Fig. 28.1
Anatomy of the thoracic outlet
Chronic compression of the venous system at the thoracic outlet is thought to lead to cyclical inflammation and quiescence. This eventually can generate endothelial injury and perivenous fibrosis which then prompts stasis and thrombosis of the axillo-subclavian vein [2].
Venous thoracic outlet syndrome must be differentiated from secondary venous thrombosis . Secondary upper-extremity deep venous thrombosis (DVT), an increasing problem, occurs in association with intravenous catheters for dialysis, chemotherapy, central intravenous access, and bone marrow transplantation.
Epidemiology
The true incidence of all thoracic outlet syndrome (including arterial and neurogenic) is debated. Venous TOS generally comprises 3–5% of all thoracic outlet cases. Primary upper-extremity DVT occurs in 2/100,000 individuals [3].
Clinical Presentation
Patients with venous thoracic outlet syndrome most commonly present with thrombosis, although some with McCleary syndrome (compression without thrombosis) may simply complain of intermittent swelling and color changes which resolve with adduction. Venous thrombosis can be occlusive or partially obstructive, acute, or chronic. The affected upper extremity can become suddenly blue-purple or even red and markedly edematous in the acute process. These patients become alarmed and will frequently present to the emergency room. Chronically, patients may be seen in the office with swelling that does not seem to resolve. They will often exhibit signs of collateralization with dilated superficial veins over the neck, chest, shoulder, back, and neck (Fig. 28.2). Dull aching or heaviness in the recumbent position is customary.
Fig. 28.2
Venogram showing extensive superficial collateralization
Venous TOS is regularly associated with repetitive upper-extremity activity and trauma. Patients who are athletes or professionally participate in arm motion can develop substantial muscle mass of the shoulder and the scalene triangle. Because of this, vTOS can present in adolescents [4].
Diagnosis
Diagnosing vTOS is a combination of clinical presentation, imaging, and ruling out other causes. Patients with unprovoked upper-extremity DVT need to be evaluated for an underlying hematologic etiology including oncological as well as hypercoagulable conditions. Secondary thrombosis with chronic indwelling catheters or pacemakers occurs more frequently than vTOS.
Maneuvers
Many physical exam maneuvers have been employed in the diagnosis of TOS. These are noninvasive, free, and performed in the office. They are more directed at the arterial and neurogenic components of the thoracic outlet syndrome ; however, they remain an important part of the overall evaluation. Because some patients can have compression of all three elements of TOS, these exercises should be completed for all patients being considered for TOS as some patients will have mixed components. The Adson test is most popular and utilized maneuver. The patient is requested to take a deep breath, rotate, and extend their head toward the unaffected side. The affected arm is then abducted with the elbow flexed while palpating the radial pulse. A positive test will obliterate the ipsilateral pulse. One should be cautious as the Adson test can produce false positives in many cases. The elevated arm stress test (EAST) or Roos Test is more sensitive. The patient is asked to abduct both shoulders to 90° again with the elbows flexed. With the hands facing forward, they alternately open/close their hands for a period of 3 min. A positive test occurs when this induces or exacerbates their symptoms.
Imaging
Routine imaging to diagnose vTOS primarily consists of ultrasound. A complete evaluation by duplex ultrasound is essential, using both grayscale and Doppler spectral waveform analysis. Maneuvers by abducting and adducting can be helpful although many ultrasonographers are hesitant in the setting of acute upper-extremity DVT for fear of clot embolization. Dampening of the waveform and marked decrease in velocities in the abducted position are nearly always present in vTOS. The presence and severity of venous thrombosis are also important to document. Sonographic imaging has been found accurate in the diagnosis of upper-extremity DVT with a sensitivity of 78–100% and a specificity of 82–100% [5].
Magnetic resonance venography (MRV) and computed tomographic venography (CTV) have been utilized to diagnose vTOS with increasing frequency. Results have shown high concordance with duplex ultrasound, but the cost for these tests can be unnecessarily burdensome in acute vTOS. They may have more of a role in chronic cases where extensive collaterals may affect the approach for surgical treatment.
Invasive venography has traditionally been the “gold standard” in diagnosis; however, catheter-based imaging is generally reserved for patients who need an initial intervention such as thrombolysis. Post-resection venography has become routine (see Treatment).
Treatment
Initial therapy for venous thoracic outlet syndrome is anticoagulation and arm elevation; however, definitive treatment remains surgical. Recurrent thrombosis without surgical decompression can occur in up to 70% of patients [6]. Additionally, 40% of patients treated with thrombolysis and anticoagulation alone will eventually undergo rib resection because of symptom recurrence [7]. To date, first rib resection and anterior scalenectomy (FRRS) is the standard of care.
Patients will naturally present in various stages of chronicity or even treatment. Once the diagnosis is reached, first rib resection and anterior scalenectomy for decompression should be scheduled. The sooner patients can be decompressed, the sooner they may come off anticoagulation. Our routine is to hold anticoagulation on the day of surgery and restart it at postoperative day 3. The patient then returns for a post-resection venogram at 2 weeks to assess for persistent stenosis and/or thrombosis (Fig. 28.3). Routine preoperative thrombolysis and venoplasty have not been shown to improve vein patency [8]. However, if the patient is found to be without stenosis or thrombosis at the postoperative venogram, anticoagulation may be safely stopped. This shortened length of anticoagulation is invaluable in the adolescent patient. Should a balloon venoplasty be required, anticoagulation should be continued for 1–2 months, and prior to stopping it, a duplex scan should demonstrate vein patency in abduction and adduction. If the vein cannot be reopened due to scarring or residual thrombus, anticoagulation is generally continued for an additional 6 months where >90% of the veins will reopen due to the removal of the extrinsic compression by the first rib, anterior scalene muscle, and subclavius tendon.
