Overview

Carpal tunnel syndrome, or CTS, is a condition in the wrist caused by the compression of the median nerve. This compression can make parts of the hand numb, tingle, or have occasional pain. CTS is a very common problem. More and more cases are from trauma caused by repetitious movements, especially computer use. While CTS can often be successfully treated non-operatively, surgery may be necessary in some cases.

What is the carpal tunnel?

The carpal tunnel is a narrow channel on the palm side of the wrist. Eight bones, called carpals, form an arch creating three rigid walls of the channel. A tight, broad band of tissue, called the transverse carpal ligament, covers the arch and forms a roof over the channel. This "tunnel" is the protective passage for the median nerve and all nine tendons that bend the fingers and thumb. A nerve has two functions:

  • to relay information about sensations (like touch, temperature, and pain).
  • to control muscles.

The median nerve relays sensations from the thumb, the index finger, the long finger, and the thumb side of the ring finger. This nerve also controls several small muscles in the hand, especially muscles that move the thumb.

What is carpal tunnel syndrome?

Carpal tunnel syndrome, or CTS, is caused by pressure or pinching of the median nerve as it passes through the carpal tunnel on its way to the palm of the hand. For example, there are conditions that can irritate the covering (sheath) of the tendons and can cause this sheath (which also passes through the tunnel) to swell. The tunnel is a rigid, confined space, so any inflammation or swelling in the tunnel can compress the median nerve. This leads to weak and poorly functioning hand muscles. Symptoms may include numbness, tingling, and occasionally pain.

CTS is most often related to work activities that involve repetitive motions, In addition to computer use, the repetitive motions of assembly line workers, cashiers, and hairstylists put them at risk for CTS. Other common causes of CTS are:

  • infections or growths within the tunnel that take up space and compress the median nerve.
  • osteoarthritis, or other problems with the carpals (wrist bones).
  • diseases which cause inflammation or fluid build-up like rheumatoid arthritis, diabetes, and hypothyroidism.
  • pregnancy: hormonal changes may cause fluid retention, which can increase pressure on the median nerve. This condition usually improves after pregnancy.

Some people may be born with a condition that puts them at risk to develop CTS. For example, a carpal tunnel that is smaller than average leaves little room for the nerve and tendons. Anything causing swelling around the nerve can increase the pressure on it. The median nerve can only tolerate a small amount of pressure for a short time. Increased pressure over time can cause the hand to "fall asleep". The longer the condition exists, the worse the symptoms become.

What are the signs and symptoms of carpal tunnel syndrome?

Numbness - The first symptom is usually numbness or tingling in the thumb, index finger, long finger, and ring finger. Everyday activities that bend (flex) the wrist can make the numbness worse. Some examples of everyday activities that can cause problems are driving, writing, holding a book or newspaper, combing hair, or sleeping in an awkward position. Initially, the numbness may come and go. As the condition worsens, the numbness becomes more constant.

Weakness/ Muscle Loss - Patients may notice their grip weakening as the pressure on the median nerve increases. Over time, the muscles of the thumb will become smaller (atrophy).

Dropping Objects - Because of a weakened grip, patients frequently complain about dropping objects. This weakening, plus the loss of feeling in the thumb and fingers, does not allow the patient to notice the object slipping from the hand.

Pain - Pain is a less common symptom. The constant numbness can feel painful. A persistent ache, particularly in the thumb, may spread up to the shoulder, the neck, or both. In severe cases, there may be a constant burning pain in the wrist and hand.

How is carpal tunnel syndrome diagnosed?

History -The doctor often suspects CTS from the patient's history and symptoms. If the patient complains of numbness and tingling in the thumb and fingers (supplied by the median nerve) the doctor suspects CTS. If symptoms worsen with the typically suspected activities (such as driving, writing, reading, or combing hair) or the patient's work and activity patterns involve repetitive motions, the doctor will suspect CTS.

Examination - The doctor will determine if there is decreased feeling in the thumb, index finger, long finger, and ring finger. In severe cases, the doctor may find that the muscles of the thumb have atrophied (become smaller).

Testing - The doctor may do some manual tests to confirm the diagnosis of CTS.

  • Phalen's Maneuver - The patient holds the wrist in a bent position for one minute. If CTS is present, the added pressure on the nerve will make the numbness worse.
  • Tinel's Sign - The doctor will gently tap on the wrist where the median nerve travels through the tunnel. Patients with CTS experience a feeling of electricity or tingling, similar to the sensation that occurs when the "funny bone" is bumped.
  • Electrodiagnostic Studies - Physicians who specialize in nerve function often use more objective techniques to confirm CTS and evaluate the severity of nerve damage. These tests are not essential to make a diagnosis of carpal tunnel syndrome, but they are very helpful in ruling out other problems like pinched nerves in the neck or arm.
  • A nerve conduction study is performed by applying a very mild electrical current along the path of the nerve. The speed the current travels along the nerve indicates how well the nerve is working.
  • Electromyography measures the electrical activity of muscles. Extremely small, threadlike needles are placed in certain muscles. Any deviation from normal muscle activity indicates a problem with the nerve supply to that muscle.

This first level of treatment is the most conservative.

  • A wrist splint is used to hold the wrist in a straight position. The splint is usually worn during sleep. When sleeping, it is natural to curl up with the wrists bent. This position places pressure on the median nerve causing the symptoms of numbness and tingling to flare up. The use of a splint often reduces these symptoms. Many patients like to wear the splint during the day, as well. Extreme positions that put pressure on the nerve should be avoided.
  • Oral anti-inflammatory medication, such as ibuprofen, may help reduce the swelling around the tendons. Once the swelling is reduced and pressure is taken off the median nerve, symptoms usually lessen. The most common side effect from ibuprofen is an upset stomach. Taking the medication with food reduces that possibility.
  • Activities that cause irritation of the area should be avoided. There are many activities associated with carpal tunnel syndrome. Whether these activities cause CTS is still unknown. Nevertheless, repetitive tasks that make symptoms worse should be avoided. Computers, ten key, cash registers, assembly lines, and meat cutting are just some of the suspected activities. Computer use is commonly blamed for aggravating CTS. It is important that the workstation be arranged to avoid awkward postures. Patients should take frequent breaks from the computer (at least 5 minutes every half-hour) and, as much as possible, avoid long hours at the computer. During these breaks, stretching exercises can be helpful. Less than half of CTS patients (about 20% to 50%) become symptom-free with the most conservative treatment. A steroid injection to reduce inflammation is typically the next step if symptoms are not controlled by the above treatments. The doctor injects the medicine into the tunnel using a very small needle.

The success rate for patients receiving injections is again relatively low, as only 20% to 50% of patients get relief from an injection. The condition may improve temporarily, but symptoms often return. Injections are more successful in patients over 60 - 70 years of age than in the younger population. Patients who experience some improvement with the injection tend to benefit from surgery, as the improvement indicates that swelling and pressure were the causes of the problem. If there is no noticeable improvement after the injection, other conditions causing the symptoms should be considered.

What types of complications may occur?

Complications from non-operative treatment are few and rare. Taking anti-inflammatory medication may cause the patient to experience an upset stomach, or possibly develop an ulcer. The only significant risks are associated with the steroid injection, and these are small. These risks include infection, weakening of the tendons, and possible damage to the nerves or blood vessels. The most common problem of conservative treatment is the failure to relieve the symptoms. As earlier mentioned, only about half, or less, of CTS patients have success with the non-operative treatment method.

Surgery may be indicated if the:

  • the patient's symptoms have not responded to nonoperative treatment.
  • the symptoms are very severe, or nerve testing indicates significant damage to the median nerve.
  • the patient has had symptoms for a number of years before seeking medical advice. It may be better to proceed directly to surgery in these types of cases.

The operation is a short procedure usually done in an outpatient setting. The 30-minute procedure can be performed with a local or regional anesthetic allowing the patient to remain awake during the operation.

The two most popular procedures are the open technique and the endoscopic technique.

  • Open Technique- Also called an "open release". In this procedure a small incision is made at the base of the palm. This allows the surgeon to see and cut the transverse carpal ligament to open the roof of the tunnel. By releasing the ligament, pressure on the median nerve is eliminated.
     
  • Endoscopic Technique - This procedure uses a small tube that the doctor inserts through a ½" incision in the patient's palm or wrist. A fiberoptic camera in the tube allows the surgeon to see the underside of the transverse carpal ligament, which can then be released with a special knife.

Both of these techniques have relatively high success rates; approximately 90% of patients get relief from their symptoms. There are advantages and risks associated with each method. The preferred procedure depends on the surgeon's experience and should only be selected after the options have been discussed in detail.

What types of complications may occur?

There are possible complications from surgical treatment, but they are relatively rare. There are risks associated with anesthesia, infection, and possible injury to nerves, vessels, or tendons. Other potential problems following surgery include finger stiffness, a tender scar, persistent numbness, and (rarely) increased pain.

Nonoperative Treatment

With non-operative treatment, symptoms can subside in a few days, but more commonly, relief may take as long as several weeks or months. Treatment continues as long as the symptoms seem to improve and they do not interfere with daily activities.

To control symptoms, it may be necessary to make changes in everyday activities (both work and play). The patient should:

  • decrease repetitive motions.
  • keep the wrist straight.
  • use a proper grip (use as much of the hand and as many fingers as possible).
  • rest periodically and alternate hands.
  • use less pressure and slow movements.

Operative Treatment

  • After surgery, the hand will be bandaged, often in a splint, and kept elevated. To reduce swelling, the hand must be kept above the elbow, and the elbow above the shoulder. Most doctors suggest early finger motion to prevent stiffness.
  • The incision must be kept dry until the bandage and stitches are removed at the follow-up appointment. Typically, this appointment occurs about 7 to 14 days after surgery.
  • Patients often notice improvement in symptoms within days after the surgery and some get immediate relief. In more severe cases, the improvement may occur gradually over several weeks or months.
  • Hand therapists may prescribe exercises to help improve circulation, motion, and muscle strength. Post-operative therapy is not always necessary. The doctor should be consulted if stiffness, scar tenderness, persistent pain, or weakness develops after surgery.

1. Phalen, George S. The Carpal Tunnel Syndrome. Seventeen years experience in diagnosis and treatment of six hundred fifty-four hands. JBJS 48-A, 211, 1966.

2. Szabo, Robert M. and Steinberg, David R.: Nerve entrapment syndromes in the wrist. J. Am. Acad. Orthop. Surg., 2:115-123, 1994.

3. Brown, Richard A. et al, Carpal Tunnel Release, JBJS, 75-A, 9, 1265-1275, 1993.

4. Plancher, Kevin D. et al, Carpal and cubital tunnel surgery, Hand Clinics, 12:2, 1996.

5. De Stefano, F. et al, Long term symptom outcomes of carpal tunnel syndrome and its treatment. J. Hand Surg, 22A, 200-210, 1997.

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