Overview
Definition:
Venous thoracic outlet syndrome (VTOS) is a condition characterized by compression of the subclavian vein, typically at the thoracic outlet, leading to venous obstruction
Scalenectomy involves the removal of the anterior and/or middle scalene muscles, and venolysis is the lysis of adhesions or fibrotic bands compressing the vein.
Epidemiology:
VTOS accounts for approximately 5-10% of all thoracic outlet syndrome cases
It most commonly affects young, athletic individuals, particularly those involved in repetitive overhead activities
The incidence is higher in males
Paget-Schroetter syndrome, a form of acute VTOS, is a significant subtype.
Clinical Significance:
Untreated VTOS can lead to debilitating symptoms, chronic venous insufficiency, post-thrombotic syndrome, pulmonary embolism (rare but life-threatening), and significant impact on an individual's quality of life and athletic performance
Prompt diagnosis and effective management are crucial for preventing long-term sequelae and optimizing outcomes.
Clinical Presentation
Symptoms:
Sudden onset of severe arm swelling (edema)
Heaviness or fullness in the affected arm
Cyanosis or discoloration of the arm
Aching pain in the shoulder, neck, and arm
Prominent collateral veins in the chest wall and shoulder
Dyspnea or chest pain in severe cases
Weakness or fatigue in the arm.
Signs:
Significant unilateral arm edema
Palpable venous distension in the arm and shoulder
Tenderness over the supraclavicular fossa
Impaired range of motion of the shoulder
Presence of collateral venous circulation on the chest wall
Absence of arterial pulse abnormalities unless there is concurrent arterial TOS.
Diagnostic Criteria:
Diagnosis is primarily clinical, supported by imaging
Criteria often include a history of repetitive overhead activities, characteristic symptoms, physical findings of venous obstruction, and exclusion of other causes of arm swelling
Imaging confirmation of venous compression or thrombosis is essential.
Diagnostic Approach
History Taking:
Detailed history of symptom onset and progression
Nature of activity precipitating symptoms (e.g., sports, occupation)
Presence of constitutional symptoms (fever, weight loss)
Previous history of venous thrombosis or clotting disorders
Family history of hypercoagulability
Medications (e.g., oral contraceptives).
Physical Examination:
Bilateral comparison of arm circumference and appearance
Palpation for tenderness and masses in the supraclavicular and axillary regions
Assess range of motion of the shoulder and neck
Examine for collateral venous development
Auscultate for bruits
Assess for neurological deficits (though less common in pure venous TOS).
Investigations:
Doppler ultrasonography: Initial modality to assess venous flow, identify thrombus, and evaluate compression with provocative maneuvers (e.g., arm abduction and external rotation)
Computed Tomography Angiography (CTA) or Magnetic Resonance Angiography (MRA): To delineate venous anatomy, assess the extent of compression, and identify fibrotic bands or anatomical abnormalities
Venography: Gold standard for visualizing venous anatomy and collateralization
often performed during intervention
Coagulation studies: To rule out hypercoagulable states.
Differential Diagnosis:
Deep vein thrombosis (DVT) of the upper extremity (non-TOS related)
Axillary-subclavian vein thrombosis from central venous catheter or pacemaker leads
Lymphedema
Cellulitis
Superior vena cava (SVC) syndrome
Peripheral arterial disease
Brachial plexus compression (neurologic TOS).
Management
Initial Management:
Anticoagulation: Initiation of therapeutic anticoagulation (e.g., unfractionated heparin followed by warfarin or direct oral anticoagulants) is crucial to manage acute thrombosis and prevent propagation
Arm elevation and pain control.
Medical Management:
Pharmacological therapy primarily involves anticoagulation to treat existing thrombus and prevent further clotting
Duration of anticoagulation is typically long-term, guided by risk factors and extent of thrombosis
Thrombolysis: May be considered for extensive acute thrombosis in select patients to rapidly restore venous patency and reduce post-thrombotic syndrome risk, often in conjunction with interventional radiology.
Surgical Management:
Surgical indications: Persistent or recurrent symptoms despite anticoagulation
failure of conservative management
significant anatomical compression identified on imaging
acute thrombosis in younger patients at high risk for post-thrombotic syndrome
Procedures: 1
First Rib Resection: Removal of the first rib to decompress the subclavian vein
2
Scalenectomy: Excision of the anterior and/or middle scalene muscles to release scalene muscle fibrosis and anterior muscle tension
3
Venolysis: Surgical division of fibrous bands or adhesions compressing the vein
Often combined with first rib resection
4
Vascular repair/reconstruction: If there is significant venous stenosis or damage, venous bypass or patch angioplasty may be required
5
Venous stenting: Placement of a self-expanding stent during venography to maintain venous patency, often performed concurrently with or after decompression.
Supportive Care:
Physical therapy post-surgery to restore shoulder range of motion and prevent stiffness
Graduated return to activity
Long-term anticoagulation management
Education on risk factor modification and symptom monitoring
Compression garment therapy for residual edema.
Complications
Early Complications:
Bleeding from anticoagulation or surgical site
Nerve injury (e.g., phrenic nerve, brachial plexus)
Pneumothorax from first rib resection
Vascular injury during dissection
Wound infection
Hematoma formation.
Late Complications:
Recurrent venous thrombosis
Post-thrombotic syndrome (chronic edema, pain, skin changes)
Persistent venous stenosis or re-occlusion
Thoracic outlet re-stenosis
Chronic pain
Shoulder dysfunction or stiffness
Pulmonary embolism (rare but serious).
Prevention Strategies:
Careful surgical technique with meticulous dissection
Appropriate patient selection for anticoagulation and surgical intervention
Optimal anticoagulation regimen and duration
Aggressive postoperative physiotherapy
Lifestyle modification to avoid aggravating activities
Early recognition and management of recurrent symptoms.
Prognosis
Factors Affecting Prognosis:
Timeliness of diagnosis and treatment
Extent of venous thrombosis
Presence of anatomical abnormalities
Patient's overall health and adherence to treatment
Success of surgical decompression and anticoagulation
Development of post-thrombotic syndrome.
Outcomes:
With appropriate management, including surgical decompression and anticoagulation, most patients can achieve symptom relief and return to functional status
However, a subset may develop chronic venous insufficiency or recurrent thrombosis
Long-term anticoagulation is often necessary
Recurrence rates vary but can be significant.
Follow Up:
Regular follow-up with vascular surgery is essential
This includes clinical assessment for recurrence of symptoms or signs of post-thrombotic syndrome
Periodic duplex ultrasound may be used to monitor venous patency, especially after stenting or bypass
Long-term anticoagulation monitoring is crucial if indicated
Patients should be educated on lifelong monitoring and avoiding precipitating activities.
Key Points
Exam Focus:
Paget-Schroetter syndrome is synonymous with effort-related acute upper extremity deep vein thrombosis, a common presentation of venous TOS
First rib resection and scalenectomy are the cornerstones of surgical decompression
Anticoagulation is mandatory for acute thrombosis
Venography with stenting is increasingly used for recalcitrant venous TOS.
Clinical Pearls:
Always consider venous TOS in young, athletic individuals with acute, unexplained upper extremity swelling
Provocative maneuvers on ultrasound are key
Differentiate from arterial TOS, which has distinct symptoms and management
Early surgical decompression can significantly improve outcomes and reduce the risk of post-thrombotic syndrome.
Common Mistakes:
Delaying anticoagulation in acute thrombosis
Failing to adequately decompress the thoracic outlet during surgery, leading to re-stenosis
Inadequate duration or intensity of anticoagulation
Overlooking anatomical variations that predispose to compression
Misdiagnosing venous TOS as muscular strain or other less severe conditions.