Carpal tunnel syndrome
Carpal tunnel syndrome is a hand and arm condition that causes numbness, tingling and other symptoms. Carpal tunnel syndrome is caused by a pinched nerve in your wrist.
A number of factors can contribute to carpal tunnel syndrome, including the anatomy of your wrist, certain underlying health problems and possibly patterns of hand use.
Bound by bones and ligaments, the carpal tunnel is a narrow passageway located on the palm side of your wrist. This tunnel protects a main nerve to your hand and the nine tendons that bend your fingers.
Compression of the nerve produces the numbness, tingling and, eventually, hand weakness that characterize carpal tunnel syndrome.
Fortunately, for most people who develop carpal tunnel syndrome, proper treatment usually can relieve the tingling and numbness and restore wrist and hand function.
Carpal tunnel syndrome usually starts gradually with numbness or tingling in your thumb, index and middle fingers that comes and goes. This may be associated with discomfort in your wrist and hand. Common carpal tunnel syndrome symptoms include:
- Tingling or numbness.You may experience tingling and numbness in your fingers or hand, especially your thumb and index, middle or ring fingers, but not your little finger. This sensation often occurs while holding a steering wheel, phone or newspaper or, commonly, waking you from sleeping. The sensation may extend from your wrist up your arm.
Many people "shake out" their hands to try to relieve their symptoms. As the disorder progresses, the numb feeling may become constant.
- You may experience weakness in your hand and a tendency to drop objects. This may be due to the numbness in your hand or weakness of the thumb's pinching muscles, which are controlled by the median nerve.
Carpal tunnel syndrome occurs as a result of compression of the median nerve.
The median nerve runs from your forearm through a passageway in your wrist (carpal tunnel) to your hand. It provides sensation to the palm side of your thumb and fingers, with the exception of your little finger. It also provides nerve signals to move the muscles around the base of your thumb (motor function).
In general, anything that crowds, irritates or compresses the median nerve in the carpal tunnel space can lead to carpal tunnel syndrome. For example, a wrist fracture can narrow the carpal tunnel and irritate the nerve, as can the swelling and inflammation resulting from rheumatoid arthritis.
In many cases, no single cause can be identified. It may be that a combination of risk factors contributes to the development of the condition.
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.
- 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.
Tests and 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.
- 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.
Treatments and drugs
Carpal tunnel syndrome should be treated as early as possible after you begin to experience symptoms.
Some people with mild symptoms of carpal tunnel syndrome can ease their discomfort by taking more frequent breaks to rest their hands, avoiding activities that worsen symptoms and applying cold packs to reduce occasional swelling.
If these techniques don't offer relief within a few weeks, additional treatment options include wrist splinting, medications and surgery. Splinting and other conservative treatments are more likely to help you if you've had only mild to moderate symptoms for less than 10 months.
If the condition is diagnosed early, nonsurgical methods may help improve carpal tunnel syndrome. Methods may include:
Physiotherapy is beneficial for most carpal tunnel sufferers especially in mild to moderate cases.
Your physiotherapist will address:
- Carpal bone mobilisation and flexor retinaculum stretching to open the carpal tunnel. Tal-Akabi & Rushton (2000).
- Nerve and tendon gliding exercises to ensure full unrestricted nerve motion is available. McKeon & Hsieh (2008).
- Muscle and soft tissue extensibility. Moraska (2008).
- Cervicothoracic spine to correct any referral or double crush syndromes. Kwon et al (2006).
- Grip and pinch, thumb abduction and forearm strengthening in later phases. Pinar et al (2005).
- Comprehensive upper limb, wrist and hand ROM strengthening and endurance exercises.
- Posture, fine motor and hand dexterity exercises.
- 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.
- 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 carpal tunnel syndrome results from an inflammatory arthritis, such as rheumatoid arthritis, then treating the arthritis may reduce symptoms of carpal tunnel syndrome, but this hasn't been proved.
If your symptoms are severe or persist after trying nonsurgical therapy, surgery may be the most appropriate option.
The goal of carpal tunnel surgery is to relieve pressure on your median nerve by cutting the ligament pressing on the nerve.
The surgery may be performed with two different techniques. Discuss the risks and benefits of each technique with your surgeon before surgery. Surgery risks may include incomplete release of the ligament, wound infections, scar formation, and nerve or vascular injuries. The final results of endoscopic and open surgery are similar.