It is important to note that unless numbness is one of 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, is not likely to fall under this diagnosis.

Carpal tunnel syndrome is known as a "hidden disability" because people can do some things with their hands and appear to have normal hand function. However, despite these appearances, those afflicted often live with severely restricted hand activity due to the pain.

Causes

Work and carpal tunnel syndrome

However, recent studies and peer review articles have found no relationship between carpal tunnel syndrome and office-type work. Recently the Harvard Medical School published a report in which it addressed carpal tunnel syndrome. The Harvard report cited to the 2003 Journal of American Medical Association study }} and the 2001 study in Neurology (the Mayo Clinic Study }}) in reporting that computer use did not increase a person's risk of developing carpal tunnel syndrome. Several studies have indicated a strong correlation between an employee's general physical condition and carpal tunnel complaints.

Hyperthyroidism, osteoarthritis and diabetes were most often associated with CTS-like symptoms, as were variables such as age, obesity and wrist dimension. In a studies by SG Atcheson, only 35 of 297 subjects were aware of the underlying health condition which could account for their CTS like symptoms. }}^, }} Hence, these causes would be missed by doctors if they were relying on a patient's health history to rule out other causative factors. It is important that a doctor rule out other causes of CTS-like symptoms. If a patient does not have CTS, corrective surgery is destined to fail.

Studies have also related carpal tunnel and other upper extremity complaints with psychological and social factors. A large amount of psychological distress showed doubled risk of the report pain, while job demands, poor support from colleagues, and work dissatisfaction also showed an increase in the report of pain, even after short term exposure. }}

On the other hand, in 1997, studies done by the National Institute for Occupational Safety and Health (NIOSH), indicated that job tasks involving highly repetitive manual acts or necessitating wrist bending or other stressful wrist postures were connected with incidents of CTS or related problems. However, it appears that the 30+ studies reviewed were concerned with the occupations of assembly line workers, meat packers, food processors, and the like, not general office work.

This panoply of medical and scientific studies are consistent in finding no statistically significant relationship between upper extremity repetitive trauma claims and the workplace.

In summary, carpal tunnel syndrome can easily be aggravated by activity. It occurs frequently in the population. People that develop symptoms will frequently blame this on their work exposure, even though this exposure may indeed have little to do with the root cause of their carpal tunnel syndrome. This is where the mixture of science, economics and social policy combines to determine societal behavior and expectations in individuals.

Trauma-based causes

• Fractures of one of the arm bones, particularly a Colles' fracture.
• Dislocation of one of the carpal bones of the wrist.
• Strong blunt trauma to the wrist or lower forearm, incurred for example by using arm extremity to cushion a fall or protecting oneself from falling heavy objects.
• Hematoma forming inside the wrist, because of internal hemorrhaging.
• Deformities due to abnormal healing of old bone fractures.

Non-traumatic causes

• Tenosynovitis, which is inflammation of the thin mucinous membrane around the tendons. Part of the process of inflammation is swelling, and this compresses the nerve. Swelling of this membrane is the final common pathway for most cases of carpal tunnel, whether caused idiopathically, through exposure, or medically.
• With pregnancy and hypothyroidism, fluid is retained in tissues, which swells the tenosynovium.
• Acromegaly, a disorder of growth hormones, compresses the nerve by the abnormal growth of bones around the hand and wrist.
• Tumours (usually benign), such as a ganglion or a lipoma, can protrude into the carpal tunnel, reducing the amount of space. This is exceedingly rare (less than 1%).
• Diabetes, rheumatoid arthritis, and obesity tend to cause swelling and thickening of the tenosynovium, thus decreasing the amount of space left for the median nerve in the carpal tunnel.
• Double crush syndrome, where there is compression or irritation of nerve branches contributing to the median nerve in the neck or anywhere above the wrist. This then increases the sensitivity of the nerve to compression in the wrist. This, while a possible factor, is also a rare contributor in most cases.
• Idiopathic causes, which no one can explain, can also cause this disease. This is very common.

• Common activities that have been identified as contributing to repetitive stress induced carpal tunnel syndrome include:
  • Computer keyboarding or typing in some situations, especially when keying over 15,000 ksph (Key Strokes Per Hour) is performed. The exact relationship has not been proven, however.
  • Playing video games or computer games
  • Playing a musical instrument
  • Any activity where hand use is vigorous and routine could contribute (surgeons, dentists). Still, these activities are often merely associated with, but do not actually cause, carpal tunnel syndrome.

Often people suffering from carpal tunnel syndrome can have multiple contributing factors which are aggravated by vigorous hand activities and repetitive stress trauma to the hand.

Proper attention to ergonomic considerations can reduce or eliminate these kinds of exposures.

While carpal tunnel syndrome is often called a "repetitive strain injury" (RSI) or "cumulative trauma disorder" (CTD), these labels are looked down on by medical doctors, particularly hand specialists. Carpal tunnel is a specific condition with specific typical symptoms that responds fairly reliably. Most of the time carpal tunnel is not caused by an "strain" or "trauma" of any type. RSI and CTD are relatively non-specific terms with non-specific symptoms that respond variably to treatment. Labelling someone with RSI or CTD can be unhealthy psychologically.

Diagnosis

Phalen's maneuver is performed by flexing the wrist gently as far as possible, then holding this position and awaiting symptoms. A positive test is one that results in numbness in the median nerve distribution. The quicker the numbness starts, the more advanced the condition.

A classic, though less effective method, Tinel's sign, is a way to detect irritated nerves. It is performed by lightly tapping (percussing) over the nerve to elicit a sensation of tingling or "pins and needles" in the distribution of the nerve. Tinel's sign is sometimes referred to as "distal tingling on percussion" or DTP. Carpal compression test, or applying firm pressure in the palm over the nerve to elicit symptoms has been discussed as a valuable test. }}

If, based on history and physical examination, carpal tunnel is suspected, then patients will likely be tested electrodiagnostically with nerve conduction studies or electromyography. These are objective measurements that look at the health of the nerve and can be correlated to the symptoms.

Treatment and Prevention

Immobilizing braces

Physiotherapy treatments

Localized Steroid Injections

Prioritizing Hand Activities and Ergonomics

More frequent rest can be useful if it can be orchestrated into one's schedule, but rest is not very practical in today's active work and play environments. 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, which is a 30 sec. pause every 3 to 5 minutes (the more severe the pain, the more often one should take this break). 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 reducing the stress on the wrists which will alleviate wrist pain and strain involve adopting a more ergonomic work and life environment such as using an ergonomic keyboard (and perhaps switching from a QWERTY key layout to a more efficient Dvorak Simplified Keyboard layout). Studies have shown ergonomic keyboards reduce wrist stress by 30% or more and Dvorak reduces stress an additional 30%. It's also important that ones 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. Spinal manipulations performed by an osteopath or chiropractor may be appropriate to relieve compression of the nerve.

Dietary Changes and Medication

Using an over-the-counter anti-inflammatory such as aspirin or ibuprofen or Naproxen can be effective as well for controlling symptoms. Pain relievers like Tylenol will only mask the pain, and only an anti-inflammatory will affect inflammation. Non steroidal inflammatory medications theoretically can treat the root swelling and thus the source of the problem. Oral steroids (prednisone) does the same but is generally not used for this purpose due to significant side effects. The most common complications associated with long-term use of anti-inflammatory medications are gastrointestinal irritation and bleeding. Also, some anti-inflammatory medication have been linked to heart complications. No one should rely on these type of medications for chronic long-term pain without a doctor's supervision.

A more aggressive pharmaceutical option is an injection of cortisone, to reduce swelling and nerve pressure within the carpal tunnel.

Carpal Tunnel Release Surgery

If all the symptoms go away with splinting and medication, then surgery will not be necessary. If not, then the "carpal tunnel release" surgery is recommended. }} In general, milder cases can be controlled for months to years, but severe cases are unrelenting symptomatically and likely will come to surgical treatment. }}

There are several variations of technique to perform carpal tunnel release surgery. Each surgeon has differences of preference based on their personal beliefs and experience. All techniques have several things in common.

• They all involve brief (10-15 minute) outpatient procedures.
• They all involve some type of incision(s) on your wrist and/or palm.
• They all involve dividing (cutting) the transverse carpal ligament.
• They all incur a relatively rapid recovery time (days to weeks depending on the activity and technique).
• They all leave a cosmetically insignificant scar in most cases.

The two major types of surgery are open and endoscopic. Most surgeons perform open surgery, which is widely considered to be the gold standard. However, many surgeons are now performing endoscopic techniques. Open surgery involves a small incision somewhere on the palm about an inch or two in length. Through this the ligament can be directly viewed and divided with relative safety. Endoscopic techniques involve one or two smaller incisions (less than half inch each) through which instrumentation is introduced including probes, knives and the scope to see what you are doing. The ligament is viewed through a "keyhole" in this way and can be divided with relative safety. There are perhaps a half dozen commercial systems available that surgeons can use to do the endoscopic surgery.

Much debate has existed in the medical community of which technique is best. Open surgery is arguably a bit safer as there is less likelihood of inadvertent damage to surrounding nerves and blood vessels. Endoscopic surgery very likely will result in a quicker early recovery. In other words, people will feel less sore and be able to be more active in the several (1-5) weeks after surgery with endoscopic techniques. Several studies have suggested that either technique leaves patients with similar results if examined after about six weeks.

If the decision to operate is made, the technique choice is between the patient and surgeon. Surgeons can do either or both techniques. Surgeon can tailor treatments to patients' specific needs.Surgery to correct carpal tunnel syndrome has given a 90% or better success rate, especially using endoscopic surgery techniques. }}^, }}^, }} In general, endoscopic techniques are as effective as traditional open carpal surgeries }}^, }}, though the faster recovery time typically noted in endoscopic procedures may be offset by higher complication rates. }}^, }} Success is greatest in patient with the most typical symptoms. The most common cause of failure is incorrect diagnosis, and it should be noted that this surgery will only fix carpal tunnel syndrome, and will not relieve symptoms with alternate 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.

Carpal tunnel surgery is usually performed by an orthopaedic or plastic surgeon; some neurosurgeons and general surgeons also perform the procedure.

Long term recovery

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. symtoms of 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, and involvement of an attorney yield much poorer overall results of treatment. }} This really demonstrates how ones mental state, attitude and outlook affect carpal tunnel syndrome and almost any other medical problem that has potential subjective components such as pain and disability status.

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/pain and sleep disruption. Other people end up prioritizing their activities and possibly avoiding certain hand activities so that they can minimize pain and perform the essential tasks.

Changing jobs is also commonly done to avoid continued repetitive stress tasks. Others find success 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.

In summary, one has the choice of controlling the symptoms with any of the non-surgical options listed, or correcting the condition with surgery. }}

While recurrence after surgery is a possibility, true recurrences are uncommon to rare. }} Non-CTS hand pain is commonly mistaken for recurrence. Such hand pain may have existed prior to the surgery, which is one reason it is very important to get a proper diagnosis.

See also

• Ergonomics
• Peripheral neuropathy

References