Carpal Tunnel Syndrome

Description

Alternative Names

Surgery

Every year over 200,000 people in the US undergo surgeries for carpal tunnel syndrome, rendering them among the most common surgical procedures performed on the hand. In various trials, 70% to 90% of patients who underwent surgery were free of nighttime pain afterward.

Candidates for Surgery

Although evidence strongly suggests that surgery is more effective than conservative approaches (at least in patients with moderate to severe CTS), the decision about whether and when to have surgery to correct CTS is a troubling one for patients. Electrodiagnostic and other tests used to confirm the presence of CTS are not very useful in determining the best candidates for surgery. For example, results suggesting severe CTS may not relate at all to surgical success or the lack of it.

In general, patients with the following findings are less likely to respond to conservative therapy and, therefore, might benefit from surgery:

• Older than 50 years.
• Symptoms lasting 10 months or longer.
• Continual numbness.
• The muscles in the base of the palm have begun to atrophy (shrink)
• Symptoms occur within 30 seconds during a Phalen's test.

According to a 2002 study, if none of these factors are present, conservative therapies (splinting and anti-inflammatory agents) are effective in two thirds of patients. However, the conservative approach was ineffective in 60% of patients if only one of these factors were present, in 83% with only two of them, and in virtually all patients who had three or more.

Surgery does not cure all patients, and because it permanently cuts the carpal ligament, some wrist strength is often lost. A number of experts believe that release surgery is performed too often. They recommend aggressive conservative treatment (e.g., splints, anti-inflammatory agents, and physical therapy) before choosing the more invasive option.

Nevertheless, other experts argue that CTS is often progressive and will worsen over time without surgery. Furthermore, evidence now strongly demonstrates that surgery is superior to splints and conservative measures for the relief of pain.

Factors that may increase the chances for favorable surgical results:

• Having surgery performed within three years of the diagnosis of the disorder.
• Being in good general health.
• Having significantly slow nerve conduction results, but also having some preoperative muscle strength.
• Symptoms being worse at night than during the day.

Factors that may reduce the chances for success:

• Being elderly.
• Having very severe preoperative symptoms.
• Being involved with very heavy manual labor, particularly working with vibrating tools. (In some studies, only slightly more than half the people who used vibrating hand-held tools were symptom-free three years after their operations.
• Having very poor nerve conduction results before surgery. (It should be noted that some patients with severe symptoms but who have normal neurologic and physical test results can still experience significant relief from CTS surgeries.)
• Being on hemodialysis. (Such patients have good initial success but about half deteriorate in about a year and a half.)
• Alcohol abuse.
• Having poor mental health.

Factors that make no difference in results:

• Patients whose CTS is due to nerve damage from medical conditions, such as diabetes, rheumatoid arthritis, or hypothyroidism. Such patients appear to have the same outcome as those without such conditions and so such disorders should not preclude them from surgery.

Standard Release Surgical Procedures

Open Release Surgery. Traditionally, surgery for CTS entails an open surgical procedure performed in an outpatient facility. The surgery is straightforward:

• A local anesthetic is injected either into the wrist and hand or higher up the arm. This injection can be very painful for some people. Applying an anesthetic cream before the injection can reduce the pain.
• The surgeon makes a two-inch incision in the palm. In some cases, the incision must be extended into the forearm.
• The surgeon makes further incisions in the muscles of the hand until the carpal ligament is visible.
• The carpal ligament is then cut free from the underlying median nerve. The ligament is literally released and, therefore, the pressure on the median nerve is relieved. Sometimes the lining of nearby tendons is also pared (called flexor tenosynovectomy), but one study showed no benefits from this additional step.

Endoscopy. Endoscopy for carpal tunnel syndrome is a less invasive procedure than standard open release.

Briefly, the procedure is as follows:

• One or two 1/2-inch incisions are made in the wrist and palm, and one or two endoscopes (pencil-thin tubes) are inserted.
• A tiny camera and a knife are inserted through the lighted tubes.
• While observing the underside of the carpal ligament on a screen, the surgeon cuts the ligament to free the compressed median nerve.

Patients report less pain and return to normal activities earlier (about half the time) than those who had the open release procedure. Nevertheless, at this time the best evidence available does not show any significant long-term advantages of endoscopy over open release in terms of muscle or grip strength or dexterity. The endoscopic approach may even carry a slightly higher risk of pain afterward. This may be due to a more limited view of the hand with endoscopy. (In the open release procedure, the surgeon has a full view of the structures in the hand.)

The Mini-Open Approach. In recent years, more surgeons have adopted a mini open--also called short-incision--procedure. It uses only a one-inch incision, but it still allows a direct view of the area (unlike endoscopy, which is viewed on a monitor). The mini-open approach may allow for quicker recovery while avoiding some of the complications of endoscopy, although few well-connected studies have been conducted on its benefits and risks.

In treating carpal tunnel syndrome, surgery may be required to release the compressed median nerve. The open release procedure involves simply cutting the transverse carpal ligament.

Postsurgery Recovery

Timing for Recovery. Patients should expect the following course:

For some patients, release surgery relieves CTS symptoms of numbness and tingling immediately.

• People who have the operation on both hands are completely incapacitated for about two weeks and must have someone to help them at home.
• Returning to strenuous work right after surgery may cause the symptoms to recur. Patients generally stay out of work for at least a month and often much longer, depending upon the type of surgery and severity of the condition. (Recovery time appears to be faster with endoscopy than with open release.)
• Immediately after surgery, however, patients usually experience a decline in grip strength and dexterity. Studies have reported a wide range of recovery in this area. In one, grip and pinch strengths exceeded preoperative status within six weeks. In another, however, grip strength and dexterity did not return to pre-operative levels until 25 weeks after open surgery, and the scar may remain tender for up to a year.
• Peak improvement may take a long time; in one study it took an average of almost ten months.

Physical Therapy. Physical therapy is very important to help rebuild wrist strength. While physical therapy does not reduce the recurrence of symptoms or improve the long-term benefits of surgery, it does accelerate postsurgical recovery. Hand exercises can help restore circulation, muscle strength, and joint flexibility in the hand and wrist. (Wearing a splint to immobilize the wrist after surgery confers no benefits.)

Complications and Long-Term Outcome

In spite of the success of carpal tunnel surgery, treatment failure and complication rates range in studies from 3% to 19%. Postsurgery complications may include the following:

• Nerve damage with tingling and numbness (usually temporary, but some people will always experience residual numbness in the fingertips).
• Infection.
• Scarring.
• Pain (the incision site may remain sore for months, and some patients experience some scar pain for years with open release).
• Stiffness.
• Loss of some wrist strength. Between 10% and a third of patients lose some wrist strength. (Endoscopy may have better results than open release.) Some patients who have jobs requiring high amounts of force to the hand and wrist, then, may not be able to perform them after surgery. Such workers may also have problems in other parts of the upper body, including elbows and shoulders, which are not resolved with surgery and can persist. Studies indicate the between 10% and 15% of patients change jobs after the operation.

If pain and symptoms recur, the release procedure may be repeated. Reasons for failure include:

• Incomplete release of the ligament.
• Extensive scarring.
• Recurrence of the disorder due to underlying medical disorders.

Procedures for Surgical Failure or Recurring Symptoms

Neurolysis. In some severe cases or when scarring is extensive after surgery, surgeons may choose to sever the nerves that are responsible for the pain using a procedure called external or internal neurolysis. The procedure may extend recovery time substantially, and the need for repeat surgeries may be higher in those who undergo the procedure. One report indicated that neurolysis should be considered if there has not been any recovery three months after surgery, after which improvement is unlikely. Nevertheless, it is unclear if this approach offers any benefits beyond conservative measures to free the nerve from surrounding scar tissue.

Implants. In another procedure for recurrent carpal tunnel syndrome, physicians may take muscle flaps or even fatty tissue from other parts of the body and implant them at the site of the nerve injury. Such flaps enhance the development of new blood vessels, provide padding, and possibly serve as a bed for nerve regrowth. These implants may be used with or without nerve dissection. Another procedure called vein wrapping uses grafts taken from veins to help protect the scarred nerves.