Carpal tunnel syndrome
- Carpal tunnel syndrome (CTS) is a disorder marked by weakness and pain in the hand and wrist. CTS occurs in the nerves of the hands -- not the muscles, as some people believe.
- It is not completely known how the process leading to carpal tunnel syndrome actually evolves, and how nerve conduction (the passing of the nerve signal) through the wrist changes.
- In general, carpal tunnel syndrome develops when the tissues around the median nerve swell and press on the nerve.
- Early in the disorder, the process is reversible. Over time, however, the insulation on the nerves may wear away, and permanent nerve damage may develop.
- CTS is associated with a family history of the disorder.
- Many studies indicate that women have a significantly higher risk for carpal tunnel syndrome than men do.
- Older people are at higher risk than younger adults.
- Workers who use their hands and wrists repetitively are at risk for CTS
According to a 2007 report from the Bureau of Labor Statistics, carpal tunnel syndrome was associated with the second longest average time away from work (28 days) among the major disabling diseases and illnesses in all private industries.
- It is critical to begin treating early phases of carpal tunnel syndrome before the damage progresses.
- A conservative approach to CTS, which may include corticosteroid injections and splinting, is the first step in treating this disorder.
- Surgery for CTS is among the most common hand surgeries.
- In various trials, 70 - 90% of patients who underwent surgery were free of nighttime pain afterward.
Carpal tunnel syndrome (CTS) is a disorder marked by weakness and pain in the hand and wrist. CTS occurs in the nerves of the hands -- not the muscles, as some people believe. The symptoms of CTS can be incapacitating.
The Carpal Tunnel and Median Nerve
To understand how carpal tunnel syndrome arises, it is important to know the parts of the hand and wrist that are involved.
The Carpal Tunnel. The carpal tunnel is a passageway that forms beneath the strong, broad transverse ligament. This ligament is a bridge that extends across the lower palm and connects the bones of the wrist (carpals) that form an arch below the tunnel.
The Median Nerve and Flexor Tendons. The median nerve and nine flexor tendons pass under the ligament bridge and through the carpal tunnel (similar to a river). They extend from the forearm and up into the hand:
- The flexor tendons are fibrous cords that connect the muscles in the forearm to the fingers (two to each finger) and one to the thumb. They allow flexing of the fingers and clenching of the fist.
- The median nerve plays two important roles. It supplies sensation to the palm to side of the thumb, index, middle, and ring fingers, and to the flexor tendons. It provides function for the muscles at the base of the thumb (the thenar muscle).
The Carpal Tunnel Syndrome Process
It is not completely known how the process leading to carpal tunnel syndrome actually evolves, and how nerve conduction (the passing of the nerve signal) through the wrist changes. In general, carpal tunnel syndrome develops when the tissues around the median nerve swell and press on the nerve. Early in the disorder, the process is reversible. Over time, however, the insulation on the nerves may wear away, and permanent nerve damage may develop.
The following events have been observed in the hands of people with carpal tunnel syndrome:
- The protective lining of tendons (called the tenosynovium) swells within the carpal tunnel. Some research suggests that this swelling is caused by build-up of fluid (called synovial fluid) under the lining. Synovial fluid lubricates and protects the tendons.
- The transverse ligament, the band of fibrous tissue that forms the roof over the median nerve, becomes thicker and broader.
- The swollen tendons and thickened ligament compress the median nerve fibers, just as stepping on a hose slows the flow of water through it. This compression reduces blood flow and oxygen supply to the nerve, and slows the transmission of nerve signals through the carpal tunnel. Some cases of carpal tunnel syndrome may be due to enlargement of the median nerve rather than compression by surrounding tissues.
The result is pain, numbness, and tingling in the wrist, hand, and fingers. Only the little finger is unaffected by the median nerve.
Symptoms of carpal tunnel syndrome usually progress gradually over weeks and months and sometimes years. Anyone with recurrent or persistent pain, numbness and tingling, or weakness of the hand should consult a doctor for a diagnosis. Symptoms often develop as follows:
- Initial symptoms include pain in the wrist and palm side hand. Symptoms commonly occur in both hands. (Even when only one hand is painful, the other hand often shows signs of nerve conduction abnormalities on testing.)
- Early on, the patient also usually reports numbness, tingling, burning, or some combination of symptoms on the palm side of the index, middle, and ring fingers. (Typically the fifth finger has no symptoms.) Such sensations may radiate to the forearm or shoulder.
- Over time, the hand may become numb, and patients may lose the ability to feel heat and cold. Patients may experience a sense of weakness and a tendency to drop things.
- Patients may feel that their hands are swollen even though there is no visible swelling. This symptom may actually prove to be an important indicator of greater CTS severity.
Symptoms may occur not only when the hand is being used but also at night when the patient is at rest. Even in cases where work is suspected as the cause, symptoms typically first occur outside of work. In fact, the disorder may be distinguished from similar conditions by pain occurring at night after going to bed.
Biological Causes. Carpal tunnel syndrome is considered an inflammatory disorder caused by repetitive stress, physical injury, or a medical condition. It is often very difficult, however, to determine the precise cause of carpal tunnel syndrome. No tests are available to identify a specific cause. Except in patients with certain underlying diseases, the biological mechanisms leading to carpal tunnel syndrome are unknown.
Working Conditions versus Medical Problems. Although some studies suggest that more than half of CTS cases are associated with workplace factors, there is no strong evidence of a cause and effect relationship. In fact, most studies now strongly suggest that carpal tunnel syndrome is primarily associated with medical or physical conditions such as diabetes, osteoarthritis, hypothyroidism, and rheumatoid arthritis. CTS also tends to occur in people with certain genetic or environmental risk factors. These risk factors include obesity, smoking, alcohol abuse, or significant mental stress. CTS sometimes has a familial risk, implying some type of genetic origin. When such susceptible people are subjected to repetitive hand or wrist work, the risk for CTS can become significant. CTS, then, is very likely to be due to a combination of factors that lead to nerve damage in the hand.
Work-Related Issues and Carpal Tunnel Syndrome
High Force and Vibration. Even though medical and physical conditions may be the initial culprits leading to CTS, certain working conditions are especially related to nerve damage -- if not to pure cases of CTS. Work that involves high force or vibration is particularly hazardous, as is repetitive hand and wrist work in cold temperatures.
In addition to CTS, other disorders of the hand and wrist result from these work-related movements. They include the following:
- Hand-arm vibration syndrome -- tingling and numbing that persist even after the vibration stops
- Cumulative trauma (repetitive stress) disorder
- Overuse syndromes
- Chronic upper limb pain syndrome
All of these problems are generally associated with repetitive and forceful use of the hands, resulting in damaged muscles and bones of the upper arms.
A number of medical conditions increase the risk for or even cause CTS. The main conditions associated with CTS are diabetes, hypothyroidism, rheumatoid arthritis, osteoarthritis, obesity, and pregnancy. Many of the underlying diseases that contribute to the development of CTS are also associated with more severe forms of CTS.
Diabetes. CTS is a very common feature of diabetic neuropathy, one of the major complications of diabetes. Neuropathy is decreased or distorted nerve function; it particularly affects sensation. Symptoms include numbness, tingling, weakness, and burning sensations, usually starting in the fingers and toes and moving up to the arms and legs. About 6% of patients with CTS have diabetes. Up to 85% of patients with type 1 diabetes develop CTS. Development of CTS symptoms is related to the patient's age, and the length of time they had diabetes.
Autoimmune Diseases. In autoimmune diseases, the body's immune system abnormally attacks its own tissue, causing widespread inflammation, which, in many cases, affects the carpal tunnel of the hand. Such autoimmune diseases include rheumatoid arthritis, systemic lupus erythematosus, and thyroiditis, which can lead to hypothyroidism.. Some experts believe that CTS may actually be one of the first symptoms in a number of these diseases. Studies also suggest that CTS patients with these disorders are more likely to have severe CTS that requires surgery.
Diseases that Affect Muscle and Bones. Arthritis, gout, and other medical conditions that damage the muscles, joints, or bones in the hand may cause changes that lead to CTS.
Structural Abnormalities. Inborn abnormalities in the bones of the hand, wrist, or forearm may contribute to CTS.
Chronic Kidney Insufficiency. People who undergo hemodialysis for chronic kidney damage often experience a build-up of a certain type of protein, called beta 2-microglobulin, in the hand. This build-up can result in CTS. The longer the person has been receiving hemodialysis, the greater the risk of CTS. Certain drugs and procedures (particularly one procedure called hemodiafiltration) are being investigated as having the potential to reduce microglobulin build-up. It is hoped such new methods will delay the need for carpal tunnel surgery in patients undergoing long-term hemodialysis.
Other Diseases. A number of other medical conditions may cause or increase susceptibility to CTS:
- Down syndrome
- Amyloidosis (a progressive disorder of the connective tissues)
- Acromegaly (a disease that leads to abnormally large hands and feet due to excessive growth hormone)
- Tumor on the median nerve (removal of the tumor often resolves the CTS in such cases)
Medications. According to case reports, a number of medications may increase the risk for temporary CTS. They include certain medications that affect the immune system (such as interleukin-2), and anticlotting drugs (such as warfarin). There has been conflicting evidence as to whether corticosteroids and hormone replacement therapy may increase the risk of CTS. More research is needed before a cause-and-effect association can be established.
Bone dislocations and fractures can narrow the carpal tunnel, thereby exerting pressure on the median nerve.
Hormonal fluctuations in women play a role in CTS. Such fluctuations may cause fluid retention and other changes that cause swelling in the body. Fluid retention is one reason that CTS may develop during pregnancy.
CTS is associated with a family history of the disorder. Many of these cases can be the result of physical characteristics or medical conditions associated with CTS, which also run in families. However, in one study, 17% of family clusters of CTS were not associated with any such medical conditions, suggesting the genetic factors may be important in some people. Carpal tunnel syndrome in young people most likely has a genetic component.
Other genetic factors that may contribute to this disorder include abnormalities in certain genes that regulate myelin, a fatty substance that serves as insulation for nerve fibers.
Evidence suggests that about 3% of women and 2% of men will be diagnosed with carpal tunnel syndrome during their lifetime, with peak prevalence in women older than 55. Still, determining how many people actually have CTS is very difficult. Many people report CTS symptoms and have normal test results. Other people have no symptoms and abnormal test results.
A large 2005 study of more than 1,000 patients found that the severity of CTS was mild in 42% of patients, moderate in 18%, and severe in 40%. On average, patients were about 48 years old. More than five times as many women then men participated in the study.
Older people are at higher risk than younger adults. CTS is very rare in children.
Many studies indicate that women have a significantly higher risk for carpal tunnel syndrome than men do. According to the National Institutes of Health, women are three times more likely than men to have carpal tunnel syndrome. The explanation for this greater risk is unknown, but it may be related to the smaller size of women's carpal tunnel.
Hormonal changes appear to play a major role in CTS.
In pregnant women, CTS may occur in both wrists. CTS that begins during pregnancy is not usually severe and persistent enough to require treatment. Although cases eventually go away on their own after delivery, symptoms may persist for 6 months or more.
CTS has also been shown to increase:
- After delivering a baby
- During menopause
Women are also at a much higher risk for autoimmune disorders than men are; such disorders are significantly linked to CTS.
Obesity and Lack of Fitness
Being overweight consistently turns up as a risk factor for CTS and may play a direct causal role on CTS. Greater body mass appears to reduce nerve flow speed into the hand. Obesity is also related to poor physical fitness, which may also increase risk. A 2005 analysis indicated that weight is strongly linked to the onset of CTS in patients under the age of 63 years, but may be a less important factor as they get older.
Specific Workers at Risk for CTS
Workers who use their hands and wrists repetitively are at risk for CTS, particularly if they work in cold temperatures and have factors or medical conditions that make them susceptible.
Computer Users and Typists. Repetitive typing and key entry has traditionally been associated with missing work due to CTS (as opposed to repetitive stress symptoms, which are unrelated to nerve impingement). The risk for CTS in this group, however, is still much lower than with occupations involving heavy labor. Although more than 10% of the computer users complain of CTS symptoms, the evidence implicating computer use as a major cause of CTS is weak.
Other Very High-Risk Workers. Workers in the meat and fish packing industries and those who assemble airplanes have the highest risk for CTS, according to one study. Meat packers complained of pain and loss of hand function as long ago as the 1860s. Even today, the incidence of carpal tunnel syndrome in the meat, poultry, and fish packing industries may be as high as 15%, and as high as 10% in automobile workers.
Musicians. Musicians are at very high risk for CTS and other problems related to the muscles and nerves in the hands, upper trunk, and neck. In one study, 20% reported CTS or other nerve disorders in the hands and wrists.
Highest to Lowest Numbers of CTS Events by Job. The following is a list of occupations published by the Bureau of Labor Statistics in 2006 rating workers with highest to lowest total numbers of CTS-related events:
- Laborers and freight, stock, and material, movers
- Customer service representatives
- First-line supervisors/managers of office and administrative support workers
- Janitors, maids, and housekeeping cleaners
- Food service managers
- First-line supervisors/managers of retail sales workers
- Automotive service technicians and mechanics
- Executive secretaries and administrative assistants
- Financial managers
- Sewing machine operators
- Truck drivers
- Office clerks
- Accounting and auditing clerks
- Welders, cutters, solderers, and brazers
- Sheet metal workers
- Packers and packagers
- Computer software engineers
- Inspectors, testers, sorters, samplers, and weighers
- Stock clerks and order fillers
- Tire repairers and changers
- Packaging and filling machine operators and tenders
SOURCES: Bureau of Labor Statistics, U.S. Department of Labor, November 2006
Workers' Compensation and CTS. The issues surrounding workers' compensation are particularly troubling in determining accurately whether labor conditions cause carpal tunnel pain. CTS is a major contributor to workers' compensation cases.
Psychosocial Factors in the Workplace. Studies indicate that psychosocial factors in the workplace, such as intense deadlines, a poor social work environment, and low levels of job satisfaction, are major contributors to carpal tunnel pain. Such psychosocial conditions are more likely to be important factors in contributing to CTS in office workers, although they also complicate the condition in workers whose work is primarily physical.
At Home and Play. People who intensively cook, knit, sew, do needlepoint, play computer games, do carpentry, or extensively use power tools are at increased risk for CTS. Long-distance cycling may make symptoms of carpal tunnel syndrome worse.
Other Physical Characteristics
Square Wrists. Some (but not all) studies have reported a higher risk for CTS in people with square wrists (the thickness and width are about the same) than in those with the more common rectangular wrists.
Palm Shape. In one study, patients with palms that were both shorter and wider than average, and who also had shorter third fingers, were more likely to have CTS than those without these hand characteristics.
Poor Upper Back Strength. Some researchers claim that poor upper back strength makes people more susceptible to poor posture and injuries in the upper extremities, including carpal tunnel syndrome.
Smoking and Alcohol Abuse
Cigarette smoking slows down blood flow, so that smokers have worse symptoms and slower recovery than nonsmokers do. Increased alcohol intake has been associated with CTS in people with other risk factors.
Poor nutrition, previous injuries, and stress can increase one's risk for carpal tunnel syndrome. In addition, high levels of so-called "bad" cholesterol (low-density lipoprotein, or LDL) have also been linked to an increased risk of CTS.
Carpal tunnel syndrome can range from a minor inconvenience to a disabling condition, depending on its cause and persistence and the individual characteristics of the patient. Many cases of CTS are mild, and when symptoms don't last long, they often resolve (disappear) on their own. Once a woman with pregnancy-associated CTS gives birth, for instance, the swelling in her wrists and other symptoms almost always subside. Proper treatment of other medical conditions that cause CTS can often help reduce wrist swelling.
In severe untreated cases, however, the muscles at the base of the thumb may whither, and loss of sensation may be permanent. CTS can become so crippling that people can no longer do their jobs or even perform simple tasks at home.
Psychological and Social Effects at Home
Carpal tunnel syndrome exacts a psychological toll. Anyone who cannot use their hands is likely to be depressed and suffer low self-esteem. People may suffer daily pain. In severe cases, they may be unable to perform ordinary tasks, such as driving a car or carrying groceries. And equally or even more distressing, they may have to give up enjoyable sports and hobbies.
Impact on Work and Livelihood
According to a 2007 report from the Bureau of Labor Statistics, carpal tunnel syndrome was associated with the second longest average time away from work (28 days) among the major disabling diseases and illnesses in all private industries. (Fractures were first, with an average of 30 days away.) Interestingly, in service-providing industries, the trend was reversed. CTS was responsible for the longest time away from work (average 28 days), followed by fractures (average 27 days). Despite these numbers, however, there is good news: the same report noted that the overall number of CTS cases decreased by 1,070.
Employees with CTS who try to work through the disorder often put more stress on the wrists to compensate for the weakness and pain. The end result is to make the condition worse and impair work performance.
Eventually, the worker with CTS may be forced to give up his or her livelihood. In one study, nearly half of all patients with CTS changed jobs within 30 months of an initial diagnosis. And because of the controversy surrounding the issue of carpal tunnel syndrome and workers compensation, it is not always certain that the worker will receive compensation payments.
Because many factors can contribute to carpal tunnel syndrome, there is no single mode of prevention. Treating any underlying medical condition is certainly important. Simple common sense may help minimize some risk factors predisposing a person to work-related CTS or other cumulative trauma disorders. A patient can learn how to adjust the work area, handle tools, or perform tasks in ways that put less stress on the hands and wrists. Proper posture and exercise programs to strengthen the fingers, hands, wrists, forearms, shoulders, and neck may help prevent CTS.
Many companies are now taking action to help prevent repetitive stress injuries. In a major survey, 84% reported that they were modifying equipment, tasks, and processes. Nearly 85% were analyzing their workstations and jobs, and 79% were buying new equipment. It should be stressed, however, that there has been no evidence that any of these methods can provide complete protection against CTS. The optimal corporate approach, if possible, is to reallocate workers suffering from repetitive stress injuries to other jobs.
Preventing CTS in Keyboard Workers
Altering the way a person performs repetitive activities may help prevent inflammation in the hand and wrist. Most of the interventions described below have been found to reduce repetitive motion problems in the muscles and tendons of the hand and arm. They may reduce the incidence of carpal tunnel syndrome, although there is no definite proof of this effect.
Replacing old tools with ergonomically designed new ones can be very helpful.
Rest Periods and Avoiding Repetition. Anyone who does repetitive tasks should begin with a short warm-up period, take frequent breaks, and avoid overexertion of the hand and finger muscles whenever possible. Employers should be urged to vary the tasks and work content of their employees.
Taking multiple "microbreaks" (about 3 minutes each) reduces strain and discomfort without decreasing productivity. Such breaks may include the following:
- Shaking or stretching the limbs
- Leaning back in the chair
- Squeezing the shoulder blades together.
- Taking deep breaths
Good Posture. Good posture is extremely important in preventing carpal tunnel syndrome, particularly for typists and computer users.
- The worker should sit with the spine against the back of the chair with the shoulders relaxed.
- The elbows should rest along the sides of the body, with wrists straight.
- The feet should be firmly on the floor or on a footrest.
- Typing materials should be at eye level so that the neck does not bend over the work.
- Keeping the neck flexible and head upright maintains circulation and nerve function to the arms and hands. One method for finding the correct head position is the "pigeon" movement. Keeping the chin level, glide the head slowly and gently forward and backward in small movements, avoiding neck discomfort.
Good Office Furniture. Poorly designed office furniture is a major contributor to bad posture. Chairs should be adjustable for height, with a supportive backrest. Custom-designed chairs, made for people who do not fit in standard chairs, can be expensive. However, the costs are often offset by the savings in medical expenses that follow injuries related to bad posture.
Voice Recognition Software. For CTS patients who must use a computer frequently, a variety of voice recognition software packages (ViaVoice, Voice Xpress, Dragon NaturallySpeaking, IListen) are now available, enabling virtually hands-free computer use.
Keyboard and Mouse Tips. Anyone using a keyboard and mouse has some options that may help protect the hands.
- The tension of the keys should be adjusted so they can be depressed without excessive force.
- The hands and wrists should remain in a relaxed position to avoid excessive force on the keyboard.
- A 2003 study suggested that mouse-use poses a higher risk than keyboard use. Replacing the mouse with a trackball device and the standard keyboard with a jointed-type keyboard are helpful substitutions.
- Wrist rests, which fit under most keyboards, can help keep the wrists and fingers in a comfortable position.
- Some people recommend keeping the computer mouse as close to the keyboard and the user's body as possible, to reduce shoulder muscle movement.
- The mouse should be held lightly, with the wrist and forearm relaxed. New mouse supports are also available that relieve stress on the hand and support the wrist.
- Some people cut their mouse pads in half to reduce movement.
Innovative keyboard designs may reduce hand stress:
- Alternative geometry keyboards (Microsoft Natural Keyboard, Apple Adjustable Keyboard) allow the user to adjust and modify hand positions as well as adjust key tension. Most have a split or "slanted" keyboard that places the wrists at an angle. Studies suggest they are useful in promoting a neutral position for the wrist.
- The continuous passive motion (CPM) keyboard lifts and declines gently and automatically every 3 minutes to break tension on the hands and wrist.
- A keyless keyboard (orbiTouch) is an innovative device that uses two domes. The typist covers the domes with their hands and slides them into different positions that represent letters.
Reducing Force from Hand Tools
The force placed on the fingers, hands, and wrists by a repetitive task is an important contributor to CTS. To alleviate the effect of force on the wrist, tools and tasks should be designed so that the wrist position is the same as it would be if the arms dangled in a relaxed manner at the sides.
- No task should require the wrist to deviate from side to side or to remain flexed or highly extended for long periods.
- The handles of hand tools such as screwdrivers, scrapers, paint brushes, and buffers should be designed so that the force of the worker's grip is distributed across the muscle between the base of the thumb and the little finger, not just in the center of the palm.
- People who need to hold tools (including pencils and steering wheels) for long periods of time should grip them as loosely as possible.
- In order to apply force appropriately, the ability to feel an object is extremely important. Tools with textured handles are helpful.
- If possible, people should avoid working at low temperatures, which reduces sensation in hands and fingers.
- Power tools and machines should be designed to minimize vibrations.
- Wearing thick gloves, when possible, may lessen the shock transmitted to the hands and wrists.
Hand and Wrist Exercises for Prevention of Carpal Tunnel Syndrome
Hand and wrist exercises may help reduce the risk of developing carpal tunnel syndrome. Isometric and stretching exercises can strengthen the muscles in the wrists and hands, as well as the neck and shoulders, improving blood flow to these areas. Performing the simple exercises described below for 4 - 5 minutes every hour may be helpful.
Exercises for Carpal Tunnel Syndrome
Exercise 3. (Wrist Circle)
Fingers and Hand
Forearms (stretching these muscles will reduce tension in the wrist)
Neck and Shoulders
Carpal tunnel syndrome is most accurately diagnosed using the patients' descriptions of symptoms, and electrodiagnostic tests that measure nerve conduction through the hand. If electrodiagnostic testing is not available, symptom descriptions and a series of physical tests are useful.
Diagnosing CTS, however, is not straightforward. Only a small fraction of patients exhibit all three factors necessary for a clear diagnosis:
- Classic CTS symptoms
- Specific physical findings
- Abnormal electrodiagnostic test results
Many people have abnormal electrodiagnostic test results without classic symptoms or any symptoms at all. Furthermore, about 15% of the population has symptoms consistent with CTS, but most do not show test results indicating the disorder.
Symptom Description and Severity
Many cases of CTS result from a combination of a medical problem exacerbated by repetitive stress factors at work. The patient should give the doctor a detailed history and description of any complaints, in any part of the body. The patient should report in detail any daily activities that require repetitive hand or wrist actions, abnormal postures, or other regular situations that could affect the nerves in the neck, shoulders, and hands. The patient should also report whether the symptoms are more likely to appear at night, or after particular tasks.
Questionnaires. The use of specific questionnaires that score results are quite accurate in assessing the severity of the condition.
Hand Diagram. A diagram of the hand and wrist, usually divided into six regions, is a very useful diagnostic tool. Patients are asked to indicate where their symptoms are, including pain, numbness, or tingling, by locating the affected areas on the diagram. They may also be asked to rate the severity of their symptoms. A diagnosis is probable if at least two of fingers 1, 2, or 3 have these symptoms, and if there is pain in or near the wrist. CTS is possible if at least one of these fingers has symptoms. It is unlikely if there are no symptoms in these fingers, the palm, or the wrist.
Ruling out Underlying Medical Disorders
One of the most important first steps in diagnosing CTS is to rule out any underlying medical disorders that may be contributing to the condition. Experts emphasize the need to fully examine patients presenting with symptoms of CTS. Relying only on CTS symptoms, and personal or work histories may result in the failure to detect (and thus properly treat) underlying medical conditions that could be serious. If the doctor suspects that an underlying medical condition may be exacerbating the symptoms of CTS, laboratory tests will be performed. Tests for thyroid disease and rheumatoid arthritis may be helpful. The doctor may take an x-ray, for example, to check for arthritis or fractured bones.
Arthritic Conditions. Arthritic conditions, including rheumatoid arthritis, gout, and osteoarthritis, can all cause pain in the hands and fingers that may mimic carpal tunnel disease. The treatment for these conditions, however, is different.
Muscle and Nerve Diseases. Any disease or abnormality that affects the muscles and nerves, including those in the spine, may produce symptoms in the hand that mimic carpal tunnel syndrome.
Ruling Out Other Cumulative Trauma Disorders
About 25% of patients with suspected work-related cumulative trauma or repetitive stress disorders have evidence of other conditions that resemble, but are not, carpal tunnel syndrome. A definitive diagnosis is often difficult. Most require treatments similar to those used for CTS: rest, immobilization, steroid injections, and even surgery if conservative treatment is unsuccessful.
Other Cumulative Trauma Disorders
The Median Nerve in Other Locations
Repetitive work can cause pressure on the median nerve in locations other than the wrist and can also affect other nerves in the arm and hand. The branch of the median nerve that runs through the palm of the hand can be damaged directly by repeated pounding or by the use of certain tools requiring a strong grip using the palm, such as needle-nosed pliers. The median nerve can also be pinched in the forearm.
Guyon Canal Syndrome (Commonly called ulnar tunnel syndrome)
The ulnar nerve can, like the median nerve, can be trapped as a result of repetitive stress. When this nerve is trapped, the condition is sometimes referred to as ulnar tunnel syndrome. It is more correctly known as Guyon canal syndrome, however, since this is the name of the passage through which the ulnar nerve passes.
General symptoms are similar to carpal tunnel syndrome, but patients experience loss of sensation in the ring and little finger and in the outer half of the palm. It can be a separate problem, although it commonly occurs with CTS. In such cases, release surgery for CTS usually also relieves the ulnar nerve entrapment.
The ulnar nerve can also be affected at the elbow.
De Quervain's Tenosynovitis
Tenosynovitis is swelling of the slippery covering of the tendons that move the thumb. When it causes pain on the side of the wrist and forearm right below the base of the thumb, it is known as De Quervain's tenosynovitis. (Finklestein's Test may help identify this. Make a fist that encloses the thumb, and bend the wrist sideways and down away from the thumb. If it causes pain, it is likely to be De Quervain's tenosynovitis.) It may be treated with splints or corticosteroid injections. In severe cases release surgery is effective.
Digital Flexor Tenosynovitis (Trigger or Snapping Finger)
Digital flexor tenosynovitis, commonly called trigger or snapping finger, is brought on when a tendon thickens, leaving the finger or thumb in a bent position. This disorder usually occurs when the tendons form a knot and may arise in those with hypothyroidism, diabetes, gout, rheumatoid arthritis, or connective tissue disorders. It can cause pain and a clicking sound when the trigger finger or thumb is bent and straightened. It can be effectively treated with corticosteroid injections.
Thoracic Outlet Syndrome
Thoracic outlet syndrome is caused by compression of nerves or blood vessels running down the neck into the arm. It can produce symptoms very similar to CTS. Other symptoms may include Raynaud's phenomenon (changes in sensation and temperature in the hand). The compression occurs at the first rib in the front of the shoulder. This may happen after an accident or simply from chronic slouching posture. A doctor may be able to diagnose the condition by detecting diminished blood flow in the arm as the patient raises the affected hand and turns his or her head toward the opposite side. Although the condition is uncommon, a correct diagnosis is important to differentiate it from CTS, since treatments differ. Surgery may be required to relieve pressure on the nerves and blood vessels.
Physical Assessment Tests for Carpal Tunnel Syndrome
The following findings are helpful in identifying carpal tunnel syndrome:
- Less sensitivity to pain where the median nerve runs through to the fingers
- Thumb weakness
- Inability to tell the difference between one and two sharp points on the fingertips (this is a late sign of carpal tunnel)
Flick Signal. One important and simple test of carpal tunnel is the "flick" signal:
- The patient is asked, "What do you do when your symptoms are worse?"
- If the patient responds with a motion that resembles shaking a thermometer, the doctor can strongly suspect carpal tunnel.
Testing for Thumb Weakness. Two questions are useful in determining thumb weakness:
- Can the thumb rise up from the plane of the palm?
- Can the thumb stretch so that its pad rests on the pad of the little finger pad?
Provocation Tests. Certain tests can produce symptoms:
- Phalen's Test. In Phalen's test, the patient rests the elbows on a table and lets the wrists dangle with fingers pointing down and the backs of the hands pressed together. If symptoms develop within a minute, CTS is indicated. (If the test lasts for more than a minute even patients without CTS may develop symptoms.) This test may be particularly important in determining the severity of CTS and assessing the results of treatment.
- Tinel's Sign. In the Tinel's sign test, the doctor taps over the median nerve to produce a tingling or mild shock-sensation.
- Pressure Provocation Test. The doctor presses over the carpal tunnel for 30 seconds to produce tingling or shock in the median nerve.
- Tourniquet Test. This test employs an inflatable cuff that applies pressure over the median nerve to produce tingling or small shocks.
Hand Elevation Test. The patient raises their hand overhead for 2 minutes to produce symptoms of CTS. The test was recently proven to be accurate and may provide useful information when combined with the Tinel's and Phalen's tests.
Electrodiagnostic tests analyze the electric waves of nerves and muscles. These tests can help detect median nerve compression in the carpal tunnel.
Electrodiagnostic tests are the best methods for confirming a diagnosis of CTS at this time. Doctors who perform these tests should be certified by the American Board of Electrodiagnostic Medicine, which uses rigorous standards in qualifying doctors. Specific electrodiagnostic tests, called nerve conduction studies and electromyography, are the most common ones performed: Nerve conduction tests can also detect causes of symptoms that mimic CTS but are caused by other problems, such as pinched nerves in the neck or elbow, or thoracic outlet syndrome.
- Nerve Conduction Studies. To perform nerve conduction studies, surface electrodes are first fastened to the hand and wrist. Small electric shocks are then applied to the nerves in the fingers, wrist, and forearm to measure how fast a signal travels through the nerves that control movement and sensation. Nerve conduction tests are fairly accurate when done on patients with more clear-cut symptoms of carpal tunnel syndrome. They are less accurate in identifying mild CTS, however. Patients should be sure their practitioners perform tests that compare a number of internal responses, not just routine testing that records only the responses of muscles located in the palm at the base of the thumb. They should also make sure the tests measure responses on the second or third fingers.
- Electromyography. To perform electromyography, a fine, sterile, wire electrode is inserted briefly into a muscle, and the electrical activity is displayed on a viewing screen. Electromyography can be painful and is less accurate than nerve conduction. Some experts question, in fact, whether it adds any valuable diagnostic information. They suggest it be limited to unusual cases or when other tests indicate that the condition is aggressive and may increase the risk for rapid, significant injury.
While electrodiagnostic studies are frequently done to confirm the diagnosis of carpal tunnel syndrome in patients with classic symptoms, they are also performed on patients with symptoms that do not point to carpal tunnel syndrome as clearly. Doctors must interpret test results in these patients more carefully.
Portable electrodiagnostic testing. Portable electronic devices are being evaluated for measuring nerve conductivity. They are relatively quick and easy to use on a large scale in an industrial facility. However, these devices are not well studied in clinical trials.
Limitations. Electrodiagnostic studies are not well standardized, and certain conditions can skew the results of either test:
- Obesity can slow the speed of electrical conduction.
- Women and the elderly normally have slower conduction times than younger adult men.
Ultrasound. Studies of ultrasound accuracy in CTS diagnosis yield mixed results. In addition, there are no accepted standard diagnostic criteria for carpal tunnel syndrome using ultrasound.
MRI. Magnetic resonance imaging (MRI) has been studied as a tool to evaluate the median nerve. It requires special expertise, has limited diagnostic accuracy, and is still too expensive for routine use. Electrodiagnostic tests remain the preferred method of diagnosis. MRI may be most effective for detecting any internal injuries, tumors, arthritis, or joint damage that might be causing the problem. It may also be valuable in selecting surgical candidates when electrodiagnostic tests produce unusual results or indicate more severe disease than expected. Additionally, an MRI may be useful for evaluating patients if surgery fails to bring relief.
It is critical to begin treating early phases of carpal tunnel syndrome before the damage progresses. A conservative approach to CTS, which may include corticosteroid injections and splinting, is the first step in treating this disorder. The conservative approach is most successful in patients with mild carpal tunnel syndrome.
Studies suggest that surgery is a better option for severe CTS. Surgery is also more likely to be necessary for patients with underlying conditions such as diabetes. Even among patients with mild CTS, there is a high risk of relapse. Some researchers are reporting better results when specific exercises for carpal tunnel syndrome are added to the program of treatments.
Limiting Movement. If possible, the patient should avoid activities at work or home that may aggravate the syndrome. The affected hand and wrist should be rested for 2 - 6 weeks. This allows the swollen, inflamed tissues to shrink and relieves pressure on the median nerve. If the injury is work related, the worker should ask to see if other jobs are available that will not involve the same hand or wrist actions. Few studies have been conducted on ergonomically designed furniture or equipment, or on frequent rest breaks. However, it is reasonable to ask for these if other work is not available.
Conservative Treatment Approach. The following conservative approaches have been shown to provide symptom relief:
- Wrist splints
- Corticosteroids (steroids). Injected or short-term oral corticosteroids may be tried if other methods fail.
A major analysis of other conservative approaches found that patients had no significant relief from nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs include common pain relievers such as aspirin and ibuprofen (Advil). The same report also found no benefits from diuretics, magnet therapy, laser acupuncture, vitamin B6, exercise, or chiropractic care. Other approaches being investigated include omega-3 fatty acid supplements.
Underlying Conditions. It is important to treat any underlying medical condition that might be causing carpal tunnel syndrome. For example, reducing inflammation in rheumatoid arthritis or other forms of inflammatory disorders that directly cause CTS is very helpful. Hypothyroidism and diabetes are diseases associated with an increased risk of CTS. The treatments for such diseases may offer some relief for CTS symptoms.
Wrist splints can keep the wrist from bending. They are not as beneficial as surgery for patients with moderate-to-severe CTS, but they appear to be helpful in specific patients, such as those with mild-to-moderate nighttime symptoms of less than a year's duration. In selected patients, up to 80% reported fewer symptoms, usually within days of wearing the splint.
Typically the splint is worn at night or during sports. The splint is used for several weeks or months, depending on the severity of the problem, and may be combined with hand and finger exercises. Benefits may last even after the patient stops wearing the splint.
Corticosteroid Injections. Corticosteroids (also called steroids) reduce inflammation. If restriction of activities and the use of painkillers are unsuccessful, the doctor may inject a corticosteroid into the carpal tunnel. Some experts recommend them for patients with CTS whose symptoms are intermittent, and there is no evidence of a permanent injury. In CTS, steroid injections (such as cortisone or prednisolone) shrink the swollen tissues and relieve pressure on the nerve. Evidence strongly suggests that they offer short-term relief in a majority of CTS patients. It should be noted that the pain may increase for a day or two after the injection, and skin color may change.
Unfortunately, in many cases, steroid injections provide only temporary relief (from 1 - 6 months), particularly in patients with more severe symptoms. Generally a second injection does not provide any added benefit. Another concern with use of these injections in moderate or severe disease is that nerve damage may occur even while symptoms are improving.
Corticosteroid injections are particularly useful for pregnant patients, as their symptoms often go away within 6 - 12 months after pregnancy.
Most doctors limit steroid injections to about three per year, since they can cause complications, such as weakened or ruptured tendons, nerve irritation, or more widespread side effects.
Low-Dose Oral Corticosteroids. Oral corticosteroids are medicines taken by mouth. Short-term (1 - 2 weeks), low-dose use of corticosteroids may provide long-term relief, but long-term use can cause serious side effects, including high blood pressure and high blood sugar levels. People with diabetes should be very cautious about oral corticosteroids.
Yoga and Other Exercise Programs
Yoga. Very limited evidence suggests that yoga practice may provide some benefit for patients with carpal tunnel syndrome. Yoga postures are designed to stretch, strengthen, and balance upper body joints.
General Exercise Program. Some experts have reported that people who are physically fit, including athletes, joggers, and swimmers, have a lower risk for cumulative trauma disorders. Although there is no evidence that exercise can directly improve CTS, a regular exercise regimen using a combination of aerobic and resistance training techniques strengthens the muscles in the shoulders, arms, and back, helps reduce weight, and improves overall health and well-being.
Ultrasound employs high-frequency sound waves directed toward the inflamed area. The sound waves are converted into heat in the deep tissues of the hand, opening the blood vessels and allowing oxygen to be delivered to the injured tissue. It is often performed along with nerve and tendon exercises. It is not yet known how effective ultrasound treatment is.
Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)
Nonsteroidal anti-inflammatory drugs (NSAIDs), which include aspirin and ibuprofen (Advil), are the most common pain relievers used for CTS. They block prostaglandins, the substances that dilate blood vessels and cause inflammation and pain. Unfortunately, as with most other medications used for carpal tunnel syndrome, there are few well-conducted studies to determine their role in CTS. To date, there is no evidence that they offer any significant relief, and regular use can have serious side effects. Therefore, they are generally not used for long-term treatment of carpal tunnel symptoms.
Other Conservative Approaches
Ice and Warmth. Ice may provide benefit for acute pain. Some patients have reported that alternating warm and cold soaks have been beneficial. (If hot applications relieve pain, most likely the problem is not caused by CTS but by another condition producing similar symptoms.)
Low-Level Laser Therapy. Some investigators are working with low-level laser therapy (LLLT), which generates extremely pure light in a single wavelength. The procedure is painless. Two trials comparing laser therapy to conservative treatment or a placebo laser treatment from no real benefit for this therapy.
Many alternative therapies are offered to sufferers of carpal tunnel syndrome and other repetitive stress disorders. Few, however, have any proven benefit. People should carefully educate themselves about how alternative therapies may interact with other medications or impact other medical conditions, and should check with their doctor before trying any of them.
Vitamin B6. Vitamin B6 (pyridoxine) is often used for carpal tunnel syndrome. Studies have not supported its benefits, however, either in oral or cream form. It should also be noted that excessively high doses of vitamin B6 can be toxic and cause nerve damage.
Acupuncture. A very limited amount of evidence shows that acupuncture may be useful as a supplement to standard treatment.
Chiropractic Therapies. Chiropractic techniques have been useful for some people whose condition is produced by pinched nerves. There is little evidence, however, to support its use for carpal tunnel syndrome.
Magnets. Magnets are a popular but unproven therapy for pain relief.
Botulinum toxin type A. Intracarpal injections of botulinum toxin type A (Botox) has not been well studied.
Every year more than 500,000 people in the US undergo surgeries for carpal tunnel syndrome. Surgery for CTS is among the most common hand surgeries. In various trials, 70 - 90% of patients who underwent surgery were free of nighttime pain afterward.
Candidates for Surgery
Although evidence strongly suggests that surgery is more effective than conservative approaches (at least in patients with moderate-to-severe CTS), the decision about whether to have surgery to correct CTS, and when to have it, is a troubling one for patients. Electrodiagnostic and other tests used to confirm the presence of CTS are not very useful in determining the best candidates for surgery. Severe CTS may not relate at all to surgical success or the lack of it.
In general, patients with the following characteristics are less likely to respond to conservative treatment and, therefore, might benefit from surgery:
- Symptoms lasting 10 months or longer
- Continual numbness
- Muscles in the base of the palm have begun to shrink
- Symptoms occur within 30 seconds during a Phalen's test
- Above 50 years of age
Surgery does not cure all patients, and because it permanently cuts the carpal ligament, some wrist strength may be lost, but it rarely has any effect on function. A number of experts believe that release surgery is performed too often. They recommend aggressive conservative treatment (such as splints, anti-inflammatory agents, and physical therapy) before choosing surgery. Nevertheless, other experts argue that CTS is often progressive and will worsen over time without surgery. Furthermore, evidence now shows that surgery is better than splints and conservative measures for the relief of pain.
Factors that may increase the chances for successful surgery:
- Having surgery performed within 3 years of the diagnosis of the disorder
- Being in good general health
- Having very slow nerve conduction results, but also having some muscle strength before surgery
- Symptoms are worse at night than during the day
Factors that may reduce the chances for success:
- Having very severe symptoms before surgery.
- Performing heavy manual labor, particularly working with vibrating tools. Medical evidence has found that only slightly more than half the people who used vibrating hand-held tools were symptom-free 3 years after a CTS operation.
- Having very poor nerve conduction results before surgery. However, some patients with severe symptoms, who have normal neurological and physical test results, could still experience significant relief from CTS surgeries.
- Patients who are on hemodialysis have good initial success, but the condition deteriorates in about half of them after around a year and a half.
- Alcohol abuse can negatively affect the results of CTS surgery.
- Poor mental health can lead to less successful surgery.
- Patients with diabetes and high blood pressure may be more likely to require a second operation.
Standard Release Surgical Procedures
Open Release Surgery. Traditionally, surgery for CTS entails an open surgical procedure performed in an outpatient facility. In this procedure, the carpal ligament is cut free (released) from the median nerve. The pressure on the median nerve is therefore relieved. The surgery is straightforward.
The Mini-Open Approach. In recent years, more surgeons have adopted a "mini" open -- also called short-incision -- procedure. This surgery requires only a one-inch incision, but it still allows a direct view of the area (unlike endoscopy, which is viewed on a monitor). The mini-open approach may allow for quicker recovery while avoiding some of the complications of endoscopy, although few studies have investigated its benefits and risks. The recovery time in patients receiving the mini-open approach may be shorter than with the open approach, and results are generally the same.
Endoscopy. Endoscopy for carpal tunnel syndrome is a less invasive procedure than standard open release.
- A surgeon makes one or two 1/2-inch incisions in the wrist and palm, and inserts one or two endoscopes (pencil-thin tubes).
- The surgeon then inserts a tiny camera and a knife through the lighted tubes.
- While observing the underside of the carpal ligament on a screen, the surgeon cuts the ligament to free the compressed median nerve.
Patients report less pain than those who had the open release procedure, and return to normal activities in about half the time. Nevertheless, at this time the best evidence available does not show any significant long-term advantages of endoscopy over open release in terms of muscle, grip strength, or dexterity. The endoscopic approach may even carry a slightly higher risk of pain afterward. This may be due to a more limited view of the hand with endoscopy. (In the open release procedure, the surgeon has a full view of the structures in the hand.) Concerns of irreversible nerve injury with endoscopic carpal tunnel release, when compared with open carpal tunnel release, exist because of this reduced visibility. However, larger studies have shown an extremely low number of complications following the procedure, when performed by physicians experienced in the technique.
Recovery after Surgery
Timing for Recovery. Patients should expect the following course:
For some patients, release surgery relieves CTS symptoms of numbness and tingling immediately.
- People who have the operation on both hands are completely incapacitated for about 2 weeks and must have someone to help them at home.
- Returning to strenuous work right after surgery may cause the symptoms to return. Patients generally stay out of work for at least a month and often much longer, depending upon the type of surgery and the severity of the condition. Recovery time appears to be faster with endoscopy than with open release.
- Immediately after surgery patients usually experience a decline in grip strength and dexterity. Studies have reported a wide range of recovery in this area. The scar may remain tender for up to a year.
- Peak improvement (the best level of improvement a patient can reach) may take a long time (up to 10 months).
Physical Therapy. Physical therapy following surgery has not been shown to speed up recovery or affect the final outcome of CTS surgery.
Complications and Long-Term Outcome
Treatment failure and complication rates of CTS surgery vary.
Complications after surgery may include the following:
- Nerve damage with tingling and numbness (usually temporary)
- Loss of some wrist strength is a complication that affects 10% to a third of patients. Endoscopy may have better results than open release. Some patients who have jobs requiring significant strength of the hand and wrist may not be able to perform them after surgery. These workers may also have problems in other parts of the upper body, including elbows and shoulders. These problems do not go away with surgery and can persist. Studies indicate that 10 - 15% of patients change jobs after a CTS operation.
If pain and symptoms return, the release procedure may be repeated.
Reasons for procedure failure include:
- Incomplete release of the ligament
- Extensive scarring
- Recurrence of the disorder due to underlying medical conditions
Patients who had open release surgery appear more likely to require repeat operations compared with those who have had endoscopic surgery.
- www.aanem.org -- Advancing Association of Neuromuscular and Electrodiagnostic Medicine
- www.apta.org -- American Physical Therapy Association
- www.aoec.org -- The Association of Occupational and Environmental Clinics
- www.aaos.org -- American Academy of Orthopaedic Surgeons
- www.assh.org -- American Society for Surgery of the Hand
- www.ampainsoc.org -- American Pain Society
- www.iasp-pain.org -- Association for the Study of Pain
- www.aan.com -- American Academy of Neurology
- www.nih.gov/niams -- National Institute of Arthritis and Musculoskeletal and Skin Diseases
- www.ninds.nih.gov -- National Institute of Neurological Disorders and Stroke
- www.nlm.nih.gov/medlineplus/carpaltunnelsyndrome.html -- Information on CTS
- www.cdc.gov/niosh/homepage.html -- National Institute for Occupational Safety and Health
- www.workerscompensationinsurance.com -- Resources for injured workers
- www.keybowl.com -- orbiTouch keyboard
- www.ergodevices.com -- Hand and wrist support keyboard
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Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.