Risk factors of Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is a condition which occurs when the median nerve which runs from the forearm into the palm of the hand, becomes pressed or squeezed at the wrist. The syndrome typically affects the thumb, index, and middle fingers and is often particularly troublesome at night. The median nerve travels down the forearm and enters the hand after passing through the wrist tunnel (carpal tunnel) that is located in the central part of the wrist. It appears to be caused by a combination of genetic and environmental factors. Some of the predisposing factors include: diabetes, obesity, pregnancy, hypothyroidism, and heavy manual work or work with vibrating tools. There is, however, little clinical data to prove that lighter, repetitive tasks can cause carpal tunnel syndrome. Other disorders such as bursitis and tendinitis have been associated with repeated motions performed in the course of normal work or other activities.

CTS is more common in women than men. In the UK, about three in 100 men and five in 100 women experience CTS is their lifetime.

Although CTS becomes more common with age, it can affect people of all ages. 

Causes

Carpal tunnel syndrome is caused by compression of one of the nerves that controls sensation and movement in the hands (median nerve).

The carpal tunnel is a narrow passage in your wrist made up of small bones and a tough band of tissue that acts as a pulley for the tendons that bend the fingers.

It isn't known why the median nerve becomes compressed in most cases, although certain things are thought to increase the risk of CTS developing, such as:

• a family history of CTS
• pregnancy – up to about 50% of pregnant women develop CTS
• injuries to the wrist
• other health conditions, such as diabetes and rheumatoid arthritis
• strenuous, repetitive work with the hand

Symptoms

Symptoms usually start gradually, with frequent burning, tingling, or itching numbness in the palm of the hand and the fingers, especially the thumb and the index and middle fingers. Some carpal tunnel sufferers say their fingers feel useless and swollen, even though little or no swelling is apparent. The symptoms often first appear in one or both hands during the night, since many people sleep with flexed wrists. A person with carpal tunnel syndrome may wake up feeling the need to "shake out" the hand or wrist. As symptoms worsen, people might feel tingling during the day. Decreased grip strength may make it difficult to form a fist, grasp small objects, or perform other manual tasks. In chronic and/or untreated cases, the muscles at the base of the thumb may waste away. Some people are unable to tell between hot and cold by touch.

Risk Factors

A number of factors have been associated with carpal tunnel syndrome. Although by themselves they don't cause carpal tunnel syndrome, they may increase your chances of developing or aggravating median nerve damage. These include:

• Anatomic factors. A wrist fracture or dislocation that alters the space within the carpal tunnel can create extraneous pressure on the median nerve.

People with smaller carpal tunnels may be more likely to have carpal tunnel syndrome.

• Sex. Carpal tunnel syndrome is generally more common in women. This may be because the carpal tunnel area is relatively smaller than in men, and there may be less room for error.

Women who have carpal tunnel syndrome may also have smaller carpal tunnels than women who don't have the condition.

• Nerve-damaging conditions. Some chronic illnesses, such as diabetes, increase your risk of nerve damage, including damage to your median nerve.
• Inflammatory conditions. Illnesses that are characterized by inflammation, such as rheumatoid arthritis, can affect the tendons in your wrist, exerting pressure on your median nerve.
• Alterations in the balance of body fluids. Fluid retention, common during pregnancy or menopause, may increase the pressure within your carpal tunnel, irritating the median nerve. Carpal tunnel syndrome associated with pregnancy generally resolves on its own after pregnancy.
• Other medical conditions. Certain conditions, such as menopause, obesity, thyroid disorders and kidney failure, may increase your chances of carpal tunnel syndrome.
• Workplace factors. It's possible that working with vibrating tools or on an assembly line that requires prolonged or repetitive flexing of the wrist may create harmful pressure on the median nerve or worsen existing nerve damage.

However, the scientific evidence is conflicting and these factors haven't been established as direct causes of carpal tunnel syndrome.

Several studies have evaluated whether there is an association between computer use and carpal tunnel syndrome. However, there has not been enough quality and consistent evidence to support extensive computer use as a risk factor for carpal tunnel syndrome, although it may cause a different form of hand pain.

Diagnosis

Your doctor may conduct one or more of the following tests to determine whether you have carpal tunnel syndrome:

• History of symptoms. Your doctor will review your symptoms. The pattern of your signs and symptoms may offer clues to their cause. For example, because the median nerve doesn't provide sensation to your little finger, symptoms in that finger may indicate a problem other than carpal tunnel syndrome.

Another clue is the timing of the symptoms. Usual times when you experience symptoms due to carpal tunnel syndrome include while holding a phone or a newspaper, gripping a steering wheel, or waking up during the night.

• Physical examination. Your doctor will conduct a physical examination. He or she will test the feeling in your fingers and the strength of the muscles in your hand.

Pressure on the median nerve at the wrist, produced by bending the wrist, tapping on the nerve or simply pressing on the nerve, can bring on the symptoms in many people.

• X-ray. Some doctors recommend an X-ray of the affected wrist to exclude other causes of wrist pain, such as arthritis or a fracture.
• Electromyogram. Electromyography measures the tiny electrical discharges produced in muscles. During this test, your doctor inserts a thin-needle electrode into specific muscles. The test evaluates the electrical activity of your muscles when they contract and when they're at rest. This test can determine if muscle damage has occurred and also may be used to rule out other conditions.
• Nerve conduction study. In a variation of electromyography, two electrodes are taped to your skin. A small shock is passed through the median nerve to see if electrical impulses are slowed in the carpal tunnel. This test may be used to diagnose your condition and rule out other conditions.

Your doctor may recommend that you see a doctor trained in brain and nervous system conditions (neurologist), brain and nervous system surgery (neurosurgeon), hand surgery, rheumatoid arthritis, or other areas if your signs or symptoms indicate other medical disorders or need additional treatment.

Treatment

A non-surgical option may be advised if your symptoms are mild. For example, if your symptoms come and go and mainly consist of tingling, pins and needles or mild discomfort. A wrist splint (brace) may work but a steroid injection is probably the most effective non-surgical treatment.

Nonsurgical therapy

If the condition is diagnosed early, nonsurgical methods may help improve carpal tunnel syndrome. Methods may include:

• Wrist splinting. A splint that holds your wrist still while you sleep can help relieve nighttime symptoms of tingling and numbness. Nocturnal splinting may be a good option if you're pregnant and have carpal tunnel syndrome.
• Nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs such as ibuprofen (Advil, Motrin IB, others) may help relieve pain from carpal tunnel syndrome in the short term.

There isn't evidence, however, that these drugs improve carpal tunnel syndrome.

• Corticosteroids. Your doctor may inject your carpal tunnel with a corticosteroid such as cortisone to relieve your pain.

Corticosteroids decrease inflammation and swelling, which relieves pressure on the median nerve. Oral corticosteroids aren't considered as effective as corticosteroid injections for treating carpal tunnel syndrome.

If you try a non-surgical treatment and it does not work, do return to your doctor. In particular, if you have constant numbness in any part of your hand, or if you have any weakness of the muscles next to the thumb. These symptoms mean that the nerve is not working well and is at risk of permanent damage.

Surgery gives the best chance of long-term cure. It is quite a common operation. It is done if symptoms continue (persist) despite other treatments, or if symptoms are severe and the nerve is in danger of permanent damage.

Treatment for severe symptoms

If you have severe symptoms, in particular wasting of the muscles at the base of the thumb, then you will probably need surgery. This is to relieve pressure on (decompress) the trapped nerve quickly which aims to prevent any permanent long-term nerve damage.

Carpal tunnel syndrome during pregnancy

Symptoms commonly go after the baby is born. Therefore, a non-surgical treatment, such as a splint, is usually advised at first. Surgery is an option if symptoms persist.

Self-care after surgery for carpal tunnel syndrome

Follow your doctor’s advice, but general suggestions include:

• If you go home within a day or two of surgery, you will probably need some help around the house.
• Continue your medication as ordered by your doctor.
• Cold packs applied at regular intervals can help reduce post-operative swelling.
• Rest the hand as much as you can for at least four weeks following surgery.