Thoracic outlet syndrome (TOS) is a cluster of symptoms that may result in severe pain and dysfunction in the affected shoulder and arm. Your thoracic outlet is the space between your collarbone or clavicle and your first rib. There are a lot of blood vessels and nerves running through that area, and if there is chronic pressure on those vessels or nerves, it causes the symptoms known as TOS.
The compression that causes TOS can be caused by injury, disease, or a congenital deformity. Some people are born with an extra rib or with a tight abnormal fibrous band of tissue connecting a vertebra to the rib. The syndrome can also be related to an abnormality of the vertebral body itself. If you have a long neck with droopy shoulders, that can put more pressure on this area as well.
Some sources have a more specific definition of TOS than others. Neurologically speaking, this is a rare syndrome that causes muscle wasting and weakness of the hand, most often related to an abnormal seventh cervical (neck) vertebrae. This stretches the nerves in the area, causing parasthesias such as numbness and tingling along with weakness in the last two fingers. However, for general purposes, symptoms caused by pressure on the blood vessels in the same area are also referred to as TOS.
The most common symptoms of TOS may include:
• Pain, numbness, and tingling in the last three fingers and inner forearm
• Pain and tingling in the neck and shoulders (carrying something heavy may make the pain worse)
• Signs of poor circulation in the hand or forearm
• Weakness of the muscles in the hand
• Clumsy hand movements
• Cold weather sometimes worsens symptoms
Testing usually involves X-ray and MRI, electromyography and nerve conduction velocity studies. These tests help locate structures that may be causing pressure, measure nerve function, and rule out other conditions such as carpal tunnel or cubital tunnel syndrome.
Treatment starts with physical therapy. This is often enough, especially if nerve damage is not too severe. The focus will be on strengthening the shoulders, improving range of motion, and working on posture.