Ask The Doctors: February 2013
Wrist numbness ... Can magnets relieve symptoms? ... Heat and cold therapy
Q. Iíve had arthritis in my right wrist for several years, but lately Iíve noticed a tingling or numbness there. Is it related to the arthritis or is it something else entirely?
A. Swelling or inflammation from arthritis can irritate or place pressure on nerves around the wrist and hand and cause sensations of pain, numbness, or tingling.††† Carpal tunnel syndrome, which is the entrapment or compression of the radial nerve at the wrist, occurs frequently in patients with rheumatoid arthritis. The ulnar nerve also may be affected at the elbow. Knowing which areas of your hand are affected by the numbness or tingling will help your physician determine which nerve is involved.† You should see your orthopaedist or rheumatologist promptly to determine the cause of your symptoms to avoid permanent nerve damage, and to make sure a more serious condition, such as vasculitis (inflammation of the blood vessels), is not present.
Q. A friend of mine wears a magnetic sleeve over his arthritic knee and he swears it has helped his symptoms. Iím skeptical. What do you think?
A. Magnetic devices are said to work by stimulating the release of the bodyís natural painkillers or by increasing blood flow to tissue; however, there is no scientific basis to conclude that small, static magnets can relieve pain or influence the course of any disease. In fact, the small magnets produce no significant magnetic field at or beneath the skinís surface. A study in Britain compared the effects of a magnetic device, a magnetic wrist strap, a copper bracelet, and a placebo (no magnetic effect) and concluded that magnetic and copper bracelets have no effect on pain, stiffness, or physical function in patients with osteoarthritis.† Magnetic treatment is generally considered harmless (although sometimes expensive) unless it causes you to forego other treatments.†
Q. Iíve been told to use both heat and cold in treating lower back pain, but Iíve often wondered how those two extremes could both be effective. Youíd think it would be one or the other. Can you explain?†
A. Studies have shown that ice massage and ice application are generally most helpful during the first 48 hours following an injury that strains the back muscles. After this initial period, heat therapy is probably more beneficial to the healing process. If the lower back is swollen or bruised, heat should not be used and it is better to use a cold pack to reduce the inflammation or swelling in the area.
The mechanism by which heat relieves pain is not exactly known, although researchers believe that heat inactivates nerve fibers which can force muscles into irritating spasms, and that heat may induce the release of endorphins, powerful opiate-like chemicals which block pain transmission. Heat appears to be better than cold for loosening muscles and increasing overall flexibility.† Strangely enough, cold therapy also can reduce muscle spasms, and cold is noted for killing pain, reducing swelling, and lowering metabolic activity. The pain-killing effect of cold is caused by its ďdeadeningĒ of nerve-cell activity. Hospital studies show that patients who use cold therapy on injuries tend to require less pain medication. Cold decreases muscle spasms by making muscles less sensitive to being stretched. The bottom line is that you should use the modality that works best for you. Whether you choose heat or cold, be careful not to apply it directly to the skin and not to leave it in place too long; ice applications generally should be left in place no more than 10 to 15 minutes at a time and heat no more than 15 to 30 minutes.