Carpal Tunnel Syndrome
Carpal tunnel syndrome causes tingling, numbness, and weakness in the hand. It is caused by compression of the median nerve where it enters the hand. The median nerve supplies feeling to the thumb, the index, the middle, and half of the ring finger. This nerve, like all nerves, starts in the spinal cord (in the neck) and travels the full length of the arm and forearm. It enters the hand on the palm side through the carpal canal. In this canal are nine tendons which go out to the fingers and thumb and are responsible for motion at the individual finger joints.
Increased pressure within this tunnel will cause pressure on the nerve, which causes it to malfunction. Swelling of the tendons within the carpal tunnel increases pressure within the tunnel. Other causes include injury, broken bones, diabetes, hypothyroidism, pregnancy, birth control pills, fluid retention, rheumatoid arthritis, and tumors.
It is more common in women than men. Repeated injury to the hand and vibration producing power tools can contribute. Carpal tunnel syndrome is NOT the only possible cause of numbness or tingling in the hand. Compression and malfunction of the median nerve anywhere may cause very similar symptoms. The problem may originate in the neck, and if so, treatment of the hand alone is bound to fail.
Carpal tunnel syndrome can usually be diagnosed in the office with simple tests. Nerve conduction studies may be ordered by your physician. They are usually performed by neurologists or rehabilitation physicians.
Many patients with carpal tunnel syndrome can be treated with splints and/or injections of medications near the nerve. Patients for whom these treatments are successful generally have mild symptoms. Splints immobilize the wrist and decrease the friction between the nerve and adjacent tendons, bones, and ligaments. The physician may recommend light duty at work for a period of time.
Injection of medication into the carpal tunnel is often effective, and may be helpful in establishing the diagnosis. This medication decreases local swelling and inflammation, decreasing pressure on the median nerve.
In some patients such conservative treatment is not effective and surgery may be recommended. If the initial symptoms are sufficiently severe, your physician may recommend surgery immediately.
If surgery is performed, one or two incisions are made in the palm of the hand. The surgeon will divide the transverse carpal ligament, which forms the roof of the carpal tunnel. By so doing, pressure is relieved on the median nerve and the other structures in the carpal tunnel. Sometimes thickening and scarring of the covering of the median nerve requires further surgery. In patients with fracture or other extrinsic causes of compression, these causes are addressed.
Your surgeon may recommend release of the carpal tunnel with an endoscope. Slightly smaller incisions will be made in the hand. Your physician may feel that you would benefit from this procedure.
The operation is usually performed on an outpatient basis under local or regional anesthesia. You will be able to go home the same day as your surgery.
A dressing will be applied to your hand after surgery. This will be removed, along with sutures, one to two weeks after surgery. It is very important to keep the fingers moving frequently after the operation. Hand therapists may be called upon to instruct you in exercises during the recovery phase.
Patients sometimes experience soreness of their surgical incisions for some weeks after surgery. Heavy hand use should be avoided for up to six weeks after surgery. Some discomfort in the region of the incision may persist for months. Tingling is usually relieved soon after surgery. Loss of feeling or muscle strength may take much longer to recover, and may not recover completely. The extent and speed of this recovery will depend on the length of time symptoms were present before surgery and the extent of the nerve damage present.
Research continues into the causes of, and alternate treatments for carpal tunnel syndrome. Recent developments include a better understanding of which patients may benefit most from conservative (splint and injection) therapy and which will probably need surgery, and development of the endoscopic technique for release of the transverse carpal ligament.