Within the past decade, the number of carpal tunnel syndrome (CTS) cases apparently has declined, but that decline may be less a product of improved ergonomics and working smarter than it is the gift of improved diagnostic criteria and techniques. Thus, while CTS is not epidemic, it"s still a hazard for your best employees.
The carpal tunnel is a slender conduit in the base of the palm through which the flexor tendons of the fingers and thumb and the median nerve pass. The tunnel is defined by the carpal bones of the wrist and the transverse carpal ligament. The median nerve, which extends from the fingertips to the neck, delivers power to the thumb muscles and sensation to the thumb, index, middle and part of the ring fingers. When tissues within the carpal tunnel are inflamed or swell, the median nerve is compressed, producing searing pain in the wrist, particularly at night, numbness and tingling in the fingers, and the inability to grasp objects.
Margit L. Bleecker, M.D., director of the Center for Occupational and Environmental Neurology, Baltimore, notes that symptoms similar to CTS can arise if function in the median nerve is impaired or subjected to compression at its origin in the neck. According to Stephen A. Dawkins, M.D., MPH, BS, FACOEM, medical director, Hospital Occupational Medicine, Atlanta, misdiagnoses of CTS were common as recently as five years ago, but patients and doctors have become better educated about CTS, even as diagnostic tools have become more sophisticated.
Making the Diagnosis
Diagnosing CTS begins with taking a medical history of the patient and performing a physical examination. The medical history identifies predisposing factors, such as diabetes, tendinitis, fluid retention, wrist fracture, rheumatoid arthritis, hypothyroidism, tumors, pregnancy and obesity.
"In the physical exam, we look not only at the median nerve, but at the other muscles, tendons and nerves in the upper extremity, beginning at the neck and working down to the fingertips," says Bleecker.
Nerve conduction and electromylegraphic studies are performed to detect abnormalities in the median nerve. X-rays can help rule out arthritis and identify old fractures. The doctor may tap the skin over the median nerve to produce tingling in the fingers Tinel"s Sign or may perform Phalen"s test, in which the patient places his arms with elbows flexed on the table, allowing his wrists to fall forward freely. Tingling in the fingers appears within one minute in patients with CTS. Bleecker also uses video analysis of the patient at work and biofeedback, in which electrodes attached over the patient"s muscles alert him to risky postures.
Despite the precision of these diagnostic tools, "The physical exam is probably one of the weakest [diagnostic tools] we have," Bleecker observes. "That"s why the history so important."
"We try to answer the question of the source. That involves getting the history of when these symptoms occur, what makes them worse or better, and where they are located," she explains. "In an occupational setting, for example, when there is a constant jacking up of workload, people do not have time to adjust. If you increase the speed of an assembly line, you can bring on the symptoms; slow it down and you"ll see the symptoms go away." Bleecker opposes the four-day, 10-hour-per-day work week for the same reason.
Further, says Bleecker, "Gender clearly is an issue. Contrary to old literature, which identifies the ratio of women to men who suffer from CTS at 10 to 1, my experience puts it at 2 to 1. It depends upon the nature of the job."
Dawkins divides risk factors into occupational, medical and hobby categories and asks the patient questions about each. When risk factors are identified, the next step is to discern the percentage of the day spent in those activities and to determine how medical conditions are being controlled.
Armed with this information, he evaluates the severity of the problem, based on the symptoms" frequency, duration and intensity, relative to previous visits. "This teaches them to think about their symptoms in a quantifiable way," he says.
Dawkins notes that misdiagnoses can occur when patients" symptoms mimic those of CTS, but they fall into one of three clinical categories:
1. The nerve conduction test is negative and the symptoms inconclusive,
2. Pressure on the median nerve stems from tendinitis or tenosynovitis. When the inflammation is treated, the CTS-like symptoms disappear, or
3. The patient experiences wrist pain, but other symptoms are inconclusive.
As a result, CTS may be diagnosed even though the symptoms do not necessarily confirm it.
Bleecker advocates educating both workers and managers about the dangers of poor postures and CTS. Early detection, she says, can lead to prevention, retraining the person to use safer postures, or to conservative treatment that manages the problem early in its development.
"I want people to understand that, as soon as they develop symptoms for the first time, they [must] report them to the health center, " she says. "These symptoms occur at home, not at work. The individual does not relate them to work. It is not until he has persistent numbness and the wrist is sore and difficult to move that he brings the problem to someone"s attention.
"Many things in the workplace can be changed easily at no great expense so that you decrease the ergonomic stress that the wrist and hand are exposed to. People also have to realize that they have to get up and take a break -- even with a deadline." Managers can help by identifying and retraining faulty technique: "The employee doesn"t often see himself doing something incorrectly, but a video can show him what should be corrected," says Bleecker. "Technique is important. You can get an ergonomically designed chair and workstation and an employee will still develop CTS because the equipment is not being used properly."
Once a diagnosis is made, the physician may prescribe oral anti-inflammatory medicines and dorsal wrist splints to return the hand to its natural resting posture, relieving pressure in the wrist. Splints are worn at night if people are symptomatic only at night, but those who are symptomatic during the day wear them then, too. Bleecker opposes the practice of wearing splints at work because they limit use of the hand, force it into awkward positions, and can lead to atrophy in some muscles.
Physical therapy is another conservative treatment. Dawkins points out that a program of passive strengthening exercise may be helpful in very early-stage CTS by strengthening the muscles that support the carpal tunnel area; however, he cautions, moderate-to-severe CTS patients "always get worse from exercise." Physical therapy consisting of alternating ice and heat applications can be helpful in controlling inflammation, but exercise therapy isn"t for everyone. The goal of these exercises is to preserve movement and function in the wrist and hand and to prevent atrophy and loss of strength, but Dawkins warns that physical therapy does pose risks and "is best applied with some thoughtful consideration."
Lin Beribak, OTR/L, C.H.T., a therapist at the practice of Drs. Bell, Stromberg, Harris, Nagle & Stogin Ltd. in Chicago, suggests that appropriate physical therapy provides tools for managing daily living. "We look at what aggravates the nerve, including positions which produce a lot of flexion, extension or ulnar deviation, as well as those which cause a shift in the bones of the wrist, compressing the median nerve," Beribak explains. "We look at the whole posture. Is the pressure coming from the wrist alone, or from higher up? For example, people who sleep with a splint may find their fingers still go numb. Sleeping in a fetal position imposes pressure on the median nerve at the wrist. We relieve this by finding a more open sleep posture.
"We also do upper extremity posture balance exercises to break up the forward-roll posture, and scapular and upper and lower trapezius-strengthening exercises to rebalance the body."
Beribak is adamant that a medical diagnosis must precede physical therapy. "The physician must look at the whole person, from the neck down," she says. "A good medical evaluation is critical to good rehabilitation."
"It is important for us to make clear to the patient that this [therapy] is not a one-time deal," Beribak says emphatically. "Even after carpal tunnel surgery, the problem will recur if the patient goes back to abusing the way he uses his body, and it is his responsibility to change the way he uses his body."
Worst-Case Situations
If these measures fail, they may be supplemented by injections of anti-inflammatory agents into the wrist.
Surgery is the last option. Traditional surgery divides the transverse carpal ligament and enlarges the carpal tunnel, thus relieving pressure on the median nerve.
In recent years, endoscopic surgery has become the method of choice because there is less tissue disruption and faster healing. Two tiny incisions are made in the wrist and a slim metal tube containing a scalpel blade is slipped into the tissues between them. The surgeon divides the transverse carpal ligament, the tube is withdrawn, and the incisions closed. Done on an outpatient basis, endoscopic surgery is followed by 24 to 72 hours of post-surgical discomfort, suture removal in about two weeks, gradual resumption of activities for the affected hand, and the return of strength and sensation within a year.
Dawkins observes that how quickly a CTS patient progresses from stages one and two to surgery depends largely upon what doctor the patient sees. "If somebody has a recommendation for surgery, he or she absolutely should get a second opinion," he says.
Some CTS cases are beyond surgical amendment. "If the symptoms have existed for more than one year, there is a greater likelihood of permanent nerve damage," Dr. Dawkins notes. "It would be unrealistic to expect that they would have full resolution of the symptoms with surgery. On a risk-benefit analysis, is it worth it to go through a surgery where your pain may only decrease by 10 or 20 percent?"
Dawkins does not discount the possible value of acupuncture, but comments that no scientific studies support its use and no formal protocol for identifying good candidates for acupuncture is available.
The popular practice of taking vitamin B-1 to ward off CTS is another matter entirely.
"B-1 is a vitamin that sometimes can contribute to the development of CTS in patients who are B-1 deficient, typically during pregnancy or when someone has a metabolic disorder," he explains. "There is marginal value from a person who has a normal eating history and an adequate B-1 level getting B-1 shots or taking supplements." Excessive doses of vitamin B-1 may result in permanent damage to the nerve cells.
Bleecker, Dawkins and Beribak concur on the issue of return-to-work. Should the CTS stem from a nonwork source, returning to the job is of small concern; however, if occupational risk factors are responsible, returning to that same job -- unmodified -- brings with it the likelihood that the person"s condition will worsen.
The consequence of not taking preventive ergonomic measures in the workplace is future risk: Jackson, Tenn.-based IPS Physician Services, a workers" compensation medical management and cost containment company, estimates that an average of 15 percent of all new hires have median nerve compression at the wrist (a precursor to CTS) when they are hired. A workplace where the environment and workflow are geared only toward speed and quotas, rather than good body mechanics and productivity, is one in which medical icebergs -- among them, CTS -- lurk.
Supplementary technical information for this article was provided by The Cleveland Clinic Foundation.