Overview
Definition:
Thoracic outlet syndrome (TOS) is a group of disorders caused by compression of blood vessels or nerves in the thoracic outlet, the space between the collarbone (clavicle) and the first rib
First rib resection is a surgical procedure aimed at decompressing the neurovascular structures by removing the first rib, which is often a primary cause of compression in certain types of TOS.
Epidemiology:
TOS affects approximately 3-8% of the general population
Neurogenic TOS is the most common form (90-95%), followed by venous TOS (4-5%) and arterial TOS (1-2%)
The condition is more prevalent in young adults, particularly women, and individuals with certain occupations or repetitive arm movements
First rib abnormalities or an elongated C7 transverse process are implicated in a significant subset of these cases.
Clinical Significance:
Untreated TOS can lead to chronic pain, functional impairment of the upper extremity, and potentially serious vascular complications like deep vein thrombosis (DVT) or arterial aneurysm/thrombosis
Surgical intervention, including first rib resection, is crucial for patients refractory to conservative management, offering significant relief and preventing long-term sequelae, thereby improving quality of life and functional outcomes.
Clinical Presentation
Symptoms:
Neurologic symptoms: Paresthesias (tingling, numbness) in the arm and hand, especially the ulnar distribution
Weakness and fatigue of the arm
Pain in the neck, shoulder, and arm
Vascular symptoms: Arm swelling and cyanosis (venous TOS)
Arm pallor, coldness, and fatigue with exertion (arterial TOS)
Arm pain and claudication
Discoloration
Headache
Positional pain
Symptoms often exacerbated by overhead arm activity or carrying heavy objects.
Signs:
Tenderness over the supraclavicular fossa
Palpable supraclavicular mass or anomalous rib
Diminished radial pulse with provocative maneuvers (Adson's test, Wright's test, Roos test)
Bruit over the supraclavicular fossa
Edema and cyanosis of the arm (venous TOS)
Pallor and coolness of the hand (arterial TOS)
Atrophy of the thenar eminence (rare, severe neurogenic TOS).
Diagnostic Criteria:
No single definitive diagnostic test exists
Diagnosis is typically based on a combination of suggestive history, physical examination findings, and exclusion of other causes
Consensus diagnostic criteria often include: 1
Symptoms consistent with TOS
2
Provocative maneuvers eliciting symptoms
3
Objective evidence of neurovascular compression (e.g., imaging findings, electrophysiologic tests showing abnormalities)
4
Exclusion of other conditions mimicking TOS.
Diagnostic Approach
History Taking:
Detailed history of symptom onset, character, location, and duration
Aggravating and alleviating factors, particularly related to arm position and activity
Occupation and avocations involving repetitive arm movements
Past medical history of trauma, surgery, or vascular disease
Family history of TOS or clotting disorders
Red flags: sudden onset of severe pain, progressive weakness, limb swelling, or systemic symptoms suggesting infection or malignancy.
Physical Examination:
Thorough neurovascular examination of the upper extremities
Palpation of the supraclavicular fossa for tenderness, masses, or cervical rib
Assessment of pulses (radial, ulnar) bilaterally
Provocative maneuvers: Adson's test (head turned to ipsilateral side, inspiratory hold)
Wright's test (arm hyperabducted)
Roos (EAST) test (arms abducted 90 degrees, externally rotated, elbows flexed 90 degrees, rapid hand opening/closing for 3 minutes)
Auscultation for bruits
Assessment of neck range of motion and spinal alignment.
Investigations:
Imaging: Chest X-ray (to identify cervical rib or anomalous first rib)
Ultrasound (duplex scan) of the thoracic outlet to assess venous or arterial flow and compressibility
MRI of the cervical spine and brachial plexus to visualize neural elements and surrounding anatomy
CT scan with dynamic imaging or venography/arteriography may be used to confirm vascular compression
Electrophysiology: Nerve conduction studies (NCS) and electromyography (EMG) can help exclude peripheral nerve entrapments and sometimes demonstrate abnormalities in neurogenic TOS, particularly involving the ulnar nerve distribution.
Differential Diagnosis:
Cervical radiculopathy
Carpal tunnel syndrome
Cubital tunnel syndrome
Thoracic disc herniation
Rotator cuff pathology
Pancoast tumor
Peripheral nerve entrapments
Myofascial pain syndrome
Adson's syndrome
Vascular insufficiency unrelated to TOS
Raynaud's phenomenon
Thoracic outlet venous compression syndrome.
Management
Initial Management:
Conservative management is the first line for most TOS patients
This includes: Activity modification and avoidance of aggravating postures
Physical therapy to improve posture, strengthen scapular stabilizers, and stretch tight muscles
Pain management with NSAIDs or other analgesics
Postural education.
Medical Management:
Analgesics: Non-steroidal anti-inflammatory drugs (NSAIDs) for mild to moderate pain
Muscle relaxants may be used for associated muscle spasms
Neuropathic pain agents (e.g., gabapentin, pregabalin) for nerve-related symptoms
Anticoagulation or thrombolysis is indicated for acute venous or arterial thrombosis associated with TOS.
Surgical Management:
Surgical first rib resection is indicated for patients with persistent, disabling symptoms unresponsive to conservative treatment, or for those with objective evidence of significant neurovascular compression
Indications include: disabling neurogenic TOS with objective findings, symptomatic venous TOS (e.g., Paget-Schroetter syndrome), and symptomatic arterial TOS
The primary surgical procedure is first rib resection via a supraclavicular or transaxillary approach, often combined with scalenectomy and neurolysis
Vascular decompression may involve venolysis or arterial reconstruction.
Supportive Care:
Postoperative care focuses on pain management, wound care, and early mobilization
Physical therapy is crucial to regain strength and function
Long-term monitoring for recurrence of symptoms or complications
Patients with vascular TOS may require long-term anticoagulation.
Complications
Early Complications:
Bleeding
Infection
Pneumothorax
Horner's syndrome (oculomotor nerve injury)
Phrenic nerve injury
Wound seroma or hematoma
Brachial plexus injury (neuropraxia or axonotmesis)
Recurrent laryngeal nerve injury
Vascular injury (e.g., subclavian artery or vein damage).
Late Complications:
Recurrence of TOS symptoms
Chronic pain syndrome
Persistent neurovascular deficits
Scarring and adhesions
Pseudoaneurysm or fistula formation
Thrombosis of remaining subclavian vein or artery
Winging of the scapula
Fibrosis of the scalene muscles.
Prevention Strategies:
Meticulous surgical technique with careful identification and protection of vital structures
Intraoperative neuromonitoring
Use of appropriate surgical approach
Careful preoperative patient selection
Aggressive postoperative rehabilitation
Patient education regarding activity restrictions and warning signs.
Prognosis
Factors Affecting Prognosis:
Type of TOS (neurogenic vs
vascular)
Severity of compression
Duration of symptoms prior to surgery
Presence of objective neurovascular abnormalities
Patient's compliance with postoperative rehabilitation
Surgeon's experience
Presence of comorbidities.
Outcomes:
Surgical outcomes vary but can be excellent for properly selected patients
Success rates for first rib resection range from 60-90%
Significant improvement in pain and function is expected
Vascular TOS often has excellent outcomes with decompression and anticoagulation
Neurogenic TOS outcomes can be more variable, with complete resolution not always achievable, especially if nerve damage is long-standing.
Follow Up:
Regular follow-up appointments are essential, particularly in the first 6-12 months post-surgery
This includes clinical assessment for symptom recurrence, functional evaluation, and sometimes repeat imaging or electrophysiological testing if indicated
Long-term monitoring for vascular TOS patients is crucial to detect potential late thrombotic events.
Key Points
Exam Focus:
Differentiate between neurogenic, venous, and arterial TOS
Understand the anatomical structures at risk in the thoracic outlet
Recognize provocative maneuvers and their significance
Know the indications for surgical intervention, especially first rib resection
Be aware of potential intraoperative and postoperative complications
Understand the role of imaging and electrophysiology in diagnosis.
Clinical Pearls:
A thorough history and physical exam are paramount for diagnosing TOS
Always consider TOS in patients with non-specific arm pain and paresthesias, especially those with repetitive arm use
Provocative tests are helpful but not always diagnostic
Early diagnosis and management can prevent long-term disability
Surgical first rib resection is effective for carefully selected patients with disabling TOS.
Common Mistakes:
Over-reliance on provocative tests without correlating with history and other findings
Failure to rule out other causes of arm pain (e.g., cervical radiculopathy, peripheral nerve entrapments)
Delaying surgical referral in patients with severe or progressive neurovascular compromise
Inadequate preoperative assessment and patient selection
Insufficient postoperative rehabilitation.