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Save Your Hands Carpal Tunnel Syndrome And Related Conditions Are Easier To Prevent Than Cure
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 FIG. 1A: Palmar view of the skeletal hand. |
 FIG. 1B: Proximal view of the carpal tunnel. |
The bellies of the muscles that flex the fingers (flexor digitorum superficialis and flexor digitorum profundus) lie in the anterior side of the forearm. The force of these muscles is transmitted to the finger bones via eight long tendons. At the carpal tunnel, these tendons are stacked on top of each other, with the median nerve above them. (See Fig. 2) In addition, the tendons of flexor carpi radialis and flexor policis longus also pass through the carpal tunnel. These tendons are enveloped in synovial sheaths, which facilitate the tendons'gliding motion of flexion and relaxation.
 FIG. 2A: Carpal tunnel proximally, including tendons and nerve. |
 FIG. 2B: The palmar aspect of the hand, showing the course of the median nerve. |
At this point, there may be pain, stiffness, and numbness in the hands and fingers caused by pressure within the carpal tunnel. This condition may be diagnosed as tendinitis or repetitive motion injury. When prolonged swelling of the tendons and irritation of the median nerve results in impairment of the median nerve function, full-blown carpal tunnel syndrome develops. The symptoms of CTS include persistent numbness and pain in the hands that is unrelieved with rest. In advanced cases the muscles of the thumb, which are innervated by the median nerve, may atrophy.
It is often difficult to successfully treat CTS. Anti-inflamatory medication may be useful, but cannot be used over a long period of time. Direct injections of anti-inflammatory steroids into the wrist area is painful, and, again, is not a procedure that can be repeated frequently. A surgical approach is to lengthen the ligament forming the palmar boundary of the carpal tunnel, thereby increasing the volume in the tunnel. As this surgery has gotten more refined with arthroscopic techniques, it is quite often successful. However, given that a great deal of pain and restriction of motion may lead up to this surgery, it's better to consider prevention rather than cure!
To develop a plan to prevent RSI, think again of how this cycle of injury develops by irritation of tendons and nerves through repeated motion. Obviously, avoiding repetitive movements is one way to minimize the danger of developing RSI. However, there are other factors to be considered as well. Irritation of tendons and nerves often starts because there is a poor blood supply to the hands. When blood supply is restricted by static body posture and/or poor body mechanics, the danger of developing RSI is increased.
Prevention of RSI includes avoiding repetitive motion whenever possible, taking care to stretch stressed areas or balance repetitive motions when you can't avoid them, using good body mechanics, and resting appropriately. Repetitve strain can be avoided!
 FIG. 3A: Rock and glide with hands under body. FIG. 3B: Rock and glide in side-lying position |
Working on a keyboard In the days before computers, when typewriters were in use, CTS was rare. Typists' hands were always in motion, moving slightly up and down the keyboard, and suspended above it. With computer keyboards, we are much more likely to rest our hands when we type. RSI may easily develop from the combination of enforced stillness and the possibility of restricting circulation. This is exacerbated when the hand or wrist rests on a hard surface.
 FIG. 4A: Hands in motion on typewriter. |
 FIG. 4B Hands in motion on keyboard, base of hand resting. |
 FIG. 4C: Hands in motion on keyboard, base of hand in air. |
It may seem that one solution, then, is to rest the hands on a soft surface! Soft rests have been developed to put under the base of the hand and wrist when using a keyboard. Initially these may provide some relief from RSI symptoms. However when the base of the hand is rested on a soft surface the bones on the sides of the tunnel sink in and the central span of the tunnel may receive more pressure.
If you use a keyboard treat it like a typewriter. If it is adjustable set it to require more force. Keep your wrists above the keyboard. This usually requires lowering the keyboard below the desk surface height, easily accomplished with a sliding keyboard tray. Additionally, using a chair with arms that support the elbows allows the wrists to have more mobility.
 FIG. 5A: Resting the wrist on a hard surface may feel uncomfortable over the bones, but protects the carpal tunnel. |
 FIG. 5B: Resting the wrist on a soft surface feels good over the bones, but puts ore pressure on the carpal tunnel. |
A second kind of RSI problem can occur when the base of the hand at the little finger rests continually on either a hard or soft surface. The ulnar nerve is relatively close to the surface of the body at the medial side of the palm, and can be pressed against the hamate bone when this part of the hand is continually pressed against some surface, especially if weight rests on it. Since this doesn't involve restriction at the carpal tunnel, it's often overlooked, but pain, numbness, and tingling in the ring finger and little finger can often be traced to compression in this area.
Wrist extension is more harmful than flexion The carpal tunnel is under the least strain when the wrist is near a neutral position. When the wrist is flexed, compression on the carpel tunnel is increased. However, when the wrist is extended compression on the carpel tunnel is three times as great as when the wrist is flexed.
 FIG. 6A: Wrist flexion. Carpal tunnel pressure.
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The problem of the opposable thumb Our prehensile thumbs allow us much greater dexterity than other creatures. However, overuse of this gift may contribute to RSI. Remember that the muscles that allow opposition of the thumb and fifth finger (opponens pollicis, opponens quinti digiti minimi), as well as the intrinsic flexors of the thumb and little finger, arise from the carpal ligament. Prolonged use of these muscles may result in chronic contraction. This chronic contraction may also affect the flexibility and resilience of the carpal ligament. Observe that when you bring the thumb and little finger together, the base of the hand narrows. This narrowing compresses the carpal tunnel area. When this narrowing becomes chronic, the carpal tunnel is chronically restricted.
Two kinds of hand motion involving the thumb can be hazardous. Gripping, using all fingers of the hand and the thumb, requires contraction of the tendons that go through the carpal tunnel. However, it doesn't restrict the carpal ligament in the same way as do opposition or pinching movements, which involve the motion of the thumb toward the midline of the hand. Both can produce RSI symptoms, though, and prolonged use of either should be avoided. When you are working on clients avoid using a lot of kneading or pinching movements. Watch for unconsciously holding the hand in a flexed position with the base of the hand narrowed. Avoid this.
Pronation and Supination Immediately proximal to the hand are the ulna and the radius. In the motions of pronation and supination the full length of the radius rotates, but the rotation is of a different kind at each of the two ends of the radius. At the elbow end of the forearm the radius rotates around its own axis within the annular ligament. At the wrist end of the forearm the radius rotates around the ulna. This functional difference between the two ends makes the shafts of the two bones move closer to each other in pronation and away from each other in supination. In pronation, the radius is crossed over the ulna. The muscular contraction required for this movement increases pressure in the forearm, and may restrict the free play of muscles and the blood supply to the forearm and hand.
You're probably already aware, though, that most of the activities we do with our hands require a pronated position. How can we offset the possible restrictive effects of prolonged pronation? Any degree of movement toward supination will help. Study the way you use your hands in bodywork to see if there are times you could bring your forearm to a neutral (thumb up) position rather than full pronation. If you have had trouble with RSI and use a computer a lot, a pyramid keyboard may also help. And always, frequent small variations in hand position reduce repetitive strain.
Distal restriction of nerves and vessels Irritation of nerves and restriction of blood vessels may also occur in both the elbow and the shoulder. Compression can occur at the elbow when it is flexed to less than 90 degrees. This may reduce circulation to the hand. Poorer nutrition and oxygenation, the result of reduced circulation, lead to more tissue irritation in the forearm and hand. Of course, you don't have to avoid such motions entirely, just avoid using them for extended periods of time. Adjust bodywork tables, computer chairs and keyboards, and the driver's seat and steering wheel of your car so the elbow can work at greater than 90 degrees.
Also avoid resting the elbows on a hard surface, especially if they are flexed to greater than 90 degrees. This motion extends the ulnar nerve where it runs between the olecranon of the elbow and the medial epicondyle of the humerus, and it is more vulnerable to repetitive stress at this point.
An even greater hazard is restriction at the shoulder. The roots of the nerves of the forearm and hand arise from the neck and run underneath the clavicle at the shoulder. This area also contains the main blood vessels for the arm. When the shoulders are rounded, or there is tension in the muscles of the neck and upper shoulders, these important vessels and nerves may be restricted. Thoracic outlet syndrome, sometimes seen as a structural problem and sometimes as a form of RSI, may be caused by constriction of the nerve roots between the scalene muscles and the first rib. Even when TOS is not identified, compression and restriction here may make the nerves and tendons more vulnerable at the wrist and hand.
 FIG. 7A: Areas of frequent nerve and vascular impingement. |
To minimize the risks of problems in this area, avoid "hunching over" when you work. Keep the shoulder girdle relaxed, and your neck straight. Watch out for "wearing your shoulders around your ears."
In sleeping let your elbows be extended more than 90 degrees. We all change positions in sleep 12 - 15 times a night, so the position you start in is not where you spend most of the night. Yet, if you begin the night with your hands supinated and elbows extended that may be 45 minutes of better position. Every little bit makes a difference. If you wake during the night you can get another 45 minutes or so. If you need to go to sleep on your side, avoid having your elbows flexed and your wrists curled inward. Don't sleep with your hands under your head.
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How to Reduce Hand Strain: Twelve Big Hints 1. Vary your tasks. Mix several activities in the course of a day to reduce repetitive activity. 2. When performing a repetitive task frequently vary the way you are using your hands. Even small variations help. 3. Avoid working with your elbows bent at an angle less than 90 degrees. Too much bend at the elbow compresses blood vessels and nerves. 4. Whenever possible, keep your wrists at an angle near neutral. Flexion puts strain on the carpal tunnel. Extension places three times the strain as when the wrist is flexed. 5. Don't rest your wrists on surfaces, whether the hand is in neutral or in pronation. Resting the hand for long periods of time compresses the carpal tunnel and other vulnerable structures. 6. When you must use the hand in pronation, try to vary this with motions that bring the hand into thumb up position. When you are able to rest your hands, rest them in supination. 7. Minimize time spent contracting or narrowing the palm of the hand, as in opposition and pinching movements. This position contributes directly to carpal tunnel pressure. Adjust your grip position so the thumb doesn't close tightly across the fingers. 8. Keep your shoulders relaxed and your neck straight as much as possible to minimize pressure on nerve and vessel structures distal to your hands. 9. Breathe! It increases relaxation and blood oxygenation. 10. If you use a computer for several hours a day, then own two or three different mouse styles. Changing your mouse frequently and adjusting the angle of your hands often will help reduce repetitive strain. 11. Get regular exercise. One factor which may contribute to RSI is low cardiovascular condition of the body. Give your hands every chance to receive good blood flow. 12. If you experience RSI symptoms in your job, minimize hobbies which require intensive hand movements. Play soccer rather than racquet sports. Sing rather than play the guitar. |
Cailliet, R., Hand pain and impairment, Edition 4, 1994 F.A. Davis, ISBN 0-8036-1619-8
Cailliet, R., Neck and arm pain, edition 3, 1991 F. A. Davis, ISBN 0-8036-1610-4
Lester, B., The Acute Hand, 1999 Simon & Schuster, ISBN 0-8385-0258-X
Wilson, F. R., The Hand, 1998 Random House, ISBN 0-679-41249-2
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