONSIDERATIONS

Conservative, outpatient, nonpharmacologic treatment is reasonable first-line therapy except in cases of thromboembolic phenomena and acute ischemia, symptoms of chronic vascular occlusion, stenosis, arterial dilatation, or progressive neurologic deficit (7)[B].

 ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Correct improper posture, practice proper posture, exercises to strengthen shoulder elevator and neck extensor muscles, stretching exercises for scalene muscles, support bra for women with pendulous breasts, breast reduction surgery in selected cases; sleep with arms below chest level, avoid/reduce prolonged hyperabduction.

Patient Monitoring

Office follow-up visits every 3 to 4 weeks

PATIENT EDUCATION

Physical therapy, postural exercises, ergonomic workstation

PROGNOSIS

Follow-up from surgery at mean of 7.5 years showed that functional results were excellent, good, fair, and poor in 87 (49.4%), 61 (34.6%), 14 (8%), and 14 (8%) procedures, respectively (14).

Durable long-term functional outcomes can be achieved predicated on a highly selective approach to the surgical management of patients with TOS. A majority of operated patients will not require adjunctive procedures or chronic narcotic use (15).

COMPLICATIONS

•  Postoperative shoulder, arm, hand pain, and paresthesias in 10%

•  Patients who will have symptomatic recurrences at 1 month to 7 years postoperatively (usually within 3 months): 1.5–2%

•  Patients who will have brachial plexus injury, probably due to intraoperative traction: 0.5–1%

•  Reoperation is indicated for symptomatic recurrence with long posterior remnant of 1st rib (posterior approach) or with disrupted fibrous adhesions (transaxillary approach).

•  Venous obstruction or arterial emboli; usually responds to thrombolytics

REFERENCES

  1.  Huang JH, Zager EL. Thoracic outlet syndrome. Neurosurgery. 2004;55(4):897–902.

  2.  Magill ST, Brus-Ramer M, Weinstein PR, et al. Neurogenic thoracic outlet syndrome: current diagnostic criteria and advances in MRI diagnostics. Neurosurg Focus. 2015;39(3):E7.

  3.  Ersoy H, Steigner ML, Coyner KB, et al. Vascular thoracic outlet syndrome: protocol design and diagnostic value of contrast-enhanced 3D MR angiography and equilibrium phase imaging on 1.5- and 3-T MRI scanners. AJR Am J Roentgenol. 2012;198(5):1180–1187.

  4.  Sanders RJ, Hammond SL, Rao NM. Diagnosis of thoracic outlet syndrome. J Vasc Surg. 2007;46(3):601–604.

  5.  Lee GW, Kwon YH, Jeong JH, et al. The efficacy of scalene injection in thoracic outlet syndrome. J Korean Neurosurg Soc. 2011;50(1):36–39.

  6.  Christo PJ, Christo DK, Carinci AJ, et al. Single CT-guided chemodenervation of the anterior scalene muscle with botulinum toxin for neurogenic thoracic outlet syndrome. Pain Med. 2010;11(4):504–511.

  7.  Vanti C, Natalini L, Romeo A, et al. Conservative treatment of thoracic outlet syndrome. A review of the literature. Eura Medicophys. 2007;43(1):55–70.

  8.  Orlando MS, Likes KC, Mirza S, et al. A decade of excellent outcomes after surgical intervention in 538 patients with thoracic outlet syndrome. J Am Coll Surg. 2015;220(5):934–939.

  9.  Sheth RN, Campbell JN. Surgical treatment of thoracic outlet syndrome: a randomized trial comparing two operations. J Neurosurg Spine. 2005;3(5):355–363.

10.  Lattoo MR, Dar AM, Wani ML, et al. Outcome of trans-axillary approach for surgical decompression of thoracic outlet: a retrospective study in a tertiary care hospital. Oman Med J. 2014;29(3):214–216.

11.  Glynn RW, Tawfick W, Elsafty Z, et al. Supraclavicular scalenectomy for thoracic outlet syndrome—functional outcomes assessed using the DASH scoring system. Vasc Endovascular Surg. 2012;46(2):157–162.

12.  Vemuri C, Wittenberg AM, Caputo FJ, et al. Early effectiveness of isolated pectoralis minor tenotomy in selected patients with neurogenic thoracic outlet syndrome. J Vasc Surg. 2013;57(5):1345–1352.

13.  Urschel HC, Kourlis H. Thoracic outlet syndrome: a 50-year experience at Baylor University Medical Center. Proc (Bayl Univ Med Cent). 2007;20(2):125–135.

14.  Degeorges R, Reynaud C, Becquemin JP. Thoracic outlet syndrome surgery: long-term functional results. Ann Vasc Surg. 2004;18(5):558–565.

15.  Scali S, Stone D, Bjerke A, et al. Long-term functional results for the surgical management of neurogenic thoracic outlet syndrome. Vasc Endovascular Surg. 2010;44(7):550–555.

ADDITIONAL READING

Povlsen B, Belzberg A, Hansson T, et al. Treatment for thoracic outlet syndrome. Cochrane Database Syst Rev. 2010;(1):CD007218.

 CODES

ICD10

G54.0 Brachial plexus disorders

CLINICAL PEARLS

•  Consider breast reduction for patients with pendulous breasts.

•  Avoid opiate dependence.

•  Consider pain clinic referral if there are nonsurgical causes.