What causes carpal tunnel syndrome?
Three nerves control the sensation and motor function of your arm—the median, radial and ulnar nerves. The median nerve controls sensation to the thumb, index finger, long finger and half of the ring finger. This nerve extends to the hand through a narrow, rigid passageway or “tunnel” in the wrist. The space in this tunnel is limited and if swelling of the soft tissues or changes in the bone occur; pressure starts to build.
Several factors can predispose individuals to carpal tunnel syndrome. In addition to repetitive movements, others include:
• change in occupation
• pregnancy
• taking oral contraceptives
• under active thyroid gland
• diagnosis of rheumatoid arthritis
• increased or changed use of your hands
Although these situations are not necessarily the primary cause of carpal tunnel syndrome, they can aggravate or contribute to the main cause. The disorder can also be caused by a cyst in the carpal tunnel, inflammation, fracture or dislocation of the wrist or by complications from diabetes. Some people are more likely to develop carpal tunnel syndrome simply due to genetics. Women are three times more likely than men to develop the syndrome and experts say this could be because they have smaller carpal tunnels than men.
What are the symptoms?
The most common symptoms of carpal tunnel syndrome are:
• Numbness or tingling in the palm of the hand, radiating to the fingers
• Tingling originating in the wrist, traveling into the hands
• Tingling originating in the wrist, traveling toward the arm, elbow or shoulder
• Sharp, piercing pain shooting through the wrist and up the arm
Symptoms may appear at first during the night, since many people sleep with flexed wrists. At first the symptoms may come and go, but as the condition progresses they can become more constant and severe, resulting in decreased grip strength and difficulty forming a fist. Some may not even be able to differentiate between hot and cold by touch.
How is it diagnosed?
Early diagnosis and treatment is important to avoid any permanent damage to the median nerve. Your physician will examine your wrist for signs of tenderness, swelling, warmth or discoloration. He may call for x-rays to rule out diabetes, arthritis or fractures.
There are specific tests physicians rely on to try to produce the symptoms of carpal tunnel syndrome, including:
• Phalen’s test. Also called the wrist-flexion test, this involves having the patient flex his or her hands to see if tingling or numbness is present.
• Tinel test. The physician taps on or presses on the median nerve in the patient’s wrist to see if tingling or a shock-like sensation occurs.
• Two-point discrimination. This test is used to see if the patient can differentiate between two non-sharp points in close proximity to each other.
Often electrodiagnostic tests are used to confirm carpal tunnel syndrome exists. In a nerve conduction study, electrodes are placed on the hand and wrist and the speed with which the nerves transmit impulses is measured. In electromyography, a fine needle is inserted into a muscle and the electrical activity is viewed to assess the severity of damage to the median nerve. An ultrasound can show impaired movement of the median nerve.
Treatment options
Initial treatment of carpal tunnel syndrome starts with resting the affected hand and wrist for at least two weeks, and avoiding activities that have been causing the numbness and pain. The wrist may be immobilized with a splint to avoid further damage from twisting or bending. Cool packs may be used to reduce any swelling.
From there, treatments may include:
• Non-steroidal anti-inflammatories (NSAIDS), such as aspirin or ibuprofen, to ease swelling and pain
• Stretching or strengthening exercises, usually performed after symptoms have improved, and supervised by a physical or occupational therapist
• Cortisone injections directly into the wrist to relieve pressure on the median nerve and provide some temporary relief
• Surgery, if symptoms do not respond to other treatments
How can I prevent carpal tunnel syndrome?
Carpal tunnel syndrome is becoming more and more common, but there are measures you can take to reduce your risk. The first step is to increase your awareness of how you use your hands and equipment throughout the day, and make some changes.
If you work at a keyboard or workstation:
• Center your work in front of you, with your forearms parallel to the floor or slightly lowered. If you stand at a workstation, make sure your work surface is waist high.
• Keep your hands and wrists in line with your forearms. If you work at a keyboard, tilt it to keep this alignment. Hold your elbows close to your sides.
• Avoid leaning on the heel of your hand or your wrist.
• Take small breaks every 10 or 15 minutes, and stretch your fingers, wrists and hands.
• Change your keyboard style. Some people prefer a split, V-shaped keyboard, which helps align the wrists at a better angle.
• If you work with equipment, change the way you hold the tool or switch hands periodically.
Carpal tunnel syndrome is becoming an increasingly common disorder, affecting over eight million Americans a year. As with any medical condition, the key to a successful treatment and recovery is early diagnosis. If you believe you are experiencing any of the symptoms described, make an appointment with your physician right away. Even if you are not currently experiencing symptoms but work in a field that is at risk for the disorder, take measures to improve your workstation to reduce your risk of developing carpal tunnel syndrome. tpw