Carpal tunnel syndrome is a condition caused by compression of the median nerve at the wrist. Within the wrist is a space called the carpal tunnel. Nine tendons and the median nerve all pass through this tunnel from the forearm into the hand. The median nerve is closest to the inside of the wrist and is directly under a large ligament, the transverse carpal ligament, which holds all ten structures in place. An increase in pressure in this tunnel can compress or pinch the median nerve. When the median nerve is compressed, it will often cause pain, numbness, and weakness affecting the hand to the thumb, index, and middle finger.
Carpal tunnel syndrome is often activity-dependent, meaning that when the hands are used more frequently the symptoms are exacerbated. Common activities that bother this nerve in the wrist include typing, writing, or grasping. Many patients will complain of numbness when they sleep, often is often caused by curling the wrist and hand under a pillow. The nerve can be pinched from inflammation of the tendon covering the nerve, joint dislocations, fractures, and arthritis. Other medical conditions, such as problems with the thyroid, rheumatoid arthritis, and diabetes can be associated with carpal tunnel syndrome.
A detailed history is important, not only to understand where you feel pain or sensation changes, but for your provider to learn how you use your hands on a daily basis and if there were any prior injuries to the wrist. A focused physical exam may reproduce your wrist or hand pain, indicating the problem is indeed within this tunnel. Diagnosis can be complicated if you also have neck pain as nerves can also be pinched in the neck causing hand or wrist pain. An EMG is a nerve conduction study and may confirm the diagnosis of carpal tunnel syndrome and check for other nerve problems.
Symptoms may be relieved without surgery. If an underlying medical condition is causing carpal tunnel syndrome, treating it may help reduce associated pain. Medications that decrease inflammation may be helpful. You may be able to find relief by changing how you use your hands throughout the day and find that a wrist splint relieves your symptoms. When these simple measures are not enough, a steroid injection into the carpal tunnel may help relieve pain by provided targeted anti-inflammatory medication directly around the median nerve.
When symptoms are severe or do not improve, a carpal tunnel release surgery may be needed to make more room for the nerve. A surgeon will cut the transverse carpal ligament that covers the nerve on the palm side of the wrist. The goal of this is to increase the size of the tunnel so the median nerve has less pressure and more room to live. At the Virginia Spine Institute, our skilled surgeon Dr. Brian Subach performs this relatively quick outpatient surgery. Following surgery, your wrist may be sore for several weeks or months as you heal. Physical therapy is used to help decrease scar tissue and inflammation, increase mobility, and improve strength. Depending on the severity of symptoms and nerve irritation present prior to surgery, numbness, tingling and strength will generally improve with time after the release surgery.
Double crush is a phenomenon that refers to the presence of nerve irritation at two locations along the path of the nerve. Nerves in our body leave our spine and travel through the body to their final destinations. Thus, nerves leaving the neck, or cervical spine, become nerves that innervate the wrist. Double crush means that irritation at one site, such as the neck, causes enough damage to make the same nerve more susceptible to damage elsewhere, such as the wrist. For carpal tunnel syndrome, a pinched nerve leaving the neck, as seen in cervical radiculopathy, may require less pinching of the median nerve in the wrist to produce painful symptoms than would otherwise be expected if the nerve was only pinched at one location.
Is my hand pain from my neck or from my wrist?
The difference between cervical radiculopathy and carpal tunnel syndrome is often made clinically by using a careful neurologic examination with provocative tests. Provocative tests can show irritation by reproducing hand symptoms caused by either a cervical nerve root in the neck or by the carpal tunnel itself. If a careful physical examination cannot determine the cause of the symptoms, an EMG test may be used. The EMG tests the electrical conduction of nerves and can show which nerves are involved as the nerve endings may be compressed in the neck or as they cross either the elbow or the wrist. When this happens in the elbow it is called cubital tunnel syndrome and affects the ulnar nerve.
The differential diagnosis of cervical radiculopathy versus carpal tunnel syndrome can be difficult for both the provider and the patient. Usually a combination of clinical expertise, a quality physical exam, EMG testing, and physical therapy are helpful in defining the problem.
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