Tracy Bobbitt was in her mid-20s when she began to feel numbness and extreme pain in her wrists and hands. The symptoms were so bad they'd wake her up at night and persist throughout the day, often becoming intolerable. Her mother had experienced similar symptoms before she was diagnosed with carpal tunnel syndrome (CTS) in both wrists in her 40s, so Bobbitt wondered if she, too, had the condition.

Carpal tunnel syndrome is a collection of symptoms rather than a distinct disease with a single mechanism or course. Symptoms occur when the median nerve, which runs from the forearm into the palm of the hand, is compressed as it passes through the carpal tunnel, a narrow passage in the wrist. "The tunnel houses nine tendons and a nerve, and if anything causes swelling of the tendons or soft tissue, be it age or activity or some medical disorder, it puts pressure on the nerve," explains Alexander D. Mih, MD, an associate professor in orthopedic surgery at the Indiana University School of Medicine. Symptoms, such as pain in the wrist that may radiate through the forearm, numbness, tingling, or weakness in the hand, usually come on gradually.

Bobbitt's family doctor referred her to an orthopedic surgeon, who suspected CTS based on her history and a physical exam and sent her to a neurologist. The neurologist administered a nerve conduction study, a standard tool used in evaluating CTS. During the test, a very small electrical stimulus is applied to the median nerve, then is recorded at another point once it crosses the wrist. The speed and strength of this electrical signal can indicate whether there is damage to the nerve and, if so, how severe.

Neurologists may also perform an electromyography (EMG) test, which involves inserting a very small needle into the muscles of the arm and hand to record electrical activity. Both the nerve conduction study and the EMG help rule out other conditions and ensure that no other nerve is to blame—an important consideration that affects treatment. In Bobbitt's case, the median nerve speed was slow and the nerve damage was determined to be moderate.

The diagnosis puzzled Bobbitt, who couldn't think of much in her life or her mother's that involved repetitive hand movements, which she thought was associated with the condition.

Identifying Risk Factors

"People come in all the time and say, 'How did I get this? I don't type or do repetitive activities,'" says Russell Gelfman, MD, an assistant professor of physical medicine and rehabilitation at the Mayo Clinic in Rochester, MN, and a renowned expert in CTS who has conducted longitudinal studies following the diagnosis, treatment, and outcomes for thousands of patients over decades. "We know a lot about carpal tunnel syndrome, but we don't know [exactly] what causes it." But risk factors other than simple repetitive hand movements have been identified, including obesity, anatomy, and nerve damage that occurs as a complication of diabetes (neuropathy), says John C. Kincaid, MD, FAAN, a professor of neurology at Indiana University School of Medicine, who treats carpal tunnel syndrome.

Women develop CTS at twice the rate of men, leading some experts to suspect estrogen is involved. "The studies on hormones have been mixed as to whether estrogen itself contributes, but we do know that women tend to have smaller wrists than men, so that could certainly be a factor," says Dr. Gelfman. Women's anatomy, in combination with other factors such as trauma, could increase pressure on the median nerve and, in turn, lead to the syndrome.

Some women may even develop CTS late in pregnancy, when they tend to retain fluid and become puffy. The pressure caused by fluid buildup in the wrist may compress the median nerve, triggering CTS symptoms. Doctors rarely treat CTS in pregnancy because it normally disappears within weeks or months of delivery as the body reabsorbs the excess fluids. An underactive thyroid (hypothyroidism) can also cause CTS for much the same reason: Fluids can accumulate in various body parts, including the carpal tunnel, where they can increase pressure on the nerve. Once the thyroid is controlled, the syndrome goes away on its own.

CTS is not considered an inherited condition because it is not passed down directly from one generation to another. However, because some risk factors such as diabetes, obesity, rheumatoid arthritis, and small wrists can have genetic components, CTS can appear to run in families, as it does in Bobbitt's. In addition to her mother, Bobbitt's aunt and daughter have had CTS too.

Splints for the Syndrome

Doctors often treat CTS first with splinting, says Dr. Mih. "Most people have symptoms at night or upon awakening that seem to come from having their wrist flexed during a portion of their sleep. This increases the pressure, which causes the numbness, tingling, and pain that awakens people from sleep. Splints can help keep the wrist from flexing, which allows the nerve to rest at night, and people don't wake up feeling numb. It also seems to have some protective effect during the day."

Steroids As a Stop-Gap

Bobbitt opted to wear splints on both wrists at night. When that proved insufficient, her doctor administered a steroid injection. "Steroids can remove some buildup of fluid or swelling in the soft tissues and relieve symptoms permanently or for several months," says Dr. Kincaid. It's important to find a hand surgeon or a neurosurgeon with enough skill and experience to inject the steroid into the soft tissue around the nerve but not into the nerve itself, which can damage the nerve and worsen the condition, he adds.

Strong evidence suggests that local steroid injections can provide relief in the short term, and when splinting is unsuccessful, it's initially a reasonable option for someone with CTS. However, repeated use of steroids may be counterproductive in the long run, says Dr. Kincaid. "It appears that steroids delay rather than eliminate the need for more definitive treatment."

When Surgery Is Appropriate 

If splints and steroid injections don't work, surgery may be an option, says Dr. Mih, who regularly performs carpal tunnel release surgery. Surgery expands the tunnel and creates more room for the nerve and tendon, he says. If the operation, which has relatively few complications, is done before the nerve has incurred any permanent damage, it's successful more than 90 percent of the time. If the nerve is permanently damaged or the patient has other underlying conditions such as diabetes, the success rate is about 75 percent. After surgery, some people lose some strength in their hands, but the loss is usually not significant and most people recover fully.

Splints and steroid injections helped Bobbitt manage her symptoms until her mid-30s. When the pain returned and her orthopedist told her the damage to her nerve was progressing, she chose surgery. Both wrists were operated on two weeks apart and required only local anesthesia in the wrist and palm. "I recovered almost immediately, and within hours I felt fine," says Bobbitt. "To this day I've not had a recurrence."

Work to Avoid Carpal Tunnel Syndrome

Although studies show no direct causal link between occupations involving repetitive actions and carpal tunnel syndrome, Dr. Kincaid says the association "is generally known and widely acknowledged." So, for example, if symptoms are exacerbated by typing or using a mouse, doctors recommend learning how to type or grip a mouse less forcefully.

For other workplace fixes, employers may turn to an occupational therapist and certified hand therapist. Donine Schaffer, for example, is often called into offices to assess which tasks cause the most incidence of carpal tunnel syndrome. "I put in ergonomic keyboards, keyboard trays, and adjustable chairs. With these in place, [employees] can get into good ergonomic position from day one, and the incidence of carpal tunnel goes down," she says.

She also customizes work spaces for people who have been diagnosed with the syndrome. She recommends that "when sitting at a computer station, the wrist should be in a neutral position, with a little extension, elbows at 90 degrees, and shoulders relaxed." In her experience, catching bad habits early can "eradicate the problem."

However, not all occupations and workplaces can be adapted so easily. "Some of the newest data show that activity that requires a lot of forceful gripping can make the syndrome worse," says Dr. Gelfman. For example, jobs involving vibrating handheld tools like sanders have been associated with carpal tunnel syndrome. Not everyone required to do such activities will develop CTS, but their risk may be higher, he says.

Reduce Your Risk

Over the years, researchers have developed a more nuanced perspective on carpal tunnel syndrome, acknowledging that it's caused by more than just repetitive action. Some people have an anatomical predisposition, which could explain why one person develops CTS while another doesn't, even if they're both engaged in similar repetitive activities. "People with diabetes have an increased tendency to get CTS, perhaps because the underlying neuropathy makes the carpal tunnel more susceptible to normal compression," says Dr. Kincaid.

Fortunately, most risk factors for CTS are within people's control. Experts suggest making your workspace more ergonomic, keeping your weight in check, gripping less forcefully, and, if you're at risk for type 2 diabetes, seeing a doctor.

Is It Carpal Tunnel Syndrome?

Carpal tunnel syndrome (CTS) usually comes on gradually and progresses slowly, says John C. Kincaid, MD, FAAN, a professor of neurology at Indiana University School of Medicine, who treats CTS. Early symptoms include a tingly sensation in the index, middle, and ring fingers, and sometimes the thumb, he says. People may also experience numbness, which can appear suddenly—for example, when you're driving a car with your hand on the steering wheel.

If you shake your hand and the sensation returns reasonably quickly, you may have only mild CTS. "If those tingly sensations increase in duration for minutes or hours at a time, or they wake you up every night or maybe multiple times per night, it's time to seek medical care," says Dr. Kincaid.

It's important to get help before damage to the median nerve becomes permanent, says Dr. Kincaid. But because CTS develops slowly, most people will have time to treat their condition before that happens.