Definition
A.Thoracic outlet syndrome (TOS) is a constellation of signs and symptoms that arise from compression of the neurovascular bundle just above the first rib and behind the clavicle, within the confined space of the thoracic outlet.
Incidence
A.TOS is uncommon and its true incidence is unknown.
B.Most patients are 20 to 50 years old, less than 5% are teenagers, and 10% are older than 50.
C.70% are female.
Pathogenesis
A.Neurogenic (nTOS) arises from brachial plexus compression.
1.It accounts for more than 95% of TOS cases.
2.Associated with developmental anomalies of the thoracic outlet and fibrosis of the scalene muscle.
3.Most common causes are hyperextension neck trauma (motor vehicle accident whiplash) and repetitive stress injuries.
B.Venous (vTOS) arises from subclavian vein compression.
1.It accounts for 3% of TOS cases.
2.Often a result of developmental anomalies of the costoclavicular space and repetitive arm activities.
3.In vTOS a focal area of scarred subclavian intima narrows the lumen. Thrombus is the final event that occludes the vein.
4.Typically asymptomatic until a venous thrombolytic event occurs.
C.Arterial (aTOS) arises from subclavian artery compression.
1.It accounts for 1% of TOS cases.
2.Almost always associated with a cervical rib or anomalous rib.
3.aTOS subclavian artery stenosis is accompanied by poststenotic dilatation that gives the appearance of an aneurysm. Thrombus forms in the dilatation.
4.Usually asymptomatic until the arterial emboli dislodges.
Predisposing Factors
A.Cervical rib or anomalous rib.
B.Congenital cervical fibrocartilaginous band associated with an incomplete cervical rib.
C.Muscular anomalies.
D.Chronic inflammatory change due to trauma.
E.Fractured first rib or clavicle.
F.Neck mass, for example, goiter, apical lung cancers, thyroid cancers, lymphoma.
G.Repetitive occupational overhead arm movements (e.g., box stacking), or sporting movements (e.g., pitching, swimming).
Subjective Data
A.Common complaints/symptoms.
1.Neurogenic TOS: Pain, dysesthesia, numbness, and weakness, which may not be localized in specific nerve distribution. Symptoms are reproducibly aggravated by elevation or sustained use of the arms or hands.
2.Venous TOS: Pain, cyanosis, edema. Paresthesia in the fingers is typically from swelling in the hand rather than nerve compression. Collateral venous patterning over the ipsilateral shoulder, neck, and chest wall indicates compensatory superficial venous flow from subclavian vein stenosis or occlusion.
3.Arterial TOS: Pain, pallor, paresthesia, coldness to hand. Symptoms develop spontaneously unrelated to work or trauma.
B.Common/typical.
1.Common causes of TOS include physical trauma from car accidents, sports, or repetitive injuries.
2.Sometimes having an anatomical defect such as an extra rib can cause this.
3.Patients may complain of numbness or tingling in their arm or fingers and have a weak grip.
C.Family and social history.
1.Elicit onset, duration, location, intensity, aggravators, and relievers of symptoms.
2.Ask about occipital headaches and pain over the trapezius, neck, chest, and shoulder. (Patients with symptoms confined to the forearm and hand are more likely to have carpal or cubital tunnel syndrome, not nTOS).
3.Enquire about any history of neck trauma (e.g., whiplash, clavicle fracture, fall on slippery surface, or tripping down stairs).
4.Enquire about occupational and recreational history of repetitive stress injury (e.g., hours on keyboards, assembly lines).
5.Rule out any secondary causes of upper extremity deep vein thrombosis or arterial thrombosis such as central venous catheters, pacemakers, or peripheral or coronary catheterization.
D.Review of systems.
1.Musculoskeletal: Ask about arm pain or swelling.
2.Cardiovascular: Ask about cold fingers.
3.Dermatology: Ask about any changes in skin color such as lack of color or bluish discoloration.
4.Neurology: Ask about numbness, tingling, or weakness of extremity.
Physical Examination
A.Perform a standard neurological test.
B.Take blood pressure in both arms. Lower systolic pressure in the affected arm may suggest aTOS.
C.Inspect.
1.Neck and supraclavicular area for pulsatile and non-pulsatile mass.
2.Hands and fingers: Swelling and cyanosis (vTOS), pale, cold, ischaemic changes (aTOS).
3.Skin overlying the ipsilateral shoulder, neck and chest wall for collateral venous patterning (vTOS).
D.Auscultate.
1.Heart to listen for arrhythmias, gallops, and murmurs.
2.Supraclavicular and infraclavicular fossa to listen for bruits or a thrill (aTOS).
E.Palpate.
1.Carotid and upper extremity pulses. Reduced or absent (aTOS).
2.Palpate scalene muscle to assess for tenderness (nTOS).
F.Perform provocative maneuvers.
1.Adson test.
a.Palpate the radial pulse and then move the patient’s upper extremity into an extended, abducted, and externally rotated position.
b.Patient then rotates and laterally flexes the neck to the ipislateral side while inhaling deeply.
c.A positive test results in reduction or obliteration of the radial pulse.
2.Elevated arm stress test (EAST) or Roos test.
a.Patient seated with arms abducted at 90° in external rotation, elbows flexed to 90°, head in neutral position.
b.Patient opens and closes hands.
c.The test has a high negative predictive value for nTOS if the patient performs the maneuver for 3 minutes.
Diagnostic Tests
A.The predominant clinical signs and symptoms direct the nature of further evaluation depending on the type of TOS.
1.Cervical spine x-ray: Identify bony abnormalities such as cervical ribs, anomalous ribs, or rib/clavicular fracture calluses.
2.Ultrasound: The initial imaging test to evaluate aTOS or vTOS. Provocative shoulder/arm maneuvers are performed under ultrasound.
3.Cross sectional imaging (CT or MR) and/or electromyography is best reserved for TOS specialists.
4.Hematologic evaluation: There are no specific blood tests for TOS. However, hematologic tests are helpful in ruling out other causes. See the “Diagnostic Test section
Upper Extremity Arterial Disease.”
Differential Diagnosis
A.Neurogenic TOS.
1.Carpal tunnel syndrome.
2.Ulnar nerve compression.
3.Rotator cuff tendinitis.
4.Neck strain/sprain.
5.Fibromyositis.
6.Cervical disc disease.
7.Cervical arthritis.
8.Brachial plexus injury.
B.Arterial TOS.
1.Embolization from other sources.
2.Vasculitis.
3.Radiation arteritis.
4.Connective tissue disorders.
5.Arterial dissection.
6.Atherosclerotic upper extremity disease.
7.Thromboangiitis obliterans.
8.Traumatic.
C.Venous TOS.
1.Acute thrombosis.
2.Lymphedema.
3.Rheumatologic disorders.
4.Cellulitis and allergic reactions.
5.Metabolic or global causes of limb swelling such as heart failure or myxedema.
Evaluation and Management Plan
A.General plan.
1.Treatment is indicated only for symptomatic patients. Having a cervical rib or other rib anomaly does not indicate a need to intervene.
2.Prevention and rehabilitation: Minimizing work-related overuse syndromes. Input from physical therapists.
3.Thrombolysis.
4.Severe arterial ischemia usually requires surgical embolectomy (with or without intraoperative thrombolysis).
5.Thoracic outlet decompression.
B.Patient/family teaching points.
1.Patients need to avoid repetitive movements and heavy lifting.
2.Diet and exercise can improve symptoms as well.
3.Stretching daily can keep muscles strong and prevent increased pressure on the thoracic outlet.
C.Pharmacotherapy.
1.Medical therapy: Interscalene injection of anesthetic agents, steroids, or botulinum toxin type A.
2.Anticoagulation.
D.Discharge instructions.
1.Patients should follow-up with their primary care provider.
2.Surgery may be indicated if medical treatment and physical therapy are not effective.
3.Untreated symptoms can lead to permanent nerve damage, so patients should report any worsening symptoms.
Follow-Up
A.As guided by appropriate specialist services (neurology, vascular, or general surgery).
Consultation/Referral
A.Acute ischemia: For hospital admission, seek vascular consult.
B.Non-acute, progressive symptoms referral to TOS specialist.
1.Such as complaints of shoulder, neck, head, chest, and arm problems with activity, elevation, or dangling; with supraclavicular or intraclavicular tenderness, and the absence of obvious cervical disc, rotator cuff, or carpal tunnel pathology.