Thoracic outlet syndrome (TOS) describes a group of disorders involving compression of the nerves or blood vessels between the muscles of the neck and shoulder or between the first rib and collarbone (clavicle). This area is known as the thoracic outlet.
TOS often afflicts otherwise healthy, young, active individuals and symptoms are specific to nerve compression (neurogenic or NTOS), arterial compression (ATOS) or venous compression (VTOS).
Neurogenic TOS (NTOS)
This is the most common form of TOS and is due to compression of the nerves between the first rib, collarbone (clavicle) and scalene muscles. NTOS can result from a combination of a congenitally narrow thoracic outlet with trauma (for example, falls, motor vehicle accidents, first rib fractures) or repetitive trauma from work-related activity (for example, typing, administrative work or manual labor) or recreational activities (baseball, football, swimming, volleyball). Some patients are born with an extra cervical rib or bands of muscle which can further narrow the thoracic outlet and result in significant symptoms due to nerve compression.
Signs and Symptoms of NTOS
- Pain, numbness and tingling, weakness, discoloration, temperature changes in the arm, hand and fingers, and the forearm.
- Pain and tingling in the surrounding areas such as the base of the neck, chest wall, axilla (armpit), breast, upper back and head.
- Worsening of the above symptoms with the arm overhead (for example, brushing your hair) or with the arm dangling (for example, carrying heavy objects).
Diagnosis of NTOS
There is no definitive test to diagnosis NTOS. However, there are tests that are useful to rule out other conditions that may cause similar symptoms. These include:
- Electromyography (EMG) to evaluate for peripheral nerve entrapment.
- MRI to evaluate for cervical spine disease (e.g., cervical pinched nerve) or intrinsic shoulder disease (for example, torn rotator cuff).
- X-ray of the cervical spine to evaluate for a cervical rib.
Treatment of NTOS
The initial treatment includes a course of physical and occupational therapy focused on improving flexibility and to relieve tension and discomfort. If patients do not improve with therapy, thoracic outlet decompression is recommended. This involves removal of the first rib, surrounding muscle and scar tissue around the jugular and subclavian veins.
Following surgery, patients have a short inpatient hospital stay and then are discharged home, active and able to perform daily activities. During the next few months, a comprehensive physical and occupational therapy program allows patients to resume unrestricted activity. Patients follow a pre-set medication taper regimen so they are off all post-operative medications by six months.
Venous TOS (VTOS)
This is the second most common form of TOS and is due to compression of the subclavian vein between the collarbone (clavicle), first rib, subclavius muscle and the costoclavicular ligament (a ligament located in the upper chest in the area of the first rib and the collarbone). VTOS can result from a combination of a congenitally costoclavicular space with frequent, repetitive overhead activity that results in compression of the subclavian vein with progressive injury and thrombosis (clotting).
Signs and Symptoms of VTOS
- Patients may have some symptoms that are similar to NTOS.
- If the vein clots off (thromboses), patients will have a blue, swollen arm with significant discomfort.
- Patients with VTOS with a vein that has not thrombosed typically have arm swelling, fullness, heaviness, aching and a change in color with overhead activity.
Diagnosis of VTOS
The diagnosis of VTOS is supported by the following studies:
- Dynamic CT venogram/MR venogram: These non-invasive studies look at compression and obstruction of the subclavian vein (with the patient's arm in a neutral position and elevated). If the vein is clotted or becomes occluded with overhead activity, this supports the diagnosis.
- Venogram with possible lysis (a procedure in which clot-dissolving drugs are delivered to the site of a clot through a catheter): In patients with a clotted subclavian vein, this study allows for the removal of a clot and confirmation of the diagnosis.
Treatment of VTOS
If the vein is clotted, patients typically undergo a clot-dissolving procedure to remove the vein obstruction and a workup to confirm the diagnosis. Occasionally, blood tests are required to rule out other causes of clotting. Following restoration of blood flow, surgery is performed in 2-6 weeks depending on results of the venogram. Surgery includes a complete anterior and middle scalenectomy, resection of the entire first rib, removal of the subclavius muscle, intraoperative venography with reconstruction of the subclavian vein as needed.
Following surgery, patients have a short inpatient hospital stay and then are discharged home, active and able to perform daily activities. During the next few months, a comprehensive physical and occupational therapy program to allow patients to resume unrestricted activity. Patients follow a pre-set medication taper regimen so that patients are off all post-operative medications by six months.
Arterial TOS (ATOS)
This is the least common form of TOS and is due to compression of the subclavian artery between the first rib, collarbone (clavicle) and scalene muscles. Patients with ATOS can have atypical bands of muscle or a cervical rib that cause significant compression and injury to the subclavian artery. ATOS results from repetitive injury to the subclavian artery from anatomic compression that can result in narrowing (stenosis) of the artery, an aneurysm or formation of a clot that can embolize distally to the arm, forearm, hand or brain.
Signs and Symptoms of ATOS
Patients may experience symptoms that are similar to NTOS. They may also experience:
- A pulsating mass above the collarbone.
- Exercise-induced arm discomfort resulting from insufficient blood flow to the arm.
- Pain, numbness, tingling, cold sensation, pale/mottled hand or fingers with black spots, fingertip ulceration or gangrene.
Diagnosis of ATOS
The diagnosis of ATOS is supported by:
- Dynamic CT/MR Arteriogram: These are non-invasive studies that look at compression and patency of the subclavian artery while the arm is in a neutral position and elevated.
- Arteriogram with possible lysis: In patients with a clotted subclavian artery, this study allows for removal of clot and confirmation of the diagnosis.
Treatment of ATOS
Patients who present with acute/subacute upper extremity ischemia will need restoration of blood flow through lysis or through open surgery followed by a thoracic outlet decompression with a complete anterior and middle scalenectomy, resection of the entire first rib and possible arterial reconstruction. Patients with an incidentally found pulsating mass, a subclavian aneurysm or arm claudication will need a thoracic outlet decompression and possible arterial reconstruction.
Following surgery, patients have an inpatient hospital stay and then are discharged home, active and able to perform daily activities. During the next few months, a comprehensive physical and occupational therapy program allows patients to resume unrestricted activity. Patients follow a pre-set medication taper regimen such that patients are off all post-operative medications by six months.
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