The carpal tunnel receives its name from the 8 bones in the wrist, called carpals, that form a tunnellike structure. The tunnel is filled with flexor tendons which control finger movement. It also provides a pathway for the median nerve to reach sensory cells in the hand. Repetitive flexing and extension of the wrist may cause a thickening of the protective sheaths which surround each of the tendons. The swollen tendon sheaths, or tenosynovitis, apply increased pressure on the median nerve and produce Carpal Tunnel Syndrome (CTS).

The Carpal Tunnel is normally quite snug and there is just barely enough room in it for the tendons and nerves that have to pass through it. If anything takes up extra room in the canal, things become too tight and the nerve in the canal becomes constricted or “pinched”. This pinching of the nerve causes numbness and tingling in the area of the hand that the nerve travels to. The condition that results when the Median Nerve is being pinched in The Carpal Tunnel is commonly referred to as Carpal Tunnel Syndrome or “CTS”.

What Can Cause Carpal Tunnel Syndrome?
The most common cause of Carpal Tunnel Syndrome is inflammation of the tendons in the tunnel which can normally be attributed to repetitive use of the hand and/or wrist.

Repetitive Strain Injuries (RSIs) can happen to anyone whose work calls for long periods of steady hand movement, from musicians & dental hygienists to meat cutters & cashiers. RSIs tend to come with work that demands repeated grasping, turning and twisting; they are especially likely if the work requires repeated twisting or involves repetitive vibration, as in hammering nails or operating a power tool. Stressful hand, arm and neck positions — whether from working at a desk, long-distance driving or waiting on tables — only aggravate the potential for damage.

A number of sports can bring on repetitive stress injuries: Rowing, golf, tennis, downhill skiing, archery, competitive shooting and rock climbing are just a sampling of activities that stress the hand and wrist joints. Injuries and ailments that cause swelling or compression of soft tissue on nerves, such as sprains, leukemia, and rheumatoid arthritis, can lead to stress injuries.

Diabetes, thyroid problems, and other systemic disorders are also associated with discomfort from stressed nerves, as is the fluid accumulation that sometimes accompanies pregnancy. Some authorities believe that a pyridoxine (vitamin B6) deficiency can also induce the symptoms.

Fluid retention, a major contributor to CTS & RSI symptoms naturally occur with the usage of contraceptive pills. Post Menstrual Syndrome (PMS) also causes fluid retention as do many other medical conditions, all of which can result in Carpal Tunnel Syndrome symptoms.

Swelling of the tendons that line the carpal tunnel causes CTS. Although there are many reasons for developing this swelling of the tendon, it can result from repetitive and forceful movements of the wrist during work and leisure activities. Research conducted by the National Institute for Occupational Safety and Health (NIOSH) indicates that job tasks  involving highly repetitive manual acts, or necessitating wrist bending or other stressful wrist postures, are connected with incidents of CTS or related problems. The use of vibrating tools also may contribute to CTS. Moreover, it is apparent that this hazard is not confined to a single industry or job but occurs in many occupations especially those in the manufacturing sector. Indeed, jobs involving cutting, small parts assembly, finishing, sewing, and cleaning seem predominantly associated with the syndrome. The factor common in these jobs is the repetitive use of small hand tools.

Carpal Tunnel Syndrome Symptoms

• A tingling or numb feeling in the hand and/or fingers;

• Shooting pains in the wrist or forearm, and sometimes extending to the shoulder, neck and chest, or foot;

• Difficulty clenching the fist or grasping small objects;

For many unfortunate sufferers, CTS has a pattern of flaring up through the night thereby making sleep difficult. CTS symptoms can also be expected to arise frequently while performing the activity that is the cause of the condition in the first place. 

The symptoms of CTS often first appear as painful tingling in one or both hands during the night, frequently painful enough to disturb sleep. Accompanying this is a feeling of uselessness in the fingers, which are sometimes described as feeling swollen, even though little or no swelling is apparent. As symptoms increase, tingling may develop during the day, commonly in the thumb, index, and ring fingers. A decreased ability and power to squeeze things may follow. In advanced cases, the thenar muscle at the base of the thumb atrophies, and strength is lost. 

Many patients with CTS are unable to differentiate hot from cold by touch, and experience an apparent loss of strength in their fingers. They appear clumsy in that they have trouble performing simple tasks such as tying their shoes or picking up small objects.

How does a patient with carpal tunnel syndrome feel?

Patients with carpal tunnel syndrome initially feel numbness and tingling of the hand in the distribution of the median nerve (the thumb, index, middle, and part of the fourth fingers). These sensations are often more pronounced at night and can awaken patients from sleep. The reason symptoms are worse at night may be related to the flexed-wrist sleeping position and/or fluid accumulating around the wrist and hand while lying flat. Carpal tunnel syndrome may be a temporary condition that completely resolves or it can persist and progress.

Is there any treatment?

Treatment for CTS depends upon the stage of the disease. In the early stage, the syndrome can be reversible and is most often treated with appropriate modification in activities, a removable wrist brace, and anti-inflammatory medicines. In moderate stages of the disorder, especially if the numbness and pain continues in the wrist and hand, a cortisone injection into the carpal tunnel can be extremely beneficial. Surgical intervention in CTS is only indicated in those patients in whom non-operative treatment has failed to eliminate their symptoms. In patients with advanced disease, and especially in those who have profound weakness or muscle atrophy, surgical intervention should be done early. CTS should not be left untreated because it can eventually cause permanent nerve damage.

Initial treatment generally involves resting the affected hand and wrist for at least 2 weeks, avoiding activities that may worsen symptoms, and immobilizing the wrist in a splint to avoid further damage from twisting or bending.    Nonsteroidal anti-inflammatory drugs, such as aspirin, ibuprofen, and other nonprescription pain relievers, may ease pain.   Cool (ice) packs and prednisone (taken by mouth) or lidocaine (injected directly into the wrist) can relieve swelling and pressure on the median nerve and provide immediate, temporary relief.   Stretching and strengthening exercises can be helpful in people whose symptoms have abated.  If symptoms last for 6 months or more, doctors may recommend surgery to sever the band of tissue around the wrist and reduce pressure on the median nerve.