Definition

Carpal tunnel syndrome can be caused by compression of the median nerve at the wrist, which can lead to pain and weakness in the hand. The median nerve supplies sensation to the thumb and first two fingers, and also to some of the muscles of the hand.

Description
The carpal tunnel is composed of two walls - the deep wall is the bones of the wrist and the superficial wall is a thick ligament located just under the skin on the palm side of the wrist.

The tendons which flex the fingers (to form a fist) and the median nerve pass through this tunnel.

Certain conditions like wrist fractures and over-use syndromes can cause swelling in the carpal tunnel. Sometimes there is no identifiable cause. Because the walls of the tunnel are rigid, the swelling increases pressure. Nerves are very sensitive to pressure, and when the median nerve is compressed, the muscles it supplies become weak and the skin over the thumb, index, and middle fingers becomes painful, tingly, or even numb.

Indications
Patients who have symptoms consistent with carpal tunnel syndrome (pain in the first three fingers, shooting pain from the wrist to the fingertips, hand weakness, pain when the palm side of the wrist is tapped) will usually undergo non-surgical treatment first. This includes anti-inflammatory medications, wrist splints, occupational therapy, and workplace modification. If this fails to improve symptoms, an injection of steroids into the carpal tunnel may be helpful.

If all these modalities fail to help, then most surgeons will use a test called an EMG to test the electrical activity of the median nerve. If the results of the test are consistent with carpal tunnel syndrome, carpal tunnel release surgery can be done.

Risks
Risks for any anesthesia are:

 
• allergic reactions to medications  
• problems breathing

Risks for any surgery are:

 
• bleeding  
• infection

Risks specific to carpal tunnel release are:

 
• injury to the median nerve or its branches  
• failure of the surgery to improve symptoms

Expectations after surgery

Carpal tunnel release is successful in improving strength and decreasing pain in about 85% properly selected patients. However, the longer the symptoms have been present, the longer the recovery time and the more variable the extent of recovery.

Convalescence
A splint may be used to reduce wrist motion for the first few days after surgery, but motion should not be delayed for too long because the wrist can become stiff. The surgery is usually done on an outpatient basis. Complete recovery can take anywhere from several weeks to a year, depending on the severity of damage to the nerve. The longer the symptoms lasted before surgery and the more severely damaged the nerve appears at surgery, the longer the recovery time.