CTS is a collection of symptoms caused when the median nerve at the wrist becomes compressed. One of three major nerves to the hand, the median nerve supplies sensation to the palm side of the thumb, to the index and middle fingers, and to half of the ring finger. It also powers the muscles needed for gripping (see figure 1).
This nerve, along with nine tendons that go to the fingers, passes through a narrow canal (tunnel). Small bones, called carpal bones, border this tunnel on three sides. A thick fibrous band called the flexor retinaculum forms the border on the palm side (see figures 2 and 3).
Often the symptoms of CTS begin at night. A person may wake with numbness, tingling and pain in the hands and forearm. This may often be relieved by shaking the hand. At first these symptoms come and go, but become more constant as the condition worsens.
Next numbness usually appears during the day, especially when grasping objects forcefully or doing repetitive actions with the wrist. As the condition progresses, the hand and wrist become weak, causing clumsiness. There is a tendency to drop objects. In time, fine motor activities, such as grasping zippers and picking up coins, become impossible.
These activities have been associated with CTS:
It is hard to say exactly what causes CTS. Any condition that increases pressure within the carpal canal can compress and interfere with the blood supply to the median nerve, causing symptoms. Pregnancy, low thyroid levels, diabetes, swelling of the tendons, fractures to the wrist, cysts, and arthritis can all have this effect. CTS is more frequent in women, especially those who are obese or over 45.
In the workplace CTS is thought to be related to prolonged forceful grasping, awkward wrist posture, or the use of heavy, vibrating tools. This is believed to cause tendon swelling and fluid build up in the canal. Recent studies, however, have failed to relate repetition alone with carpal tunnel syndrome. In fact, the repetitive nature of keyboarding has been found to actually protect against this condition.
Your doctor may request some tests to rule out the conditions listed above. These might include tests on blood glucose and thyroid function, or to check for arthritis or lack of vitamin B12. An x-ray can rule out an abnormal bone or joint.
If symptoms persist and the other tests are normal, your doctor may refer you to a specialist for a nerve conduction study. This test is considered to be the ‘gold standard’ for confirming a CTS diagnosis.
The test involves placing fine pads, called electrodes, at various points along the wrist and hand. They record the speed and strength of an electrical impulse as it travels along the median nerve through the carpal tunnel.
If this nerve conduction is slowed across the wrist or carpal tunnel, then carpal tunnel syndrome is confirmed.
The conservative treatment of carpal tunnel syndrome will improve 50 to 75 per cent of all cases, especially if diagnosed early. This is especially true in most work-related cases. If you suffer from CTS, especially if it is work-related, the most important first step is to avoid activities that may aggravate the condition. You should avoid prolonged forceful grasping of tools and other objects, awkward wrist positions, and pressure against the palm.
You may be referred to an occupational therapist to have night splints custom fitted. Night splints maintain the hand in an extended (fingers open) position. The night splint is thought to reduce swelling and thus improve the symptoms that occur at night. We normally sleep with our hands closed and flexed. This increases pressure within the wrist.
There is little evidence that use of these splints during the day is helpful. Your doctor may recommend treatments including physiotherapy and medication for arthritis. Occasionally steroids are injected into the wrist.
If symptoms persist after conservative treatment, and the nerve conduction study shows nerve damage, your doctor may refer you to a surgeon. The treatment is a surgical release of the fibrous flexor retinaculum at the wrist. Cutting this fibrous band allows more space for the median nerve as it passes though the carpal canal. The surgery usually improves the condition immediately. The incision
extends from the wrist crease down towards the palm and is usually only two to three centimetres long.
You may need to wear a splint to protect your wrist for seven to ten days after surgery, at which time the stitches are usually removed. Although symptoms may improve soon after surgery, muscle strength may not return for several weeks. Over 90 per cent of cases improve with surgery.
Although no association has yet been proven, a link may exist between lack of vitamin B6 (pyridoxine) and the onset of CTS. In doses of 100 to 200 milligrams per day for 12 weeks, vitamin B6 has relieved pain and numbness for some people.
Vitamin C has not been shown effective for this purpose. In fact, supplementing with vitamin C when a vitamin B6 deficiency exists may injure the nerve. Taking high doses of Vitamin B6, greater than 500 milligrams per day, may also injure the nerve.
Conservative Treatment – 50 to 75 per cent of cases improve
Surgical Treatment – 90 to 95 per cent of cases improve
Carpal tunnel syndrome is not just painful. It also has the potential to disable your hand. See your family doctor at the first sign of symptoms. Care at an early stage is vital to successful treatment and a rapid return to pain-free activity.