Carpal Tunnel Syndrome


What is it?

Carpal Tunnel Syndrome is a term that is often used incorrectly. Many people will call any wrist or hand ailment “Carpal Tunnel Syndrome”. This is wrong. Carpal Tunnel Syndrome is a very specific condition. As Figures 1 and 2 illustrate, the carpal tunnel is a specific physical space at the wrist. It is bordered on three sides by bone and on the palm (or volar) side by a thick ligament . This space is constrained and cannot expand . Within the carpal tunnel run nine tendons (two to each finger and one to the thumb) as well as the median nerve. Carpal Tunnel Syndrome occurs when pressure builds within the carpal tunnel from swelling of the tendons and puts pressure on the nerve . When the pressure becomes great enough, the nerves stop working normally and the individual develops numbness, tingling and pain in the hand and fingers.

Causes

There are many causes of Carpal Tunnel Syndrome. All these causes have in common that they make the flexor tendons swell creating pressure on the nerve . The most common causes of Carpal Tunnel Syndrome are repetitive activity and the normal aging process. Other causes include fractures, arthritis, fluid retention during pregnancy, and metabolic diseases such as thyroid conditions and rheumatoid arthritis. In many cases, Carpal Tunnel Syndrome is caused by a combination of one or more of these factors.

Signs and Symptoms

Symptoms of Carpal Tunnel Syndrome include pain, numbness, and tingling. One hallmark of Carpal Tunnel Syndrome is the development of night pain, which awakes the patient at night. This is usually relieved by shaking the hand.This can often be prevented by use of a wrist splint at night. Numbness is most frequently in the thumb, index, middle and ring fingers and spares the small finger. Numbness is also reproduced by daily activity such as driving or reading a newspaper. As Carpal Tunnel Syndrome becomes more advanced, the numbness may be constant and the patient may also notice a loss of grip strength as well as clumsiness due to loss of sensation. This can lead to a tendency to drop things or difficulty doing fine activities such as buttoning buttons. In severe cases, the sensation may be permanently lost and the muscles at the base of the thumb may atrophy causing difficulty with pinching.

Local Diagnosis

Often, the diagnosis of Carpal Tunnel Syndrome can be made based on history and physical examination. An x-ray may be obtained to evaluate for arthritis or other related conditions. A nerve conduction study will generally be obtained to confirm the diagnosis of Carpal Tunnel Syndrome as well as to check for other possible nerve problems. In some patients with Carpal Tunnel Syndrome, the situation may be complicated by pressure on the nerves at the neck as well as at the wrist. In these cases, it generally makes sense to treat the Carpal Tunnel Syndrome and then assess whether any residual problems relating to the nerve being pinched at the neck will require treatment.

Treatment

In early cases of Carpal Tunnel Syndrome, the symptoms can sometimes be relieved without surgery. This can include the use of a wrist splint at night as well as changes in activity during the day. In patients who have only had symptoms for a short period of time, cortisone injection can sometimes be helpful as well. In more chronic or severe cases of Carpal Tunnel Syndrome, surgery is often the best option. All surgery for Carpal Tunnel Syndrome involves dividing the transverse carpal ligament to make more room and take pressure off the median nerve (See Figure 2).The transverse carpal ligament attaches to an arch of bones.When the ligament is divided, the ends pull apart. Eventually, this area heals with new collagen, but when it does so, the space of the carpal tunnel is increased by approximately twenty five percent.This has been proven by CT scans done before and after carpal tunnel surgery.The surgery is done in a minimally invasive way: either endoscopically, utilizing a camera, or micro surgically utilizing magnification to allow the surgeon to see through a very small incision. After surgery, a splint is applied to the wrist for approximately one week.The patient is encouraged to move the fingers immediately.There is generally tenderness in the palm at the levels where the transverse carpal ligament attaches to the bone, not directly at the site of the incision.This will often last for several weeks or months.While this does not stop the individual from using the hand, it may take several months to regain full grip strength. In many cases, the numbness and tingling will disappear very quickly. Generally, night pain disappears immediately. In some more advanced cases, it may take up to six months for the numbness in the hand to resolve.