KEY-WORDS: Thoracic outlet syndrome

INTRODUCTION
CLINICAL
WORKUP
TREATMENT
MEDICATION
FOLLOW-UP
BIBLIOGRAPHY

.

INTRODUCTION

Background: Thoracic outlet syndrome refers to compression of the neurovascular structures at the superior aperture of the thorax. 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 effected. Most presentations to the emergency department are nonemergent and require only symptomatic treatment and referral.

Frequency:

Sex: The sex ratio varies depending on the type of thoracic outlet syndrome (e.g., neurologic, venous or arterial). Overall, the entity is approximately 3 times more common in women.

Age: The onset of symptoms usually occurs between the ages of 20 and 50 years.

• Neurological symptoms occur in 95% of cases. The lower 2 nerve roots, 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 patient with pain or numbness

• Loss of dexterity

• Cold intolerance

• Headache

• Venous: Pain

• Arterial:

• Pain

• Claudication

Physical: In the majority of cases, the physical examination is completely normal.

• 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 EAST (elevated arm stress test) is of debatable use, but may be the most reliable screening test. It evaluates all 3 types of thoracic outlet syndrome.

• 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 thoracic outlet syndrome 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 positive EAST test and the presence of a radial pulse are strong indicators of neurologic involvement of the brachial plexus.

• Supraclavicular tenderness

• Usually no evidence of muscle atrophy

• Paresthesias

• Weakness (usually subtle) of affected limb

• Venous:

• Edema

• Cyanosis

• Distended superficial veins of the shoulder and chest

• Arterial:

• Pallor and pulselessness

• Coolness on the affected side

• Lower blood pressure in affected arm (a reliable indicator of arterial involvement)

• Multiple small infarcts on hand and fingers (embolization)

Causes: There are 3 major causes: 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 first rib inferiorly accounts for the majority of neurologic and arterial thoracic outlet syndromes.

• Cervical ribs are found in the majority of arterial cases but rarely in venous and neurologic cases.

• Congenital fibromuscular bands (up to 80% of patients with neurologic thoracic outlet syndrome)

• Elongated transverse process of C7

• Trauma or Repetitive Activities:

• Motor vehicle accident hyperextension injury, with subsequent fibrosis and scarring

• Effort vein thrombosis (i.e. spontaneous thrombosis of the axillary veins following vigorous arm exertion)

• Musicians can be particularly susceptible owing to their need to maintain the shoulder in abduction or extension for long periods.
  
• Costoclavicular space: Between the first rib and the head of the clavicle

• With the rare exception of a vascular cause, the vast majority of ED presentations will not be 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 Radiograph:

• Cervical or first rib

• Clavicle deformity

• Pulmonary disease

• Pancoast tumor

• Color flow duplex scanning for suspected vascular thoracic outlet syndrome

• Arteriogram (indications):

• Evidence of peripheral emboli in the upper extremity

• Suspected subclavian stenosis or aneurysm (e.g., bruit or abnormal supraclavicular pulsation)

• Blood pressure differential greater than 20 mm Hg

• Obliteration of radial pulse during EAST test (elevated arm stress test)

• Venography (indications):

• Persistent or intermittent edema of the hand or arm

• Peripheral unilateral cyanosis

• Prominent venous pattern over the arm, shoulder or chest

• 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 emergency department.

• Nerve conduction evaluation via root stimulation and F wave is the best direct approach to evaluation of neurologic thoracic outlet syndrome.

• Electromyography (EMG) is unreliable and does not provide objective evidence of thoracic outlet syndrome.
  
• Cervical myelogram, CT or MRI for patients suspected of having cervical disk disease or spinal cord disease

• Vascular (arterial and venous):

• Immediate heparinization

• Vascular surgery consultation

• Color flow duplex scanning

• Angiography or venography

• Neurologic: Conservative outpatient physiotherapy

• 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 work up.

• 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 for failed conservative approach - more than 4 months): Supraclavicular decompression (anterior and middle scalenectomy, excision of a cervical rib if present and, occasionally, first rib resection)

Further Outpatient Care:

• Stress avoidance, work simplification and job site modification to avoid sustained contraction and repetitive or overhead work that exacerbates 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 (e.g., shoulder shrugs and bilateral shoulder retraction while standing or lying prone)

• Shoulder mobilization (e.g., hand circles and standing corner pushups)

• Postural exercises (e.g., cervical and lumbar spine extension)

In/Out Patient Meds:

• Coumadin: Anticoagulate for a minimum of 3 months for vascular thoracic outlet syndrome

• 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 thoracic outlet syndrome is generally neither progressive nor likely to resolve spontaneously.
  
• Arterial and venous thoracic outlet syndrome usually results in a good outcome with adequate treatment.
  

• Aufderheide TP : Peripheral arteriovascular disease. Emergency Medicine: Concepts and Clinical Practice 1998; 2: 1844-1847.
• Hood DB, Kuehne J, Yellin AE: Vascular complications of thoracic outlet syndrome. Am Surg 1997 Oct; 63(10): 913-7.
• Oates SD , Daley RA: Thoracic outlet syndrome. Hand Clin 1996 Nov; PT - REVIEW LITERATURE(4): 705-18.
• Plewa MC, Delinger M: The false-positive rate of thoracic outlet syndrome shoulder maneuvers in healthy subjects. Acad Emerg Med 1998 Apr; 5(4): 337-42.
• Weber RJ, Lebduskin S: Rehabilitation issues in plexopathies. Physical Medicine and Rehabilitation 1988; 996-998.