Thoracic Outlet Syndrome
Neurogenic Thoracic Outlet Syndrome
What is Neurogenic thoracic outlet syndrome?
The thoracic outlet is a small space just behind and below your collarbone. The blood vessels and nerves that serve your arm and shoulder are located in this space. Thoracic outlet syndrome (TOS) is the presence of a mixture of hand, arm, shoulder, and neck symptoms. All of these symptoms are due to pressure (or compression) against the nerves (called the brachial plexus) or blood vessels within the scalene triangle at the thoracic outlet.
Ninety-five percent (95%) of all cases of TOS are Neurogenic, which is compression of the nerves to the arm and shoulder. Venous TOS occurs only 3 to 4 percent of the time and is due to obstruction or clotting of the main vein to the arm, the subclavian vein. Arterial TOS, is the rarest type, occurring in only 1 percent of cases, and it is due to disease in the artery leading to the arm, the subclavian artery. Almost all cases of arterial TOS are associated with an extra rib (cervical rib) or an abnormal first rib.
What are the symptoms?
- Neurogenic TOS (nTOS), the symptoms are pain, numbness, tingling, and/or weakness in the arm and hand. Also common is a tired feeling in your arm, which is made worse by working with your arms raised over your head. Neck pain and headaches in the back of your head are also frequent symptoms. Another common occurrence is pain that starts in your shoulder and runs down your arm, as well as pain in your fingertips. One can even experience facial pain, jaw pain, ear pain and pain on the front of your chest. Unfortunately, the symptoms of neurogenic TOS can be vague and non-specific.
- Venous TOS (vTOS) is distinguished by swelling in your entire arm, plus pain and dark discoloration.
- Arterial TOS (aTOS) presents with pain, coldness, and a pale discoloration of the hand. Cramps occur when using the arm for activity.
What causes thoracic outlet syndrome?
Neurogenic TOS is most often the result of neck trauma such as a whiplash injury. Motor vehicle accidents, traction injuries to shoulder, slipping and falling on floors or ice, blunt injury to base of neck or top of shoulder, or repetitive stress from working on assembly lines are the common causes.
The symptoms are due to trauma and scar tissue formation in; neck muscles (called scalene muscles) and the nerves (brachial plexus). Congenital deformities of the first rib or having an anomalous cervical rib or band significantly increases the risk of acquiring this condition. Ultimately, the cause is compression and tethering of the brachial plexusnerves at the thoracic outlet.
How is thoracic outlet diagnosed?
Diagnosing TOS can be complex. It begins by your physician asking you a series of questions to find out your symptoms, the distribution of these symptoms and and how the symptoms began. Depending on your symptoms, the doctor will be able to tell if you might have a nerve, vein, or artery compression. An appropriate physical examination will be beneficial in determining your diagnosis as well. It is not uncommon that patients have seen several physicians and have been evaluated for cervical neck problems and shoulder problems prior to the referral for evaluation of thoracic outlet syndrome.
In arterial TOS, a physical exam often finds the pulse at your wrist is diminished or absent. Your hand may have a pale color compared to your pink, good hand.
Venous and arterial TOS are best diagnosed with the aid of specific tests, venography for venous TOS, and pulse volume or arteriography for arterial TOS.
How is thoracic outlet syndrome treated?
Your particular treatment will depend on the type of TOS you have. Determined by your symptoms, physical examination, and test results.
Surgery for nTOS involves removing certain muscles in your neck and cleaning scar tissue off the nerves of the brachial plexus. The anterior and middle scalene muscles are the muscles making the scalene triangle in the neck at the thoracic outlet. These muscles are a source of the pathology and injury to them will cause compression to the brachial plexus nerves. There are many redundant muscles in the neck, allowing for us to release or resect one or both of these muscles. Additionally, the nerves at this level need to be released from scar tissue or fibrosis that have formed around them. This encasing tissue is much like shrink-wrap and causes both compression and tethering of the nerve. Releasing this tissue relieves compression and re-establishes the much needed gliding surfaces of these nerves.
Surgery for thoracic outlet syndrome, however, is never without risks. There are vital structures in this part of the body that can be injured during TOS decompression surgery. Rates of complications are very low but they are not zero. These rare problems include; persistence of pain, hematoma, phrenic nerve injury, surgical infection, nerve injury resulting hand or arm dysfunction, surgical site infection, arterial injury or pneumothorax
In addition, surgery does not always relieve the symptoms of neurogenic TOS. Our success rate is currently 80 to 90%. Larger studies evaluating outcomes from surgery for neurogenic TOS demonstrate that only up to 70 percent of patients have an improvement in their symptoms, while 30 percent may feel no better or worse. We feel that our success rate is higher based upon rigorous patient selection and because we rarely recommend the first rib resection.