What is Carpal Tunnel Syndrome? Carpal tunnel syndrome is a syndrome (a group of signs and symptoms that occur together and characterize a particular abnormality) that usually has as its main symptom numbness of the thumb, index finger, and long finger. The nerve that is involved is the median nerve (see illustration above). Patients usually complain of numbness and tingling at night that wakes them up; often they can shake their hand and make it better. Numbness can also be a problem when driving, reading the newspaper or a book, or any activity that requires the hands to be held elevated for a period of time. Patients often have pain in their hand, but characteristically it is hard for the patient to say exactly where the pain is located (this is not due to any fault of the patient's, but is a characteristic of compression on the nerve). There can be referred pain in the forearm, upper arm, shoulder, or higher. The presentation of symptoms is rather varied and overlaps other problems in the neck, shoulders, arm, and hand. There can be many other associated symptoms, but they are quite varied and can be confusing. Therefore, it is best if the diagnosis is made by a physician familiar with hand problems, such as a hand surgeon. In my own practice, about 50% of the patients who come in thinking that they have carpal tunnel syndrome in fact do not have it.
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Median nerve (in pink) as it goes to your fingers |
What is the anatomy of the carpal tunnel?
We need to understand the anatomy of the carpal tunnel in order to understand what causes it. Here are some diagrams that I have drawn to help you understand what causes it. The carpal tunnel is located at the base of the hand, just distal (closer to the fingertips) to the wrist crease:
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It is important for you to know that the problem is not in the forearm: it is in the base of the hand.
Here is an enlargement of the cross-section from the above diagram:
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This cross-section is from an MRI of one my patients. The carpal (Latin for "wrist") tunnel is a real tunnel, formed on the top by the transverse carpal ligament, which stretches from the a ridge on the trapezium (one of the bones of your wrist) to the hook of the hamate (see above), a protrusion from the hamate, another of your wrist bones. The sides are formed by the trapezium and the hamate, and the floor of the tunnel is formed by the trapezoid and capitate bones. Inside the tunnel are the tendons that go to your fingers and the median nerve, which supplies sensation to the thumb, index finger, long finger, and the radial side (thumb side) of the ring finger. It also runs the small muscles (intrinsics) of the thumb. (Just in case you wanted to know, the ulnar nerve supplies the rest of the ring finger and the little finger.)
What causes carpal tunnel syndrome?
Carpal tunnel syndrome is due to median nerve compression within the carpal tunnel, as increased pressure causes decreased blood flow to the nerve. Here is a simple experiment to help demonstrate this concept (I probably had you do this in the office): pinch two fingertips together. Note how the fingertips go white, because you have squeezed the blood out of the tissues. This is the mechanism of carpal tunnel syndrome. Whenever you feel numbness in your fingers due to your carpal tunnel syndrome, you have so much pressure within the confines of the carpal tunnel you have squeezed the blood supply of the nerve so much that it cannot support nerve function. This increased pressure comes from swelling (edema) of the tissues surrounding the tendons called the synovium. This swelling may be due to injury to the synovium from overuse, trauma, or other causes such as metabolic disturbances (endocrine disorders, pregnancy, menopause). We are not sure of the mechanism of overuse, but it appears to be related to exceeding the material properties of the capillaries, somewhat similar to a paperclip breaking when you bend it back and forth too many times. The histology (examination of the cells of tissues under a microscope) of synovium in carpal tunnel syndrome from overuse has shown edema (increased fluids between the cells) and fibrosis (scarring in the tissue) apparently from micro tears. Contrary to what many people think, there is little (<5%) of tenditis in the tendons of carpal tunnel syndrome.
What can you do about carpal tunnel syndrome?
The way that I treat carpal tunnel syndrome is described below. First, a brief explanation. I am going to outline my standard treatment approach to most hand problems, and then explain how each part either applies or doesn't apply to carpal tunnel syndrome specifically. This may help you to understand both the things that I am going to do, and also some of the incorrect things you may have been told about it. Note: every time you cross a line in this hierarchy, things get a bit more serious:
1 Diagnosis: we have to make sure that we are really dealing with carpal tunnel syndrome. Remember, many patients are referred to me for carpal tunnel syndrome that actually have another problem.
2 Patient education: so that you can take charge of your own health! This website is an important part of patient education, and we spend a lot of time on this in the office.
3 Activity modification: this
approach can be quite effective, if it can be applied, but many times it cannot.
If your problem is from a combination of fairly normal (but possibly rather
vigorous) use, coupled with normal aging processes, it may not be a very effective
approach. We will discuss your particular situation in the office.
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4 Anti-inflammatory medications, splints,
hand therapy: Night time splints may help with night time symptoms,
but rarely are effective enough on their own. Splints during the day may be
somewhat helpful, but they are rather obnoxious to wear, most patients give
them up after a while, and rarely are effective enough on their own. Hand
therapy is about the same: helpful, rarely completely effective. Antiinflammatory
medications are the same. One interesting question is why they help at all,
if this is not an inflammatory problem. It would apprear that they help to
stabilize membranes in the capillaries so that not as much fluid leaks out
of them, decreasing edema.
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5 Injections: these can be very
effective, but usually not permanently. In fact, based on studies in the literature
(Green)
the best use of the injection may be to determine if you will have a good
result from surgery. The injection can be done in a way that is almost painless.
I am not saying this on my own: I am repeating what patients tell me about
how they felt from one of my injections. I have a special technique; talk
to me about it. Virtually every patient tells me that the injection hurt a
lot less than they expected.
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6 Surgery: I put two lines between Step 5 and Step 6 because we have now come to the big S word: "Surgery". This word frightens most patients, but it should not frighten you. The surgery takes about 20 minutes, can be done under a local or a light general anesthesia (according to patient preference), is an out-patient procedure, has few risks, and usually results in complete resolution of pain and (if you have not put it off until the numbness is constant) significant or complete resolution of numbness. It is still surgery, and may be considered major surgery by some; it does have risks, as does any surgical procedure. We should talk about the risks and your health in the office. A website is not an adequate place to discuss surgery, except to say that it can be part of the management of carpal tunnel syndrome.
What can you expect? Patients who have symptoms that come and go, but still completely resolve at some time during the day, can expect that almost all of the symptoms will be gone the day after surgery. If you have waited so long that you have some degree of numbness all the time ("fixed numbness"), you will find that your sensation goes to as good as it has been recently, and then over weeks to months, will improve. It is impossible to predict how much sensation will return, which is why surgery is recommended before fixed numbness occurs. If you are going to improve, you should get some painful or obnoxious sensations in your hand a week or three after surgery. This is a good sign: your nerve is waking up! It is a bit like your foot waking up after you have sat on it too long.
Predicting the future is impossible, so no one can predict what your recovery might be like. However, the past is an excellent guide to the future, and the above comments are based on what has happened in my patients in the past.
If you want to read what real patients have experienced, a number of my patients who have had surgery have recorded their comments and experiences here. If you are thinking of having surgery, especially if you are wondering about doing both hands at the same time, you should read that page. |
Some patients have heard about Endoscopic Carpal Tunnel Release, a form of endoscopic surgery. Dr. Nelson is quite familiar with this technique, but does not recommend it. For more (a very complex question), click here.
Carpal tunnel syndrome is very common, so there is a lot written about it. You can choose from:
American Association of Orthopedic Surgeons: CTS Patient Education Brochure.
American Society for Surgery of the Hand: CTS Patient Education Brochure.
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Would you like to search the medical library of the
National Library Medicine for scientific papers on this topic? Just
click on
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Remember the admonition from the Patient Education Links Page: the Internet has a lot of information, much of it incorrect. I have reviewed the sites that I have linked to, and have only linked to sites when I personally know the surgeon who posted it, or am a member of the organization that posted it. However, I may not agree with all that is on that site, and it may have changed since I reviewed it. If any of the information is not consistent with what I have told you, please download the material and bring it in.
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