|Carpal tunnel syndrome|
|Classification and external resources|
Transverse section at the wrist. The median nerve is colored yellow. The carpal tunnel consists of the bones and flexor retinaculum.
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Carpal tunnel syndrome (CTS), or median neuropathy at the wrist, is a medical condition in which the median nerve is compressed at the wrist, leading to paresthesias, numbness and muscle weakness in the hand. Night symptoms and waking up at night is a characteristic of established carpal tunnel syndrome. They can be managed effectively with night-time wrist splinting in most patients.
The definitive treatment for carpal tunnel syndrome is carpal tunnel release surgery. This is effective at relieving symptoms and preventing further nerve damage, but established nerve dysfunction in the form of static (constant) numbness, atrophy, or weakness are usually permanent.
Most cases of CTS are idiopathic (without a specific cause). Some patients are genetically predisposed to develop the condition.
The diagnosis of CTS is often misapplied to patients who have activity-related arm pain, such as repetitive strain injury (RSI).
Although the condition was first noted in medical literature in the early 20th century, the first use of the term “carpal tunnel syndrome” was in 1939. The pathology was identified by physician Dr. George S. Phalen of the Cleveland Clinic after working with a group of patients in the 1950s and 1960s. CTS became widely known among the general public in the 1990s because of the rapid expansion of office jobs.
The median nerve passes through the carpal tunnel, a canal in the wrist that is surrounded by bone on three sides, and a transverse carpal ligament on the fourth. Nine tendons—the flexor tendons of the hand—pass through this canal. The median nerve can be compressed by a decrease in the size of the canal, an increase in the size of the contents (such as the swelling of lubrication tissue around the flexor tendons), or both. Simply flexing the wrist to 90 degrees will decrease the size of the canal.
Compression of the median nerve as it runs deep to the transverse carpal ligament (TCL) causes wasting of the thenar eminence, weakness of the flexor pollicis brevis, opponens pollicis, abductor pollicis brevis, as well as sensory loss in the distribution of the median nerve distal to the transverse carpal ligament. There is a superficial sensory branch of the median nerve, which branches proximal to the TCL and travels superficial to it. This branch is therefore spared, and it innervates the palm towards the thumb.
Many people who have carpal tunnel syndrome have gradually increasing symptoms over time. The first symptoms of CTS may appear when sleeping, and typically include numbness and paresthesia (a burning and tingling sensation) in the thumb, index, and middle fingers, although some patients may experience symptoms in the palm as well. These symptoms appear at night because people tend to bend their wrists when they sleep, which further compresses the carpal tunnel.
Patients may note that they "drop things". It is unclear if carpal tunnel syndrome creates problems holding things, but it does decrease sweating, which decreases friction between an object and the skin.
In early stages of CTS individuals often mistakenly blame the tingling and numbness on restricted blood circulation. They may also be at ease and accepting of the symptoms and believe their hands are simply “falling asleep”. In chronic cases, there may be wasting of the thenar muscles (the body of muscles connected to the thumb), weakness of palmar abduction of the thumb (difficulty bringing the thumb away from the hand).
Unless numbness or paresthesia are among the predominant symptoms, it is unlikely the symptoms are primarily caused by carpal tunnel syndrome. In effect, pain of any type, location, or severity with the absence of significant numbness or paresthesia is not likely to fall under this diagnosis.
Carpal tunnel syndrome can be misdiagnosed, and other syndromes can be misdiagnosed as carpal tunnel syndrome. A nerve conduction study or referral to a neurologist may be of benefit in clarifying the diagnosis.
The international debate regarding the relationship between CTS and repetitive motion in work is ongoing. The Occupational Safety and Health Administration (OSHA) has adopted rules and regulations regarding cumulative trauma disorders. Occupational risk factors of repetitive tasks, force, posture, and vibration have been cited. However, the American Society for Surgery of the Hand (ASSH) has issued a statement that the current literature does not support a causal relationship between specific work activities and the development of diseases such as CTS.
The relationship between work and CTS is controversial; in many locations workers diagnosed with carpal tunnel syndrome are entitled to time off and compensation. Carpal tunnel syndrome results in an average of $30,000 in lifetime costs (medical bills and lost time from work).
Some speculate that carpal tunnel syndrome is provoked by repetitive jacking and manipulating activities and that the exposure can be cumulative. It has also been stated that symptoms are commonly exacerbated by forceful and repetitive use of the hand and wrists in industrial occupations, but it is unclear if this refers to pain (which may not be due to carpal tunnel syndrome) or the more typical numbness symptoms.
A review of available scientific data by the National Institute for Occupational Safety and Health (NIOSH) indicated that job tasks that involve highly repetitive manual acts or specific wrist postures were associated with incidents of CTS, but causation was not established, and the distinction from work related arm pains that are not carpal tunnel syndrome was not clear. It has been proposed that repetitive use of the arm can affect the biomechanics of the upper limb or cause damage to tissues. It has also been proposed that postural and spinal assessment along with ergonomic assessments should be included in the overall determination of the condition. While addressing these factors has been found to improve comfort in some studies, there is no evidence that they affect the natural history of carpal tunnel syndrome.
Non-traumatic causes generally happen over a period of time, and are not triggered by one certain event. Many of these factors are manifestations of physiologic aging.
The common causes of carpal tunnel syndrome can be remembered using the mnemonic, MEDIAN TRAP for Myxoedema, Edema, Diabetes mellitus, Idiopathic, Acromegaly, Neoplasm, Trauma, Rheumatoid arthritis, Amyloidosis and Pregnancy.
The reference standard for the diagnosis of carpal tunnel syndrome is electrophysiological testing. Patients with intermittent numbness in the distribution of the median nerve and positive Phalen's and Durkan's tests, but normal electrophysiological testing have—at worst—very mild carpal tunnel syndrome. A predominance of pain rather than numbness is unlikely to be due to carpal tunnel syndrome no matter the result of electrophysiological testing.
Clinical assessment by history taking and physical examination can support a diagnosis of CTS.
Other conditions may also be misdiagnosed as carpal tunnel syndrome. Thus, if history and physical examination suggest CTS, patients will sometimes be tested electrodiagnostically with nerve conduction studies and electromyography. The goal of electrodiagnostic testing is to compare the speed of conduction in the median nerve with conduction in other nerves supplying the hand. When the median nerve is compressed, as in CTS, it will conduct more slowly than normal and more slowly than other nerves. There are many electrodiagnostic tests used to make a diagnosis of CTS, but the most sensitive, specific and reliable test is the Combined Sensory Index (also known as Robinson index).
A 2007 study conducted by the Department of Orthopaedic Surgery at Massachusetts General Hospital states that carpal tunnel syndrome is primarily determined by genetics and structure. Therefore, carpal tunnel syndrome is probably not preventable. However, others think it is preventable by developing healthy habits like avoiding repetitive stress, practicing healthy work habits like using ergonomic equipment and taking proper breaks, and early passive treatment like taking turmeric (anti-inflammatory), omega-3 fatty acids, and B vitamins. Those who favor activity as a cause of carpal tunnel syndrome speculate that activity-limitation might limit the risk of developing carpal tunnel syndrome, but there is little or no data to support these concepts and they stigmatize arm use in ways that risks increasing illness.
There have been numerous scientific papers evaluating treatment efficacy in CTS. It is important to distinguish treatments that are supported in the scientific literature from those that are advocated by any particular device manufacturer or any other party with a vested financial interest. Generally accepted treatments, as described below, may include splinting or bracing, steroid injection, activity modification, physical or occupational therapy (controversial), medications, and surgical release of the transverse carpal ligament.
A wrist splint helps limit numbness by limiting wrist flexion. Night splinting helps patients sleep. There is no evidence that wrist splinting is disease modifying.
The importance of wrist braces and splints in the carpal tunnel syndrome therapy is known, but many people are unwilling to use braces. In 1993, The American Academy of Neurology recommend a non-invasive treatment for the CTS at the beginning (except for sensitive or motor deficit or grave report at EMG/ENG): a therapy using splints was indicated for light and moderate pathology. Current recommendations generally don't suggest immobilizing braces, but instead activity modification and non-steroidal anti-inflammatory drugs as initial therapy, followed by more aggressive options or specialist referral if symptoms do not improve.
Newer types of treatments are emerging which are both palliative and physiologically modifying. These are active medical devices. While braces or splints have been used palliatively, the newer designs attempt to influence the pathophysiology of carpal tunnel syndrome and attempt to reverse its causes.
The newest of these is the Carpal Therapist which is an electrically powered massaging device worn on the wrist and arm. The principle is that manipulative therapy, which is generally effective in alleviating symptoms of carpal tunnel syndrome, can be reproduced mechanically. Therefore, deep tissue massaging is produced by the device in a particular pattern in order to attenuate the tendons and to drain interstitial fluid from the inflamed carpal tunnel. This combined effect reduces the pressure inside the carpal tunnel and therefore alleviates the symptoms caused by median nerve compression.
Another active medical device is The Carpal Solution. It is composed of a series of adhesive tape strips, which, when applied in a certain orientation, reportedly initiates stretching and re-shaping of the wrist’s anatomy. The re-shaping produces less strain inside the carpal tunnel, and therefore relieves the pressure on the median nerve.
Yet another device called WristTrac is a brace with a built-in traction system. The hand is placed into the brace and a knob is used to manually increase tension (traction) on the wrist. This presumably results in stretching of the wrist tendons, which in turn attenuates them within the carpal tunnel. It is thought that this results in less inflammatory pressure and therefore reduced pain.
Steroid injections can be quite effective for temporary relief from symptoms of CTS for a short time frame while a patient develops a longterm strategy that fits with his/her lifestyle. In certain patients, an injection may also be of diagnostic value. This treatment is not appropriate for extended periods, however. In general, medical professionals only prescribe local steroid injections until other treatment options can be identified. For most patients, surgery is the only option that will provide permanent relief.
There is little evidence to support the use of physiotherapy or occupational therapy techniques for carpal tunnel syndrome. They seem to be oriented primarily towards non-specific activity related pain rather than the numbness of carpal tunnel syndrome. The following comments regarding physical therapy seem to apply more to such chronic activity related pains than to verifiable idiopathic median nerve compression at the carpal tunnel.
Physiotherapy offers several ways to treat and control carpal tunnel syndrome. This procedure should be directed specifically towards the pattern of pain / symptoms and dysfunction assessed by the therapist. As such, it may include a range of modalities ranging from soft tissue massage, conservative stretches and exercises and techniques to directly mobilize the nerve tissue. It can also include the aforementioned immobilizing braces.
Clinically, sometimes a patient will present with a hand that is very inflamed and swollen with severe symptoms of pain, tingling and numbness and almost a fear of use because of the pain. In these cases a physiotherapist may focus on techniques to reduce the pain and inflammation, and exercises to encourage improved circulation. A comprehensive review of effectiveness of hand therapies in carpal tunnel management demonstrates that there is some valid scientific evidence for a range of therapeutic modalities. For instance, Body Awareness Therapy such as the Feldenkrais method has positive effects in relation to fibromyalgia and chronic pain. Structured exercise programs using these therapies to reduce wrist pain have been developed.
Occupational therapy offers ergonomic suggestions to prevent worsening of the symptoms. Occupational therapies facilitate hand function through remedial adaptive approaches.
Any forceful and repetitive use of the hands and wrists can cause upper extremity pain. More frequent rest can be useful if it can be orchestrated into one's schedule. It has been shown that taking multiple mini-breaks during the stressful activity is more effective than taking occasional long breaks. There are computer applications that aid users in taking breaks. All of these applications have recommended defaults, following the most effective average break configuration—a 30 sec. pause every 3 to 5 minutes (the more severe the pain, the more often one should take this break). There are also programs that automatically click the mouse. Before investing in these types of programs, it's best to consult with a doctor and research whether computer use is causing or contributing to the symptoms, as well as getting a formal diagnosis.
More pro-active ways to reduce stress on the wrists, which alleviates wrist pain and strain, involve adopting a more ergonomic work and life environment. Switching from a QWERTY computer keyboard layout to a more optimised ergonomic layout such as Dvorak was commonly cited as beneficial in early CTS studies, however some meta-analyses of these studies claim that the evidence that they present is limited.
It is also important that one's body be aligned properly with the keyboard. This is most easily accomplished by bending ones elbows to a 90 degree angle and making sure the keyboard is at the same height as the elbows. Also it is important not to put physical stress on the wrists by hanging the wrist on the edge of a desk, or exposing the wrists to strong vibrations (e.g. manual lawn mowing). Position the computer monitor directly in front of your seat, so the neck is not twisted to either side when viewing the screen.
Exercises that relax and strengthen the muscles of the upper back can reduce the risk of a double crush of the median nerve.
Massage is one of the most overlooked methods for treatment of the symptoms of CTS. The use of myofascial release and active stretch release can erase the pain, numbness, tingling and burning in minutes. Then following up with the stretches and exercises afore mentioned will lengthen the relief attained by these release techniques.
Using an over-the-counter anti-inflammatory such as aspirin, ibuprofen or naproxen can be effective as well for controlling symptoms. Pain relievers like paracetamol will only mask the pain, and only an anti-inflammatory will affect inflammation. Non-steroidal anti-inflammatory medications theoretically can treat the swelling and thus the source of the problem. Oral steroids such as prednisone do the same, but are generally not used for this purpose because of significant side effects. Use of non-steroidal anti-inflammatory drugs may worsen asthma symptoms in some with a history of asthma, making the use of steroids such as prednisone the safer option for treating CTS. The most common complications associated with long-term use of anti-inflammatory medications are gastrointestinal irritation and bleeding. Also, some anti-inflammatory medications have been linked to heart complications. Use of anti-inflammatory medication for chronic, long-term pain should be done with doctor supervision.
A more aggressive pharmaceutical option is an injection of cortisone, to reduce swelling and nerve pressure within the carpal tunnel. Methylcobalamin (vitamin B12) has been helpful in some cases of CTS. 
Release of the transverse carpal ligament is known as "carpal tunnel release" surgery. It is recommended when there is static (constant, not just intermittent) numbness, muscle weakness, or atrophy, and when night-splinting no longer controls intermittent symptoms. In general, milder cases can be controlled for months to years, but severe cases are unrelenting symptomatically and are likely to result in surgical treatment.
In carpal tunnel release surgery, the goal is to divide the transverse carpal ligament in two. This is a wide ligament that runs across the hand, from the scaphoid bone to the hamate bone and pisiform. It forms the roof of the carpal tunnel, and when the surgeon cuts across it (i.e., in a line with the ring finger) it no longer presses down on the nerve inside, relieving the pressure.
There are several carpal tunnel release surgery variations: each surgeon has differences of preference based on their personal beliefs and experience. All techniques have several things in common, involving brief outpatient procedures; palm or wrist incision(s); and cutting of the transverse carpal ligament.
The two major types of surgery are open carpal tunnel release and endoscopic carpal tunnel release. Most surgeons historically have performed the open procedure, widely considered to be the gold standard. However, since the 1990s, a growing number of surgeons now offer endoscopic carpal tunnel release.
Open surgery involves an incision on the palm about an inch or two in length. Through this incision, the skin and subcutaneous tissue is divided, followed by the palmar fascia, and ultimately the transverse carpal ligament.
Endoscopic techniques involve one or two smaller incisions (less than half inch each) through which instrumentation is introduced including a synovial elevator, probes, knives, and an endoscope used to visualize the underside of the transverse carpal ligament. The endoscopic methods do not divide the subcutaneous tissues or the palmar fascia to the same degree as the open method does.
Many studies have been done to determine whether perceived benefits of a limited endoscopic or arthroscopic release are significant. Brown et al. conducted a prospective, randomized, multi-center study and found no significant differences between the two groups with regard to secondary quantitative outcome measurements. However, the open technique resulted in more tenderness of the scar than the endoscopic method. A prospective randomized study done in 2002 by Trumble revealed that good clinical outcomes and patient satisfaction are achieved more quickly with the endoscopic method. Single-portal endoscopic surgery is a safe and effective method of treating carpal tunnel syndrome. There was no significant difference in the rate of complications or the cost of surgery between the two groups. However, the open technique caused greater scar tenderness during the first three months after surgery, and a longer time before the patients could return to work. http://www.ejbjs.org/cgi/content/abstract/84/7/1107
Some surgeons have suggested that in their own hands endoscopic carpal tunnel release has been associated with a higher incidence of median nerve injury, and for this reason it has been abandoned at several centers in the United States. At the 2007 meeting of the American Society for Surgery of the Hand, a former advocate of endoscopic carpal tunnel release, Thomas J. Fischer, MD, retracted his advocacy of the technique, based on his assessment that the benefit of the procedure (slightly faster recovery) did not outweigh the risk of injury to the median nerve. Despite these views, many other surgeons have embraced limited incision methods. It is considered to be the procedure of choice for many of these surgeons with respect to idiopathic carpal tunnel syndrome. Supporting this are the results of some of the previously mentioned series which cite no difference in the rate of complications for either method of surgery. Thus, there has been broad support for either surgical procedure using a variety of devices or incisions. The primary goal of any carpal tunnel release surgery is to divide the transverse carpal ligament and the distal aspect of the volar ante brachial fascia, thereby decompressing the median nerve. http://orthoinfo.aaos.org/topic.cfm?topic=A00005
All of the surgical options (when performed without complication) typically have relatively rapid recovery profiles (weeks to a few months depending on the activity and technique), and all usually leave a cosmetically acceptable scar.
Surgery to correct carpal tunnel syndrome has a high success rate. Up to 90% of patients were able to return to their same jobs after surgery. In general, endoscopic techniques are as effective as traditional open carpal surgeries, though the faster recovery time typically noted in endoscopic procedures is felt by some to possibly be offset by higher complication rates. Success is greatest in patients with the most typical symptoms. The most common cause of failure is incorrect diagnosis, and it should be noted that this surgery will only mitigate carpal tunnel syndrome, and will not relieve symptoms with alternative causes. Recurrence is rare, and apparent recurrence usually results from a misdiagnosis of another problem. Complications can occur, but serious ones are infrequent to rare.
Most people who find relief of their carpal tunnel symptoms with conservative or surgical management find minimal residual or "nerve damage". Long-term chronic carpal tunnel syndrome (typically seen in the elderly) can result in permanent "nerve damage", i.e. irreversible numbness, muscle wasting and weakness.
While outcomes are generally good, certain factors can contribute to poorer results that have little to do with nerves, anatomy, or surgery type. One study showed that mental status parameters, alcohol use, yield much poorer overall results of treatment.
Many mild carpal tunnel syndrome sufferers either change their hand use, pattern, or posture at work or find a conservative, non-surgical treatment that allows them to return to full activity without hand numbness or pain, and without sleep disruption. Some find relief by adjusting their repetitive movements, the frequency with which they do the movements, and the amount of time they rest between periods of performing the movements. Other people end up prioritizing their activities and possibly avoiding certain hand activities so that they can minimize pain and perform the essential tasks. Keyboard re-mapping software can help people whose condition is aggravated by one-handed key strokes involving a combination of the Control, Shift, or Alt keys and an alpha-numeric key. Programs such as Autohotkey allow a person to disable key combinations while they train themselves to use two hands to perform the offending key strokes.
Recurrence of carpal tunnel syndrome after successful surgery is rare. If a person has hand pain after surgery, it is most likely not due to carpal tunnel syndrome. It may be the case that a person who has hand pain after carpal tunnel release was diagnosed incorrectly, such that the carpal tunnel release has had no positive effect upon the patient's symptoms.