Most people's hands briefly "fall asleep" every now and then. They then feel numb or tingly. Although this is a little unpleasant, it's usually over very quickly. Carpal tunnel syndrome has similar symptoms – but they keep coming back again and are often painful.
The carpal tunnel is a passageway inside of the wrist that is surrounded by bones and connective tissue. It runs along the inner side of the wrist to the base of the hand and is covered by a strong, fibrous band made up of connective tissue, called the flexor retinaculum. The carpal tunnel contains tendons and the median nerve. This nerve is responsible for sensation and movement in the ball of the thumb and some parts of the hand. If the tissue inside the carpal tunnel swells up, it can put pressure on the median nerve, which is what causes carpal tunnel syndrome. The symptoms often go away on their own, but they can sometimes last for quite a long time. There are a number of different treatments that can provide relief.
The carpal tunnel and the nerves in the hand
Symptoms occur if the tissue in the carpal tunnel becomes swollen, putting pressure on the median nerve.
Carpal tunnel syndrome is associated with the following symptoms:
- Abnormal sensations: Parts of the hand feel numb or may tingle (also called "pins and needles"). Usually, the thumb and the middle three fingers are affected (these appear red in the illustration). Your hand falling asleep at night could be a typical early sign of carpal tunnel syndrome.
- Pain in your fingers: Sometimes the entire hand might also hurt, or the pain may radiate into your arm.
These symptoms are most common at night and in the morning. They usually affect both hands, but not necessarily at the same time. Shaking your hands often improves the symptoms.
It's often difficult to tell exactly what caused the tissue to swell. Overextending or overusing the joint sometimes plays a role. This may happen if you, for instance, put too much pressure on your wrist, or overstretch or twist it. Repetitive activities like using a jackhammer, which makes the wrist vibrate a lot, can also cause the tissue to swell.
The symptoms of carpal tunnel syndrome often get worse when the wrist is exposed to this kind of physical strain. It's not clear whether they can also cause the condition, though. It's commonly believed that working at the computer can increase your risk of carpal tunnel syndrome, but research so far suggests that the effect is minor.
Some conditions can make you more likely to develop carpal tunnel syndrome. These include rheumatism, diabetes, wrist injuries and repeated synovial inflammation. Pregnant women are at greater risk because more fluid builds up in their body’s tissue.
The symptoms may suddenly become very severe, but this only rarely happens. Known as “acute carpal tunnel syndrome,” it is usually caused by an inflammation, injury or bleeding in the wrist.
Carpal tunnel syndrome is most common between the ages of 40 and 70, and very rare in children. Women are more likely to be affected. People who do lots of physical labor are also more likely to have it. It's estimated that about 3 out of 1,000 people develop carpal tunnel syndrome each year.
Some people may have only mild symptoms which come and go over many years. It's estimated that in about 1 out of 3 people the symptoms go away without treatment within six months. In others, the symptoms don't go away. If the condition worsens, the hand may feel numb all the time. In later stages, carpal tunnel syndrome can cause the muscles on the ball of the thumb to waste away (atrophy). If your hand becomes weaker and you can't feel it properly, it can be difficult to do everyday things like hold a teacup.
Your doctor will first ask you about your symptoms and then examine your hand and wrist. There are specific tests to see how well the hand and fingers can move and feel things.
Electrophysiological tests like electroneurography (ENG) may also be needed to find out whether carpal tunnel syndrome is in fact causing the symptoms. This test can measure how effectively the electrical signals are being carried by the nerves, and how well the nerves are working. The results are considered together with the described symptoms, the physical exam, other life circumstances and your medical history.
Ruling out other possible medical causes is also important. For example, changes in the cervical spine (the bones in your neck) may irritate the nerve roots, causing similar symptoms. Other nervous system diseases such as polyneuropathy can also have this effect.
Mild to moderate carpal tunnel syndrome can usually be treated with a splint at first. The splint is worn at night to prevent the wrist from bending too far. Doctors may also advise you to avoid activities thought to be related to this condition.
Injecting corticosteroids into the carpal tunnel can provide temporary relief, but corticosteroid injections aren't an effective long-term solution.
Surgery may also be considered as a treatment. During the operation, the flexor retinaculum that arches across the base of the hand is cut: to reduce pressure on the median nerve. This procedure can make the symptoms go away for good, but it's not always necessary. Other treatments are usually preferred, especially in early stages of the condition. Immediate surgery is only needed in very rare cases of acute carpal tunnel syndrome.
Other treatments such as acupuncture, ultrasound therapy, laser therapy or magnetic field therapy may also be recommended. But there is no evidence that they are effective in the treatment of carpal tunnel syndrome.
Many people take painkillers to relieve their symptoms – particularly non-steroidal anti-inflammatory drugs (NSAIDs), which are available over-the-counter at pharmacies and drugstores. Taking vitamin B6 products is sometimes also recommended to strengthen the nerves. So far, though, research suggests that neither NSAIDs nor vitamin B6 can provide enough pain relief.
When people are ill or need medical advice, they usually go to their family doctor first. Here you can find out how to choose the right practice and how to prepare for your appointment.
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