Thoracic outlet syndrome (TOS) has been classified as neurogenic (95% of cases), venous (3- 5%), or arterial (1%). Patients commonly complain of arm pain. Presenting symptoms and predisposing conditions should be elucidated in the preop evaluation.
- Neurogenic TOS (nTOS): Patients have associated occipital headache, tension and tightness in the shoulders and interscapular area. Even though discomfort, numbness, and paresthesia can affect the forearm and the hand, they are unlikely to be confined to a single peripheral nerve distribution.
- Venous TOS (vTOS): Patients complain of swelling, heaviness, venous congestion, and sometimes cyanosis of the hand. These symptoms can develop acutely when associated with deep vein thrombosis (DVT) of the subclavian vein (in the setting of “effort thrombosis”) and occasionally can lead to pulmonary embolism (PE)
- Arterial TOS (aTOS): Patients present with hand ischemia related to distal microembolization, acute limb ischemia, or fullness in the supraclavicular area related to subclavian artery aneurysm formation. Hand coolness and discoloration has been also reported with nTOS because of compression of sympathetic nerve fibers causing Raynaud’s phenomenon.
A history of trauma to the area is common either as an accident (whiplash injury, clavicular fracture) or repetitive strain (computer typing for nTOS, baseball pitching for vTOS).
Activities involving abduction of the arm typically increase compression and exacerbate symptoms. TOS can also develop secondary to other diseases such as tumor compression or indwelling venous devices (tunneled catheters for dialysis, pacemaker leads) affecting typically an older group of patients.
A thorough exam of the upper extremities should focus on the presence of edema, discoloration, or coolness of the hand. Dilated superficial veins on anterior chest and shoulder regions may be present on the affected side of vTOS (Urschel sign). VTOS can very rarely present with venous gangrene (phlegmasia).
Neurological exam assesses the motor and sensory functions of the hand as well as any hypersensitivity in the arm. The neck, shoulders, and the area of the scalene triangle should be evaluated for spasm, stiffness, and trigger points that can reproduce the symptoms. The EAST (elevated arm stress test) test involves elevating the arms above the head and opening and closing the fists for 3 minutes. This maneuver compresses the neurovascular bundle and reproduces symptoms within 60 seconds in most patients especially with nTOS. The radial pulse is palpated, and intensity compared in both arms.
The Adson maneuver involves feeling the radial pulse in adduction and then raising the arm in 90 degrees abduction with rotating the head to the contralateral side and taking a deep breath. Loss of the pulse suggests compression of the artery in the thoracic outlet but is not sufficient to make the diagnosis as it can be anormal finding in patients without TOS.
Plain radiographs of the chest and neck can demonstrate bony anomalies associated with TOS such as cervical ribs. Venous and arterial duplex ultrasound with provocative maneuvers can demonstrate vascular compression and reproduce the pathophysiology. In patients with venous TOS, duplex ultrasound can also establish the diagnosis of acute axillosubclavian vein thrombosis.
Cross-sectional imaging with CTA or MRA should be performed with the arms at the sides and then in hyperabduction above the head to demonstrate vascular entrapment and define the relationship of the neurovascular structures and bony elements of the thoracic outlet. The extent of vascular thrombosis or aneurysmal degeneration can be assessed as well as the potential targets for reconstruction. Cross-sectional imaging can also rule out tumors or masses compressing the area and evaluate the cervical spine for degenerative disease. Although various ligamentous bands can contribute to the development of TOS, they are beyond the resolution of the current imaging modalities.
Catheter-based Angiography is used selectively in vascular TOS to assess arterial damage, embolization to the small arteries of the hand, or confirm diagnosis in conjunction with venous thrombolysis.
While advanced imaging is often enough for confirmation of diagnosis and operative planning in vascular TOS, the evaluation of patients with nTOS requires additional testing. Electromyography and nerve conduction studies are performed to rule out radiculopathy, peripheral nerve syndrome, or generalized myopathy. Several neurogenic and musculoskeletal conditions can mimic the symptoms of nTOS or simultaneously affect the patient. A scalene block is used to predict the potential response to surgical decompression. Relief of symptoms after injection of local anesthetic into the anterior scalene muscle can help select the patients that will benefit most from surgery.149
Medical Management and Lifestyle Changes
Physical therapy is recommended as first line treatment for patients with nTOS. A course of 4-8 weeks focused on stretching and relaxing the anterior scalene muscle can alleviate symptoms. Patients with mild nTOS could get sufficient relief with physical therapy combined with lifestyle changes minimizing activities that exacerbate symptoms.150 Patients presenting with arterial or venous thrombosis or embolization should be started on anticoagulation unless contraindicated. Patients with profound and limb-threatening ischemia to the upper extremity should undergo urgent revascularization.
Risk Stratification for Surgery
Most patients with TOS are relatively young, have limited comorbidities, and are considered good surgical candidates. Patients with more significant comorbidities may require a cardiac evaluation.
Some patients with end stage renal disease may require decompression for venous TOS, and will need a careful preoperative evaluation of comorbidities, and coordination of care with their nephrologist.
vTOS that is associated with subclavian vein thrombosis in patients with tunneled dialysis catheters or pacemaker leads typically affects an older group of patients who suffer from end-stage renal disease or advanced cardiac disease. The risks of surgery may outweigh the benefits in this group of patients.
Careful evaluation of the severity of patients’ symptom, goals of treatment, and alternative options should be considered.
Standard CBC, chemistry profile and coagulation profile are recommended before TOS surgery.
Preoperative Medication Adjustment
Patients on anticoagulation with heparin infusion should have the infusion held prior to procedure.
- Perioperative antibiotics: Prophylactic antibiotics for open procedures should be considered perioperatively as for any other surgery.
- Anticoagulation and its reversal: If patient is on oral anticoagulation preoperatively, then discontinue them as needed before the procedure to minimize bleeding complication. DOAC should be held for 48-72 hours before procedure. Warfarin should be discontinued 3-5 days in advance. Please consider bridging with parenteral anticoagulation (UFH or LMWH) in appropriate patients with high thrombosis risk.
- Nephropathy: Techniques to minimize contrast nephropathy for endovascular procedures in patients with CKD should be utilized. While many different agents have been studied with varying success, only fluid loading has been consistently reported to be associated with better renal outcomes. If there is no contraindication fluid administration pre, intra and post operatively is recommended. The issue to hold ACEs and ARBs is still not resolved and more research is needed.
- Allergy: Patients with allergy to intravenous iodinated contrast and scheduled for angiography should get premedication with prednisone 50 mg in 3 oral doses at 13 hours, 7 hours, and one hour prior to procedure, and Diphenhydramine 50mg one hour prior to procedure. Rescue dosing with IV solumedrol or Decadron can be used as needed. CO2 venography can also be considered as indicated
- ACE Inhibitors: If significant volume depletion is anticipated, it is suggested to hold ACE inhibitors and angiotensin receptor antagonists on the morning of surgery and restarting these agents after the procedure, once euvolemia has been achieved.
- Diabetes Mellitus: It is suggested to hold metformin at the time of administration of contrast material among patients with an eGFR of <60 mL/min or up to 48 hours before administration of contrast material if the eGFR is <45 mL/min and restarting no sooner than 48 hours after administration of contrast material as long as renal function has remained stable. Diabetic patients who receive intermediate or long-acting insulin should receive half the scheduled dose when NPO in preparation for surgery. Glycemic control should be considered per the current guidelines of the American Diabetes Association.18
Patients undergoing corrective surgery for thoracic outlet syndrome are often young and lack significant comorbidities.
The goal of surgery for TOS is to decompress the narrow thoracic outlet and remove all the structures contributing to compression of the neurovascular bundle. It consists of first rib resection with scalenotomy/scalenectomy. Some patients exhibit aberrant anatomy such as a cervical rib, scalenus minimus, and a variety of other fibromuscular bands that contribute to compression and should be removed concomitantly.151
a. Anesthesia Management
i) Anesthesia Techniques
- General endotracheal anesthesia is most commonly used. Placement of arterial pressure catheters or central venous catheters for monitoring should be decided on an individual patient basis depending on comorbidities in closed communication between the anesthesia and the surgical team.
- For a younger patient population, total intravenous anesthetic (TIVA) technique with propofol and minimizing opioids may be beneficial to prevent postoperative nausea and vomiting (PONV).
- Muscle relaxation should only be used if necessary and in close communication with the surgical team.
- Low cervical plexus block and intercostal nerve blocks by single shot or continuous infusion via catheter may help with intraoperative opioid minimization and postoperative pain control.
ii) Monitoring and Access
Standard monitoring SaO2, EKG and non-invasive blood pressure and temperature.
Invasive blood pressure monitoring is usually not necessary. Should existing cardiac comorbidities warrant the placement of an invasive arterial catheter, it should be placed on the contralateral side, as blood pressure measurements on the operative side may be interrupted by tourniquets or be inaccurate due to the existing compression.
IV access should be placed on the contralateral arm.
iii) Intraoperative Concerns
Intraoperative pneumothorax may occur.
d. General & Procedure-Specific Concerns
General intraoperative concerns: Skin preparation (CHG wipe timeout for three minutes to dry), Foley placed by trained staff, shaving performed with clippers, normothermia.
First rib resection:
- General anesthesia
- The placement of central intravenous lines and arterial line for hemodynamic monitoring is determined on a case-by-case basis depending on patient comorbidities and expected blood loss.
- Ipsilateral arm usually prepped sterile in the field to allow manipulation and optimization of exposure while avoiding tension on the brachial plexus for a long period of time.
- Perioperative antibiotics are weight based and initial dose should be administered prior to incision.
- Neuromuscular blocking agents should be avoided to allow intraoperative assessment of the brachial plexus
- If endovascular intervention or open venous reconstruction is performed, full dose anticoagulation is administered, and ACT is maintained above 200.
- A drain should be left in the surgical bed at the end of the operation to monitor for bleeding and lymphatic leak.
Steps Prior to Discharge
Open reconstructive surgery:
- An upright chest X-Ray is performed postoperatively.
- Incentive spirometer use is encouraged immediately after surgery and should be performed every hour.
- Mobilization out of bed is initiated within 24 hours after surgery with gradual increase in ambulation as tolerated.
- Diet can be resumed within 24 hours when patient is awake and there is no concern for aspiration.
- Glucose control.
- Foley catheter, although rarely needed in this patient population, is discontinued in 24- 48 hours after surgery when accurate assessment of urine output is not needed any more.
- Patients are admitted to a monitored unit and are assessed for hand neurological function, bleeding, and patency of flow when arterial reconstruction is performed.
- Drain output is monitored daily for early detection of bleeding or lymphatic leak.
- Central intravenous lines and arterial lines are removed when hemodynamic stability is established, and invasive monitoring is not warranted any more.
- Sterile occlusive intraoperative wound dressings are changed on postoperative day two.
- Perioperative antibiotics are discontinued in 24 hours.
- Anticoagulation for cases with vascular thrombosis should be started within 24-48 hours after surgery and when safe from bleeding standpoint
- Pain Control: Pain medications consists of intravenously narcotics initially and transitioned to oral narcotics as soon as patient is tolerating diet. Ketorolac and muscle relaxants are useful adjuncts to minimize discomfort.152
- Physical Therapy: Should be considered, especially for patients with neurogenic TOS who should continue with TOS therapy.
Steps After Discharge
- Heavy lifting or strenuous physical activity involving the arm should be avoided early after surgery, but a light range of motion exercises is encouraged as tolerated.
- Patients should be called within a week after discharge to ensure adequate recovery.
Office / Clinic Visit:
- Follow up office visit in 2-4 weeks after the procedure to assess clinical improvement (obtain duplex ultrasound for vTOS and aTOS)153
- Long-term follow up consists of yearly office visits for clinical assessment and ultrasound to document patency of the vascular reconstruction.
- Supervised, dedicated physical therapy for at least 6-8 weeks can start as soon as adequate wound healing is ensured.
- Narcotic medications are prescribed for pain control with goal to transition to over-the-counter pain medications (Acetaminophen or NSAIDs) as soon as tolerated.
- Anticoagulation is continued for at least four weeks post-surgery for patients with vascular thrombosis.
- The use of long-term medications can be coordinated with the patient’s primary care physician and can include the use of statins or a PCSK9 inhibitor in order to achieve optimal LDL control. In addition, anti-platelet agents, anti hypertensive agents, and agents for glycemic control should be prescribed, as indicated.