Carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common nerve entrapment disorder. It involves narrowing of a passage in the wrist called the carpal tunnel. This constricted tunnel presses on or pinches the median nerve and causes chronic pain in the wrist and hand.

The median nerve controls sensation in the palm side of the thumb, index finger, middle finger and part of the ring finger, as well as the impulses to some small muscles in the hand that allow the fingers and thumb to move.

The carpal tunnel receives its name from the eight bones in the wrist, called carpals, that form a structure resembling a tunnel or canal. The carpal ligament wraps around this passage. In addition to accommodating the median nerve, the carpal tunnel also contains blood vessels, connective tissue and flexor tendons, which control flexion (bending) of the fingers.

Carpal tunnel syndrome (CTS) is the most common nerve entrapment disorder. It involves narrowing of a passage in the wrist called the carpal tunnel. This constricted tunnel presses on or pinches the median nerve and causes chronic pain in the wrist and hand.

The median nerve controls sensation in the palm side of the thumb, index finger, middle finger and part of the ring finger, as well as the impulses to some small muscles in the hand that allow the fingers and thumb to move.

The carpal tunnel receives its name from the eight bones in the wrist, called carpals, that form a structure resembling a tunnel or canal. The carpal ligament wraps around this passage. In addition to accommodating the median nerve, the carpal tunnel also contains blood vessels, connective tissue and flexor tendons, which control flexion (bending) of the fingers.

Carpal tunnel syndrome (CTS) is a progressively painful condition. It often results from a combination of factors that increase pressure on the median nerve (which help controls sensations and movement in the hand and fingers) and tendons in the carpal tunnel (tunnel-like structure of bones and ligaments in the wrist), rather than a problem with the nerve itself.

In most cases, the exact cause of CTS is unknown. However, several risk factors have been associated with the disorder, including:

A higher incidence of CTS has been noted in patients who have one or more of a wide range of diseases, including:

• Rheumatoid arthritis (RA). A debilitating inflammatory disease that causes pain, swelling, stiffness and loss of function in the joints. RA patients may be at higher risk for developing CTS. However, in many cases, the symptoms of median nerve compression resolve as the rheumatoid arthritis is treated.
• Gout. A form of arthritis caused by the buildup of uric acid crystals in the joints, causing inflammation, swelling and pain. The joint swelling in gout patients may predispose them to CTS.
• Osteoarthritis. The most common form of arthritis, which can affect the wrist.
• Lupus. An inflammatory autoimmune disorder that can affect the skin, joints and internal organs. The joint inflammation associated with lupus may put patients at an increased risk for developing CTS.
• Acromegaly. A rare endocrine disorder in which the pituitary gland produces excess growth hormone. Patients experience overgrowth of bone and cartilage, which can lead to CTS. In most cases, treatment for acromegaly usually leads to rapid resolution of CTS.
• Diabetes. Diabetic patients may be at higher risk for CTS because diabetes makes the nerves more susceptible to compression and impingement.
• Hypothyroidism. An underactive thyroid gland, often caused by thyroiditis (inflammation of the gland). CTS may be associated with this thyroid disorder because hypothyroid patients tend to retain fluid in their connective tissues due to an accumulation of mucopolysaccharides, substances that accumulate abnormally in hypothyroidism. This exacerbates the swelling and worsens the compression of the median nerve. Less commonly, CTS may develop in patients with hyperthyroidism (overactive thyroid).
• Sarcoidosis. A disease of unknown cause that is characterized by widespread lesions in the body.
• Amyloidosis. A condition in which proteins are deposited in tissues and organs.
• Fibromyalgia. A chronic disorder that causes muscle pain and fatigue. Studies suggest that CTS can occur, and is frequently unrecognized, in fibromyalgia patients. However, the overall incidence of CTS in fibromyalgia patients might not be different from that of the general population.

CTS is also associated with the type of trauma that causes hand-arm vibration syndrome (HAVS) and can coexist with the disorder. HAVS results from prolonged exposure to vibration, specifically to the hands and forearms while using certain types of vibrating tools (e.g., jackhammers, power chain saws). The symptoms of HAVS are similar to CTS and include numbness, tingling and loss of nerve sensitivity.

In most cases, carpal tunnel syndrome (CTS) begins slowly, with a slight aching of the wrist that extends to the hand or forearm. This pain initially may be felt only at night. One or both wrists may be involved. Other common signs and symptoms include:

• Tingling and/or numbness of the fingers and/or hand. The thumb, index, middle and ring fingers are affected, but the median nerve does not serve the pinky. Sensations of tingling and numbness are more apparent while engaging in certain activities, such as driving a vehicle or holding a phone or other object. To relieve this symptom, many people shake out their hands.
• Radiating wrist pain. Pain that radiates or extends from the wrist up the arm to the shoulder or down into the palm or fingers is a symptom of CTS. This is especially common after forceful or repetitive use. In most instances, this occurs on the palm side of the forearm.
• Weakness of the hands or a tendency to drop objects, even if they are not heavy, in cases of advanced CTS.
• Permanent loss of feeling in some fingers. This can occur if CTS is advanced.

To diagnose carpal tunnel syndrome (CTS), the physician will review the patient’s medical history and perform a physical examination. In learning about the medical history, the physician will ask about any conditions that may be associated with CTS, such as pregnancy, diabetes, hypothyroidism or rheumatoid arthritis.

The physician will also inquire about any recent accidents or injuries involving the wrist, hand or arm that may be causing CTS. In addition, the physician will ask about any activities the patient engages in that might contribute to CTS, such as typing, playing a musical instrument or using power tools.

During the physical exam, the physician will test the feeling in the fingers and the strength of the muscles in the hand because these can be affected by CTS. The physician will also examine the neck, shoulder and elbow also to determine the possible level of nerve entrapment. In many patients, applied pressure on the median nerve in the wrist – by either bending the wrist (Phalen's sign), tapping on the nerve (Tinel's sign) or just pressing on it – can bring about the symptoms.

To confirm a diagnosis of CTS, a physician may order further tests, which may include:

Researchers in 2007 reported finding biomarkers (chemicals in the body) that may be an early signal of CTS. The discovery could one day lead to a test that allows improved diagnosis and prevention of the condition.

Left untreated, carpal tunnel syndrome (CTS) can ultimately lead to permanent atrophy (wasting) of the hand muscles. Treatment for CTS with a physician specializing in the disorder should begin as soon as possible to avoid permanent damage to the median nerve, one of the nerves that control hand and finger movement and sensation.

Physicians will treat any underlying causes of CTS first (e.g., diabetes, hypothyroidism, rheumatoid arthritis). In some cases, symptoms (pain, tingling and numbness in the arm, hand and/or wrist) improve with treatment of the underlying cause.

Initial treatment of CTS generally involves resting the affected hand and wrist for up to two weeks, avoiding activities that might exacerbate symptoms (e.g. knitting, use of power tools) and applying cool packs (cryotherapy) to reduce swelling.

For those whose jobs involve extensive hand movement, a physician may recommend the use of an elastic glove. Also, a physician may recommend strength and stretching exercises to maintain wrist strength and mobilize nerves and tendons.

In addition, studies sponsored by the National Institutes of Health indicate that yoga and acupuncture may also help relieve CTS pain.

If these techniques do not work, a physician may recommend:

Surgery may be recommended for CTS patients whose symptoms are severe or after other noninvasive treatments have failed to show improvement for at least six months. Carpal tunnel release is one of the most common surgical procedures in the United States. There are three types of carpal tunnel release procedures, and all involve severing the band of tissue around the wrist to reduce the pressure on the median nerve:

After carpal tunnel release surgery, pain, tingling and numbness typically improve within six weeks. Weakness and functionality improve more gradually. Grip and pinch strength may worsen at first, then return to preoperative levels in about three months, and improve significantly by two years. Studies indicate that the majority of CTS patients who undergo surgery are very satisfied with the results.

To promote recovery after surgery, physicians may recommend that patients avoid alcohol, tobacco and exposure to any type of repetitive, forceful activities involving the use of the hand or fingers. Studies indicate that CTS patients who smoke take longer to recover from carpal tunnel release.

Rarely, there may be complications after carpal tunnel release surgery. For example, some patients may experience infection, nerve damage, stiffness and pain at the scar. In a few cases, the wrist may lose strength because the carpal ligament is cut. In such cases, physicians may recommend occupational therapy or physical therapy, preferably from a certified hand therapist (CHT), to restore wrist function.

After recovery from surgery, some patients may need to adjust their job duties or, if necessary, change jobs.

After treatment, recurrence of CTS is rare, and most patients recover completely, according to the National Institutes of Health. In addition, most CTS patients recover with conservative (noninvasive) treatment, and less than a third of patients require surgery.

Use of proper body mechanics, posture and ergonomics can reduce the risk of carpal tunnel syndrome (CTS). People can take several precautions to protect their hands, including:

• Reducing force and relaxing the grip. Most people use more force than necessary to grasp objects or perform tasks involving the hands.
• Taking frequent breaks. Individuals may benefit from taking breaks every 15 to 20 minutes and gently stretching and bending the hands and wrists. Whenever possible, they should alternate tasks. If using vibrating tools or machinery, which requires a great amount of force, taking breaks is very important. In addition, it is recommended that workers who perform such hand-intensive tasks stretch at the start of work.
• Using proper form and posture. Avoid bending the wrist all the way down or up. A relaxed midpoint position is best. If using a computer, make sure the keyboard is at a height that allows the wrist to rest comfortably without having to bend at a sharp angle. It also helps to keep the elbows close to the sides when typing to reduce the strain on the forearm. In addition, incorrect posture can cause the shoulders to roll forward. When the shoulders are stooped forward, the neck and shoulder muscles are shortened, which compresses the nerves in the neck – all of which can affect the wrists, hands and fingers.
• Keeping hands warm. A person is more likely to develop hand pain and stiffness if working in a cold environment. In cases where this cannot be avoided, use fingerless gloves that keep the hands and wrists warm.