What's New with Carpal Tunnel Syndrome?
Reading the news about carpal tunnel syndrome (CTS) is a lot like watching ping-pong. The ball keeps bouncing from side to side. What do we mean by this ping-pong analogy? Well, for a long time physicians relied upon clinical tests to make the diagnosis. But the evidence was back and forth in support and against these tests. They weren't reliable enough. They weren't valid. They didn't really prove there was compression on the median nerve causing the symptoms of hand pain and finger numbness and tingling that come with carpal tunnel syndrome.

Then a study group from the American Academy of Orthopaedic Surgeons released a report that recommended electrodiagnostic testing in order to confirm the diagnosis -- especially before doing any surgery. So everyone jumped from the side of long held beliefs that carpal tunnel syndrome could be diagnosed with a few special tests performed in the clinic to an understanding that the evidence pointed to the need for nerve conduction velocity (NCV) tests and electromyography (EMGs) studies to know for sure that the problem was carpal tunnel syndrome.

Now, electrodiagnostic tests have been called into question. The ping-pong ball has been lobbed onto the other side of the table again. There is now additional evidence that some people can have normal electrodiagnostic tests but clearly have carpal tunnel syndrome. Concern has been expressed that not treating patients (withholding treatment) because they have normal nerve conduction velocity and electromyography studies is not an acceptable approach.

In the meantime, another researcher explored the possibility of finding clinical criteria that can be used successfully to diagnose this condition. As a result, six items have been put together as clinical proof that carpal tunnel is the underlying problem causing the patients painful neurologic symptoms.

These include some of the former tests (e.g., Phalen's, two-point discrimination, Tinel's sign, numbness at night, muscle weakness) physicians used for years to diagnose carpal tunnel syndrome. Numbness at night and weakness of the thumb muscles are two additional criteria that can be used to diagnose carpal tunnel syndrome. A panel of experts agreed that these tests are reliable and further statistical analysis further validated the findings. The ball has just popped back over the net.

Researchers have also looked for other ways to reliably diagnose carpal tunnel syndrome. Ultrasound imaging has come up as one possibility. It's easy to use. It's inexpensive and it doesn't hurt. Ultrasound images show the inside of the carpal tunnel. Narrowing of the carpal tunnel, increased size of the nerve through the tunnel, and the presence of cysts or tumors or other anatomic changes can be seen. But we don't have normal values for cross-sectional views like this for the general (normal, healthy) population to use for comparison yet. That's a potential area for future study.

Okay, so we've got some updated clinical criteria now to use based on evidence when making the diagnosis. Patients always ask, "What's causing this problem?" Is it work related? Genetic? Structural? Despite many attempts to answer this question, we still don't know.

There is an ingrained belief in our country that typing on a computer keyboard for hours every day and using the hands for repetitive clerical activities is the root cause of carpal tunnel syndrome in the majority of cases. This hasn't ever been proven. We know for sure that regular, prolonged use of handheld vibratory tools like jackhammers and forcefully gripping tools like drills can contribute to carpal tunnel syndrome from pressure on the median nerve. But that's the extent of our scientific evidence that the work place is to blame.

Once the diagnosis has been made and confirmed, what next? Treatment for carpal tunnel syndrome has often been broken down into two categories: conservative (nonoperative) care and surgery. Nothing has changed here except new guidelines have been set forth by the American Academy of Orthopaedic Surgeons (AAOS) to help physicians decide when to recommend one over the other.

Here's where we pick up that game of ping-pong again. Until the recommendation came out that surgery should only be done when electrodiagnostic tests were positive, patients were treated conservatively for a period of weeks to several months. Surgery was done when conservative care failed to produce the desired results. But for a while now the recommendation has been for surgery as soon as electrodiagnostic testing proved positive.

Further study of the problem has yielded more evidence that conservative care is still the best approach. The chance that splinting, use of steroids (local injection or oral pills), and ultrasound treatments could work is worth the wait in terms of overall financial cost and outcomes. Sometimes a single steroid injection is all it takes. In other cases, several injections are needed. It's only when injections are no longer effective (or not effective at all) and other conservative measures fail to bring about results that surgery is advised.

We are almost to the end of the ping-pong game! It sounds like sorting out the best treatment is clear enough. That is until we realize there are two different ways to approach the surgery: open incision versus minimally invasive with endoscopic surgery. Studies are currently being done to compare the results using one method over the other. Results are measured using pain, function, return-to-work, and patient satisfaction.

For the most part, it looks like the long-term results are fairly equal between the two surgical approaches. After five years, the majority of patients come out looking about the same when using these measures. Early results might favor the endoscopic procedure simply because patients get their grip and pinch strength back faster and that translates to a faster return-to-work for some people.

When endoscopic techniques for carpal tunnel release first came out 20 years ago, there was some concern that patients would have more complications. Nerve and blood vessel damage were cited as the two major potential problems with the endoscopic approach. But once again, studies just haven't shown that there's a difference in safety between the two surgical methods. In the end, it becomes a personal decision by the patient based on the surgeon's best advice.

In summary, the current evidence available regarding the diagnosis and treatment of carpal tunnel syndrome boils down to these key guidelines:
  • Surgeons can use clinical tests to assess patients when making a diagnosis of carpal tunnel syndrome. Combining results of the six features mentioned gives the most valid diagnostic testing.
  • Patients can have true carpal tunnel syndrome without positive electrodiagnostic test results. Treatment should not be withheld on the basis of electrodiagnostic tests alone.
  • Conservative care is the first step for most patients. But anyone who doesn't improve within eight weeks using oral steroids or after three months with splinting should be considered for surgery.
  • Surgical approach (open incision versus minimally invasive endoscopy) is a matter of personal preference.

    Following the guidelines set forth by the American Academy of Orthopaedic Surgeons outlined in this article will result in the safe and effective treatment of carpal tunnel syndrome. Ninety-five per cent of patients handled this way had a successful result. No further treatment was needed. End of game!
    Kyle D. Bickel, MD. Carpal Tunnel Syndrome. In The Journal of Hand Surgery. January 2010. Vol. 35A. No. 1. Pp. 147-152.