WHAT IS THORACIC OUTLET SYNDROME?
The thoracic outlet is the space containing a neurovascular bundle (brachial plexus, subclavian vein, and subclavian artery) located between the collar bone and first rib. Thoracic outlet syndrome (TOS) is a constellation of signs and symptoms that arise from compression or irritation of the neurovascular bundle. TOS is primarily a unilateral condition.
There are three general types of thoracic outlet syndrome:
- Neurogenic: involving the brachial plexus
- Venous: involving the subclavian vein
- Arterial: involving the subclavian artery
Neurogenic thoracic outlet syndrome is the most common, accounting for greater than 95% of cases, whereas venous thoracic outlet syndrome accounts for 3% and arterial thoracic outlet syndrome accounts for 1%. The incidence of neurogenic TOS is approximately 3 out of 100,000 per year and venous TOS is 1 out of 100,000 per year. Thoracic outlet syndrome may occur at any age, but is most commonly found in women between the ages of 20 to 50.
WHAT CAUSES THORACIC OUTLET SYNDROME?
- Developmental abnormalities: cervical rib (additional rib that forms above the collarbone) or variations in muscle anatomy
- Injuries: involving neck hyperflexion or hyperextension
- Repetitive motions: chronic inflammation from repetitive physical activity such as lifting overhead, pitching, or swimming
- Poor posture: holding head in the forward position or drooping shoulders
- Carrying heavy bags over the shoulder: increases pressure in the thoracic outlet
- Obesity: increases stress on the joints
- Pregnancy: common for joints to loosen during pregnancy
WHAT ARE THE SYMPTOMS OF THORACIC OUTLET SYNDROME?
- Paresthesia (tingling sensations)
- Weakness especially with raising the affected arm
- Muscle atrophy
- Cyanosis (bluish discoloration)
- Arm fatigue with activity
- Cold, pale arm or fingers
- Decreased blood pressure in the affected arm
- Decreased pulse in the affected arm
HOW IS THORACIC OUTLET SYNDROME DIAGNOSED?
- Review of medical history and physical examination
- Imaging modalities such as x-ray, ultrasound, CT, MRI, or angiography depending on the type of TOS suspected
- Diagnostic injection into the scalene muscles
HOW IS THORACIC OUTLET SYNDROME TREATED?
- Physical therapy
- Medications: anti-inflammatories or muscle relaxants
- Therapeutic injections: steroid injections, botox injections
- Surgery for decompression