Hand
What is the carpal tunnel?
The carpal tunnel is located under the base of your palm. It has rigid, unyielding boundaries: The back and sides of the carpal tunnel is made up of the bones of your wrist. The front of the carpal tunnel, just under your palm, is made up of a very thick ligament, the transverse carpal ligament. Your median nerve is the nerve that provides sensation to your thumb, index finger, middle finger and half of your ring finger. It runs through the carpal tunnel along with nine tendons that move your fingers and thumb, and the tendons’ lining, which is called the tenosynovium.
What is carpal tunnel syndrome?
Carpal tunnel syndrome occurs when the median nerve becomes compressed in the carpal tunnel. As the boundaries of the carpal tunnel are rigid, it has a limited amount of space. Therefore, anything that takes up too much space in the carpal tunnel can compress and damage the median nerve. Carpal tunnel syndrome is, pure and simple, a space problem: there’s too much stuff in too little space. The most common thing that takes up too much space is the tenosynovium (tendon lining), which can swell up.
What are the symptoms of carpal tunnel syndrome?
The symptoms of carpal tunnel syndrome come from irritation of the median nerve. Your median nerve supplies sensation to your thumb, index finger, middle finger and half your ring finger. It also controls the muscles at the base of your thumb.
People with carpal tunnel syndrome feel that their thumb, index fingers, middle finger, and occasionally the ring and small fingers are "numb", “asleep", or have "pins and needles" in them. This is often worse at night and when driving, writing or gripping objects (cell phones, heavy labor, etc). As carpal tunnel syndrome advances these fingers may permanently lose sensation. With more advanced carpal tunnel syndrome the muscles that move the thumb may not work well, and over time can even atrophy (die).
Carpal tunnel syndrome not uncommonly involves the small finger, but only when other fingers involved. If it’s only your small finger involved, then you probably have cubital tunnel syndrome (compression of the ulnar (funny bone) nerve around the elbow).
Any time you flex your wrist down, towards your palm, the space for the median nerve is decreased. Prolonged wrist extension, such as occurs during long bike rides, may also decrease the space available. Carpal tunnel syndrome is usually worst at night, or upon awakening in the morning because we all sleep with our wrists flexed down. If you wake up in the middle of the night with your hand numb or hurting, and have to "shake out" your hand before you can get back to sleep, you’ve got carpal tunnel syndrome.
This is why splinting the wrist at night often helps people with mild carpal tunnel syndrome – it keeps the median nerve from getting pinched while you sleep. The other reason why carpal tunnel syndrome is worst at night is because we tend to swell more at night. This swelling takes up space, further compressing the median nerve.
How is the diagnosis of carpal tunnel syndrome made?
The diagnosis of carpal tunnel syndrome is made by history and physical examination (ie. by talking to you and examining your arm). A symptom that is classic for carpal tunnel syndrome is waking up in the middle of the night with your hand tingling or "numb". If you flick your wrist to try to get rid of the numbness, you almost certainly have carpal tunnel syndrome. A thorough physical examination can evaluate the state of your nerves. There are other places in the arm where the median nerve can be compressed, which can lead to symptoms very similar to carpal tunnel syndrome. In unusual cases, these other potential sites of entrapment should be evaluated because they will not be relieved by a carpal tunnel release. It is also important to determine whether or not the ulnar (funny bone) nerve is involved.
Nerve conduction studies are usually obtained, mainly to confirm the diagnosis of carpal tunnel syndrome. However, these studies are not perfect. In fact, they fail to diagnose approximately 20-33% of people with carpal tunnel syndrome.
In the event that your history and physical examination strongly suggests carpal tunnel syndrome, but the nerve conduction study is negative, a steroid injection is indicated. An injection into the carpal tunnel is probably a better diagnostic test than the nerve conduction study. If the injection helps your problem, even for only a few days, then you almost certainly have carpal tunnel syndrome.
How is carpal tunnel syndrome treated?
Unless your carpal tunnel syndrome has been around for a long time, leading to permanent nerve damage, initial treatment is often wrist splinting at night.
If that doesn’t work, carpal tunnel syndrome should be cured by carpal tunnel release, which is an outpatient procedure. During a carpal tunnel release, the transverse carpal ligament that covers your median nerve at the wrist is cut. By cutting this ligament 25% more room is created for your median nerve, relieving the pressure on it, stopping the progression of the disease and allowing it to heal. Unless irreversible nerve damage is already present, this decreases the symptoms of carpal tunnel syndrom in over 95% of patients.
Are all Carpal Tunnel Releases the Same?
There are different types of carpal tunnel releases. In the past, surgeons used long incisions that crossed the wrist crease. However, these lead to more “surgical moribidity" (pain, stiffness, etc) than is necessary. Many surgeons use a ‘mini-open’ release, which is a smaller incision in the palm that doesn’t cross the wrist crease. This has less pain associated with it.
Endoscopic carpal tunnel releases are done through smaller incisions, with less pain, less suffering and a quicker return to work. Endoscopic carpal tunnel release is associated with higher levels of physical functioning and fewer days to return to work compared to open carpal tunnel release.1-3 There are two types: 1) A one-incision endoscopic carpal tunnel release and 2) a two-incision endoscopic carpal tunnel release. The two-incision endoscopic carpal tunnel release puts a scar in both the wrist crease and in the palm. While it’s an improvement over the open carpal tunnel release, the palmar wound still causes additional discomfort.
The least invasive technique for carpal tunnel release is a single-incision endoscopic carpal tunnel release. The incision is made in your wrist crease, which tends to hide it, and there is no incision in your palm. Because of this, there is decreased palmar tenderness, and most patients return to work (and other worthwhile activities) sooner following single-incision endoscopic carpal tunnel release compared to following two-incision endoscopic carpal tunnel release.3
References:
1) Feuerstein M, Burrell LM, Miller VI, Lincoln A, Huang GD, Berger R: Clinical management of carpal tunnel syndrome: a 12-year review of outcomes. Am J Ind Med 35:232-45, 1999.
2) Kerr CD, Gittins ME, Sybert DR: Endoscopic versus open carpal tunnel release: clinical results. Arthroscopy 10:266-9, 1994.
3) Palmer DH, Paulson JC, Lane-Larsen CL, Peulen VK, Olson JD: Endoscopic carpal tunnel release: a comparison of two techniques with open release. Arthroscopy 9:498-508, 1993.
What can I expect after Endoscopic Carpal Tunnel Release?
Because I inject numbing medicine into the wound, your hand will probably be numb for the entire day of surgery. You can type and use computers as much as you want starting the day after surgery. You can do as much other activity as you want, but if you want to minimize pain and swelling than you should probably avoid heavy lifting and gripping for 4-6 weeks. You won’t damage yourself, but this stress will cause extra pain, discomfort and swelling that most people would rather avoid. However, if you don’t mind pain and swelling and need to perform work or other activies, that’s fine.
If you do develop this pain over the base of your hand (it’s called ‘pillar pain), you can expect it to go away on its own over a few months. Or I can inject it and usually make it go away in a few days.
Sometimes the hand swells on the day of surgery, causing the dressing to become too tight, like a tourniquet. The dressing is a white bandage with an ace wrap over it. You can unwrap and rewrap the ace wrap. If you think the white bandage is too tight, take a scissor and cut ½ of the bandage on the back of your hand, not over the palm. That will take care of the problem.
Please keep the wound clean and dry for one week. Bathing is safer than showering. Wrap a towel around the dressing in case any water gets in, then place a plastic bag over your hand and secure it tightly with rubber bands. After 4 days you can remove your dressings and get your incision wet in the shower. Blot it dry. There are no stitches to remove (they’re buried and absorbable). There are little pieces of tape over your wound. The longer they stay, the nicer the final wound may look. They’ll fall off when they’re ready. Please don’t submerge your incision under water (like swimming, or putting your hand under water while doing dishes) for 10 days after surgery.
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