# Upper Extremity DVT and Thoracic Outlet Syndrome

## Overview

Upper extremity deep vein thrombosis (UEDVT) represents approximately 5-10% of all deep vein thrombosis cases. It can be classified into primary and secondary forms. Primary UEDVT, also known as Paget-Schroetter syndrome, is an effort-related thrombosis that typically occurs in young, active individuals due to compression at the thoracic outlet. Secondary UEDVT arises from factors such as central venous catheters, malignancy, or underlying hypercoagulable states. Thoracic outlet syndrome (TOS) refers to the compression of the neurovascular bundle as it passes through the thoracic outlet and is categorized into venous, arterial, or neurogenic types based on the structures involved.

## Anatomy of the Thoracic Outlet

### Boundaries

The thoracic outlet consists of three anatomical compartments through which the neurovascular bundle passes. The first is the interscalene triangle, bordered anteriorly by the anterior scalene muscle, posteriorly by the middle scalene muscle, and inferiorly by the first rib. This space contains the subclavian artery and the brachial plexus. The second compartment is the costoclavicular space, located between the clavicle superiorly and the first rib inferiorly; it contains the subclavian vein. The third compartment is the subcoracoid or pectoralis minor space, situated beneath the pectoralis minor tendon at the coracoid process.

### Key Structures

The subclavian vein travels anterior to the anterior scalene muscle through the costoclavicular space, whereas the subclavian artery passes posterior to the anterior scalene within the interscalene triangle. The brachial plexus, formed by the C5 to T1 nerve roots, also traverses the interscalene triangle alongside the artery. Occasionally, a cervical rib—present in about 0.5-1% of the population—may be found; this is an extra rib arising from the C7 vertebra, either rudimentary or complete. Additionally, anomalous fibrous bands may compress neural and vascular structures within the thoracic outlet.

<image>Anatomical illustration of the thoracic outlet showing the interscalene triangle, costoclavicular space, and relationships of the subclavian artery, subclavian vein, brachial plexus, anterior and middle scalene muscles, first rib, and clavicle</image>

## Venous Thoracic Outlet Syndrome (Paget-Schroetter Syndrome)

### Pathophysiology

In venous thoracic outlet syndrome, the subclavian vein becomes compressed within the costoclavicular space, which is bounded by the clavicle, first rib, and the subclavius and anterior scalene muscles. Repetitive overhead arm movements, common in athletes and manual laborers, cause endothelial injury to the vein. Chronic compression leads to intimal fibrosis and eventually thrombosis. This condition is often termed "effort thrombosis," describing an acute thrombosis of the subclavian-axillary vein triggered by vigorous upper extremity activity.

### Clinical Presentation

Patients typically present with sudden onset of arm swelling, a sensation of heaviness, cyanosis, and pain following strenuous activity. The dominant arm is most commonly affected, especially in young, muscular individuals such as swimmers, pitchers, and weightlifters. Prominent venous collaterals may be visible across the shoulder and chest wall. Some patients report prior episodes of arm heaviness or positional swelling without thrombosis, a phenomenon known as McCleery syndrome, which reflects intermittent venous compression.

### Diagnosis

Duplex ultrasound is the initial imaging modality, demonstrating thrombosis of the subclavian or axillary vein, although its utility can be limited by acoustic shadowing from the clavicle. Contrast venography is the gold standard for confirming the location and extent of thrombus and visualizing collateral vessels. Positional venography performed with the arm abducted and externally rotated can reveal extrinsic venous compression. CT or MR venography further delineates the anatomical relationships, identifies cervical ribs, and assesses compression relative to the first rib.

### Treatment Algorithm

Management begins with immediate systemic anticoagulation, typically using heparin. Catheter-directed thrombolysis with agents such as alteplase is recommended within two weeks of symptom onset, delivered via brachial or basilic vein access. Serial venography monitors thrombolysis progress, which usually lasts 12 to 48 hours. After thrombolysis, venography with provocative arm positioning assesses residual extrinsic compression. Definitive treatment involves first rib resection to decompress the thoracic outlet. The timing of surgery is debated; early intervention within 2-4 weeks may prevent rethrombosis, while delayed surgery at 6-12 weeks allows for reduced inflammation and easier dissection. Post-decompression venography evaluates for residual stenosis, which can be treated with balloon angioplasty if present. Venous stenting is generally avoided due to the high compressive forces at the thoracic outlet that predispose to stent fracture and occlusion. Anticoagulation is continued for 3 to 6 months following rib resection.

### Outcomes

The combination of thrombolysis and first rib resection yields excellent long-term results, with vein patency rates exceeding 90%. Thrombolysis alone without decompression carries a high risk of rethrombosis, reported at 30-40%. In patients presenting late, beyond two weeks with organized thrombus, thrombolysis is less effective; these cases may require mechanical thrombectomy or surgical venolysis with patch angioplasty.

## Arterial Thoracic Outlet Syndrome

### Pathophysiology

Arterial thoracic outlet syndrome results from compression of the subclavian artery within the interscalene triangle. This condition is almost always associated with a bony abnormality such as a cervical rib, an anomalous first rib, or an exostosis. Chronic arterial compression leads to the formation of a post-stenotic aneurysm, which can serve as a source of distal embolization causing digital ischemia.

### Clinical Presentation

Patients often present with symptoms of digital ischemia, including Raynaud phenomenon, blue discoloration of the fingers, cold sensitivity, digital ulceration, or gangrene. A pulsatile supraclavicular mass may be palpable, representing the subclavian artery aneurysm. Arm claudication with overhead activity is less common. On physical examination, the radial pulse may be absent or diminished when the arm is placed in provocative positions such as those used in the Adson, Wright, or Roos tests. Acute presentations may include upper extremity thromboembolism.

### Diagnosis

Chest X-ray may reveal a cervical rib or an elongated transverse process of C7. Duplex ultrasound can detect subclavian artery stenosis or aneurysm. CT angiography is the gold standard, providing detailed visualization of bony anatomy, arterial compression, aneurysm formation, and distal emboli. Arteriography with provocative positioning further demonstrates dynamic arterial compression.

### Treatment

Treatment involves first rib resection and removal of any cervical rib to decompress the artery. Surgical reconstruction of the subclavian artery includes resection of the aneurysm with interposition grafting using PTFE or saphenous vein. If distal embolization has occurred, thrombolysis or thromboembolectomy of the affected upper extremity arteries may be necessary. The preferred surgical approach is supraclavicular, which provides excellent exposure for arterial TOS, though infraclavicular or combined approaches may also be used.

<image>CT angiography showing a cervical rib causing compression of the subclavian artery with post-stenotic aneurysm formation and distal digital artery emboli resulting in fingertip ischemia</image>

## Neurogenic Thoracic Outlet Syndrome

### True Neurogenic TOS

True neurogenic TOS is rare, accounting for less than 1% of cases, and is characterized by objective neurological deficits. It involves compression of the lower trunk of the brachial plexus (C8-T1), leading to wasting of the intrinsic hand muscles such as the thenar, hypothenar, and interossei muscles. Sensory loss occurs in the medial forearm and hand, corresponding to the ulnar nerve distribution. Electromyography and nerve conduction studies confirm lower trunk brachial plexopathy. This form is almost always associated with a rudimentary cervical rib or fibrous band. Treatment consists of first rib resection combined with excision of the cervical rib or fibrous band. While symptoms often improve, motor deficits may not fully recover.

### Disputed (Non-specific) Neurogenic TOS

Disputed neurogenic TOS is the most common form, representing over 95% of cases, and is a diagnosis of exclusion. Patients experience neck, shoulder, arm, and hand pain with paresthesias, often positional in nature. There are no objective neurological findings on examination or electromyography. Provocative tests such as the Adson, Wright hyperabduction, and Roos/EAST tests are frequently positive but lack specificity. The diagnosis is controversial due to significant overlap with other conditions like cervical radiculopathy, rotator cuff disease, carpal tunnel syndrome, and ulnar neuropathy. First-line treatment is physical therapy focusing on scalene muscle stretching, postural correction, and strengthening, which is effective in over 60% of patients. Scalene muscle block with local anesthetic serves both diagnostic and therapeutic purposes. Surgical intervention with first rib resection is reserved for patients who fail 3-6 months of conservative therapy and have consistent symptoms.

### Provocative Tests

Several provocative maneuvers assist in the evaluation of TOS. The Adson test involves turning the head toward the affected side, extending the neck, and taking a deep breath; a loss of the radial pulse suggests compression but has low specificity. The Wright (hyperabduction) test requires arm abduction and external rotation, which may reproduce symptoms and cause pulse loss. The Roos or Elevated Arm Stress Test (EAST) involves abducting the arms to 90 degrees with elbows flexed and repeatedly opening and closing the hands for three minutes, provoking symptoms and arm fatigue. The costoclavicular maneuver entails drawing the shoulders back and downward, which may diminish the pulse.

| TOS Type | Frequency | Structure Compressed | Typical Patient | Key Diagnostic Finding | Treatment |
|----------|-----------|---------------------|-----------------|----------------------|-----------|
| Venous (Paget-Schroetter) | 3–5% | Subclavian vein | Young athlete; overhead activity | Venogram: subclavian thrombosis | Thrombolysis + first rib resection |
| Arterial | 1–2% | Subclavian artery | Cervical rib present | CTA: post-stenotic aneurysm ± emboli | First rib/cervical rib resection + arterial repair |
| True neurogenic | <1% | Lower trunk brachial plexus (C8-T1) | Cervical rib/fibrous band | EMG: lower trunk plexopathy; thenar wasting | First rib resection + band excision |
| Disputed neurogenic | >95% | Brachial plexus (debated) | Variable; repetitive motion | Diagnosis of exclusion; positive scalene block | PT first; surgery if fails 3–6 months |

## Surgical Approaches for First Rib Resection

### Transaxillary Approach

The transaxillary approach is performed with the arm abducted and an incision made below the axillary hairline. This provides exposure of the first rib from the costochondral junction to its posterior scalene attachment. The advantages include a cosmetically favorable incision and good access to the first rib. However, this approach offers limited visualization of the subclavian artery, making it less suitable for arterial TOS. There is also a risk of brachial plexus injury due to limited exposure.

### Supraclavicular Approach

The supraclavicular approach involves an incision above the clavicle along the posterior border of the sternocleidomastoid muscle. This approach allows for anterior and middle scalenectomy and first rib resection. It provides excellent exposure of the subclavian artery, brachial plexus, and cervical rib, making it the preferred method for arterial TOS and recurrent cases. It can be combined with an infraclavicular approach for venous reconstruction.

### Infraclavicular Approach

The infraclavicular approach is performed below the clavicle along the deltopectoral groove. It grants access to the subclavian-axillary vein for venolysis and patch angioplasty. This approach is often used in conjunction with the supraclavicular or transaxillary approaches for venous TOS.

### Paraclavicular Approach

The paraclavicular approach combines supra- and infraclavicular exposures, providing versatile access to all neurovascular structures. It is typically reserved for complex or recurrent thoracic outlet syndrome cases.

## Complications of First Rib Resection

Complications following first rib resection include pneumothorax, occurring in 5-10% of cases, most of which resolve with observation or chest tube placement. Brachial plexus injury occurs in 1-3% of patients, usually as traction neuropraxia that recovers over time. Injury to the subclavian artery or vein, phrenic nerve damage (rare), long thoracic nerve injury resulting in winged scapula (rare), and thoracic duct injury during left-sided approaches are also possible. Recurrent TOS may develop in 5-10% of patients due to incomplete rib resection or scar formation.

<image>Surgical photograph showing the transaxillary approach for first rib resection with identification of the subclavian artery, brachial plexus, and the first rib being excised with rib cutters</image>

## Secondary Upper Extremity DVT

### Catheter-Related

Catheter-related thrombosis is the most common cause of UEDVT, accounting for over 60% of cases. Central venous catheters, peripherally inserted central catheters (PICC lines), port-a-caths, and pacemaker or defibrillator leads are frequent culprits. Treatment primarily involves anticoagulation, with catheter removal recommended if the device is no longer needed and removal is feasible. Thrombolysis is not routinely indicated unless there are severe symptoms or limb-threatening ischemia.

### Cancer-Associated

Cancer-associated UEDVT often occurs in the context of central venous catheters combined with a hypercoagulable state. Anticoagulation with low molecular weight heparin or direct oral anticoagulants, following cancer-associated venous thromboembolism guidelines, is the mainstay of treatment. The catheter may be preserved if it remains functional and necessary.

### Other Causes

Other causes of UEDVT include inherited or acquired hypercoagulable states, ovarian hyperstimulation syndrome, and idiopathic cases. In idiopathic presentations, evaluation for occult malignancy or thrombophilia is warranted.

## Clinical Pearls

Paget-Schroetter syndrome should be considered the venous equivalent of a sports injury; it is important to suspect thoracic outlet syndrome in any young athlete presenting with sudden arm swelling. The urgency for thrombolysis diminishes after two weeks because organized thrombus becomes resistant to lytic agents, making early referral critical. Subclavian vein stenting in venous TOS is generally avoided due to the high compressive forces at the thoracic outlet that predispose stents to fracture and occlusion; first rib resection remains the definitive treatment. Arterial TOS almost invariably involves a bony abnormality such as a cervical or abnormal first rib; absence of such findings should prompt reconsideration of the diagnosis. Disputed neurogenic TOS is a diagnosis of exclusion, requiring careful evaluation to rule out cervical spine disease, rotator cuff pathology, carpal tunnel syndrome, and ulnar neuropathy before attributing symptoms to TOS. A positive scalene muscle block, achieved by injecting local anesthetic into the anterior scalene muscle and observing temporary symptom relief, supports the diagnosis of neurogenic TOS and predicts surgical benefit. Finally, bilateral disease should always be assessed, as cervical ribs and thoracic outlet anatomy are often bilateral even when symptoms are unilateral.

## References
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- Molina JE, et al. Combined surgical treatment for Paget-Schroetter syndrome. *Ann Vasc Surg*. 2019;56:267-274.
- Likes K, et al. Vascular thoracic outlet syndrome: protocol for diagnosis and treatment. *Vasc Endovascular Surg*. 2020;54(2):108-114.
- Thompson RW. Comprehensive management of subclavian vein effort thrombosis. *Surg Clin North Am*. 2014;94(4):833-856.
- Orlando MS, et al. Reoperation for neurogenic thoracic outlet syndrome. *J Vasc Surg*. 2019;70(5):1551-1562.