Surgery

Every year more than 200,000 people in the US undergo surgeries for carpal tunnel syndrome. Surgery for CTS is among the most common hand surgeries. In various trials, 70 - 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 to have surgery to correct CTS, and when to have it, 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 characteristics are less likely to respond to conservative treatment and, therefore, might benefit from surgery:

• Older than 50 years of age
• Symptoms lasting 10 months or longer
• Continual numbness
• Muscles in the base of the palm have begun to 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 (such as splints, anti-inflammatory agents, and physical therapy) before choosing the more invasive option (surgery). Nevertheless, other experts argue that CTS is often progressive and will worsen over time without surgery. Furthermore, evidence now shows that surgery is better than splints and conservative measures for the relief of pain. Factors that may increase the chances for successful surgery:

• Having surgery performed within 3 years of the diagnosis of the disorder
• Being in good general health
• Having very slow nerve conduction results, but also having some muscle strength before surgery
• Symptoms are worse at night than during the day

Factors that may reduce the chances for success:

• Being elderly may affect the chances of successful surgery. However, a study found that the majority of patients over age 65 who had surgery were either completely or very satisfied.
• Having very severe symptoms before surgery may reduce the chance for successful surgery.
• Performing heavy manual labor, particularly working with vibrating tools, may lead to a less successful surgery. Medical evidence has found that only slightly more than half the people who used vibrating hand-held tools were symptom-free 3 years after a CTS operation.
• Having very poor nerve conduction results before surgery may reduce the chance for successful surgery. However, some patients with severe symptoms who have normal neurological and physical test results, could still experience significant relief from CTS surgeries.
• Patients who are on hemodialysis have good initial success, but approximately half deteriorate in about a year and a half.
• Alcohol abuse can negatively affect the results of CTS surgery.
• Poor mental health can lead to less successful surgery.
• Patients with diabetes and high blood pressure may be more likely to require a second operation.

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 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. In this procedure, the carpal ligament is cut free (released) from the median nerve. The pressure on the median nerve is therefore relieved. The surgery is straightforward.

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.

The Mini-Open Approach. In recent years, more surgeons have adopted a "mini" open -- also called short-incision -- procedure. This surgery requires 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 studies have investigated its benefits and risks. In a 2005 report, the mini-open approach was directly compared with open release surgery. The recovery time in patients receiving the mini-open approach was shorter than with the open approach,  and results were about the same 30 months after the surgery.

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

• A surgeon makes one or two 1/2-inch incisions in the wrist and palm, and inserts one or two endoscopes (pencil-thin tubes).
• The surgeon then inserts a tiny camera and a knife 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 than those who had the open release procedure, and return to normal activities in about half the time. 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.) One report indicated a nearly 3-fold increased risk of reversible nerve injury with endoscopic carpal tunnel release, compared with open carpal tunnel release. On the other hand, a recently published review of 486 patients, who had a total of 753 endoscopic release procedures, showed an extremely low number of complications following the procedure. This study calls into the question the widely held belief that endoscopy carries a higher risk of complications. The study also noted that 90% of the patients returned to their original line of work.

Recovery After Surgery

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 return. 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 patients usually experience a decline in grip strength and dexterity. Studies have reported a wide range of recovery in this area. In one study, grip and pinch strengths reached better levels than before surgery within 6 weeks. In another study, however, grip strength and dexterity did not return to before-surgery levels until 25 weeks after open surgery. The scar may remain tender for up to a year.
• Peak improvement (the best level of improvement a patient can reach) may take a long time; in one study, it took an average of almost 10 months.

Physical Therapy. Physical therapy is very important to help rebuild wrist strength. While physical therapy does not reduce the recurrence (return) of symptoms or improve the long-term benefits of surgery, it does accelerate recovery after surgery. 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 has no benefits.

Complications and Long-Term Outcome

Treatment failure and complication rates of CTS surgery vary.

Complications after surgery may include the following:

• Nerve damage with tingling and numbness (usually temporary).
• Infection.
• Scarring.
• Pain.
• Stiffness. Loss of some wrist strength is a complication that affects between 10% and a third of patients. Endoscopy may have better results than open release. Some patients who have jobs requiring significant strength of the hand and wrist 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. These problems do not go away with surgery and can persist. Studies indicate that between 10 - 15% of patients change jobs after a CTS operation.

If pain and symptoms return, the release procedure may be repeated.

Reasons for procedure failure include:

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

Patients who had open release surgery appear more likely to require repeat operations compared with those who have had endoscopic surgery.

Procedures for Treating Surgical Failure or Recurring Symptoms

Neurolysis. In 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 within 3 months after surgery, after which improvement is unlikely. It is unclear if this approach offers any benefits over conservative measures to free the nerve from surrounding scar tissue.

Implants. In another procedure for recurrent carpal tunnel syndrome, doctors 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 cutting the nerve. Another procedure called vein wrapping uses grafts taken from veins to help protect the scarred nerves.

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Review Date: 4/1/2006
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital