Carpal tunnel syndrome has been much in the news in recent years, as it has become better understood, and because of changes in the workplace in recent years which have tended to produce the syndrome.
The carpal tunnel is a groove running between the bones on the inside of the wrist from the arm into the palm of the hand. The median nerve runs through it along with blood vessels and tendons, and it is pressure on this nerve that causes the symptoms of the syndrome. The median nerve is one of three that carries sensory nerves from the hand and that supplies motor nerves to the intrinsic muscles of the hand. The other two nerves — the radial and the ulnar — have their own compression syndromes (see my posting about neuropathies), but since neither of them runs through the carpal tunnel, they are not involved in this particular syndrome.
The median nerve innervates the muscles of the thumb that are found in the prominence at its base, and carries sensation from the palm side of the thumb and the adjacent fingers down to half the ring finger, the half nearer the thumb. (The other half and the pinkie send their sensations along the ulnar nerve.) When pressure is increased in the carpal tunnel and squeezes the median nerve, the first symptom is generally numbness and tingling of the palm, the thumb, and the fingers down to the ring finger. Pain in the same area may also occur, and aching pain in the hand with some radiation up into the forearm is common, particularly at night. Weakness and atrophy (loss of muscle mass) of the muscles of the thumb can occur, but is generally a late sign after the numbness, tingling and pain have been present for a while. A test frequently used to diagnose the syndrome, the Tinel sign, consists of increased tingling when the wrist is tapped with a percussion hammer, or the doctor’s finger.
The most accurate diagnosis is made by doing electrodiagnostic testing of the median nerve and demonstrating delayed conduction of both the sensory and motor components of the nerve.
Several other conditions may predispose to the development of the syndrome, including rheumatoid arthritis, diabetes, hypothyroidism, and pregnancy. The syndrome tends to be more common in women than men, perhaps because of pregnancy and the higher incidence of rheumatoid arthritis in women than in men. Women may also be exposed to more hours of keyboard work at their jobs than men. Long hours spent at the computer seem to precipitate the syndrome in many cases.
The initial treatment should be the use of light wrist splints to hold the wrists in a neutral position, neither flexed nor up and back, since both motions increase the pressure in the tunnel. Mild pain medications such as acetominophen (Tylenol) or a nonsteroidal antiinflammatory (Motrin, Advil, Aleve) may also be prescribed. Some doctors will try vitamin B6, pyridoxine. Wrist supports should be used when at the computer. If the symptoms continue injections of a cortisone type drug into the carpal tunnel will often relieve the symptoms. I had carpal tunnel syndrome when I had active rheumatoid arthritis, and got immediate relief from such injections. Fortunately I had a mild case, both of the rheumatoid arthritis and the carpal tunnel syndrome.
If all else fails, there are surgical procedures to open up the carpal tunnel and reduce the pressure in that way. I have not had enough experience with patients having this procedure to be able to comment on its success rate.