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CARPAL TUNNEL SYNDROME
Do your fingers feel numb or tingly when you perform strenuous activities with your hands? Do you wake up in the middle of the night because your hands feel like they are asleep and you need to shake them out to get the feeling back in them? If you answered yes to these questions, you may be experiencing symptoms of carpal tunnel syndrome (CTS).
Carpal tunnel syndrome is the most common nerve disorder affecting 4 to 10 million people each year and contributing to a great deal of time missed from work due to its sometimes debilitating symptoms. It is caused by compression of the median nerve as it passes through the wrist in a narrow passageway about the size of your thumb called the carpal tunnel. The median nerve travels from your neck down the arm and through this tunnel to provide sensation to the thumb, index, middle and half of the ring finger. It also sends impulses to the muscles in the palm that control certain thumb motions. This tunnel is bound by bones on 3 sides and a tight ligament on the 4th side giving it a limited amount of space. Passing through this tunnel along with the median nerve are 9 tendons that function to flex the fingers and the thumb. Anything that causes inflammation or swelling of any of these structures within this confined space compresses the median nerve. The result may be pain, weakness, or numbness in the hand and wrist, radiating up the arm.
The symptoms of CTS usually start gradually, with frequent burning, tingling, or itching numbness in the palm of the hand and the fingers, especially the thumb, index and middle fingers. These symptoms are aggravated by activities that put the wrist in a flexed or extended position for a prolonged period of time such as holding the steering wheel while driving or talking on the phone. Pain is another common symptom and can sometimes radiate up into the shoulder. Patients frequently experience these symptoms at night when they are awakened from sleep and feel like they need to shake out their hands to try and get the feeling back into them. As symptoms worsen, people typically begin to have difficulty grasping objects and notice a decrease in their grip strength. They also may begin to notice some atrophy of the thumb muscles that can occur in the late stages of the disease due to some permanent nerve damage.
Carpal tunnel syndrome is often the result of a combination of factors that increase pressure on the median nerve and tendons in the carpal tunnel, rather than a problem with the nerve itself. CTS may be found in patients who are pregnant, overweight or have various medical conditions, including thyroid disease, diabetes or arthritis, or injuries such as wrist fractures or sprains. Whether repetitive work activities cause carpal tunnel syndrome is still controversial, but it is thought that some strenuous repetitive hand activities, especially those involving vibratory motion, can worsen the symptoms. Just as frequently, the syndrome occurs on its own. It is thought that there is likely a genetic predisposition in most patients who suffer from CTS, meaning they simply have a smaller carpal tunnel.
Early diagnosis and treatment of carpal tunnel syndrome are important to avoid permanent damage to the median nerve. The diagnosis should be made by a physician based on an accurate description of the patient’s symptoms along with a detailed physical examination. A physical examination of the hands, arms, shoulders, and neck can help determine if the patient’s complaints are related to daily activities or to an underlying disorder and can rule out other painful conditions that mimic carpal tunnel syndrome. Routine laboratory tests may also be performed to help identify other medical conditions known to cause CTS. Often it is necessary to confirm the diagnosis by use of electrodiagnostic tests. In a nerve conduction study, electrodes are placed on the hand and wrist. Small electric shocks are applied and the speed with which nerves transmit impulses is measured. In electromyography, a fine needle is inserted into a muscle; electrical activity viewed on a screen can determine the severity of damage to the median nerve. Ultrasound imaging can show impaired movement of the median nerve. Magnetic resonance imaging (MRI) can show the anatomy of the wrist but to date has not been especially useful in diagnosing carpal tunnel syndrome.
Treatments for carpal tunnel syndrome should begin as early as possible, under a doctor’s direction. Underlying causes such as diabetes or arthritis should be treated first. Initial treatment generally involves resting the affected hand and wrist for at least 2 weeks, avoiding activities that may worsen symptoms, and immobilizing the wrist in a splint to avoid further damage from twisting or bending. If there is inflammation, applying cool packs can help reduce swelling. Anti-inflammatory medications such as ibuprofen or naproxen are commonly used to help relieve some of the symptoms by further reducing the inflammation. Steroids are sometimes injected directly into the carpal tunnel to provide some temporary relief of symptoms. Stretching and strengthening exercises can be helpful in people whose symptoms have abated. Most experts would agree that if symptoms persist after 6 months of these conservative measures, surgery should be recommended to relieve the pressure on the median nerve.
Surgery for carpal tunnel syndrome involves transecting the tight ligament that forms the roof of the tunnel. This relieves the pressure on the median nerve and increases the volume inside the carpal tunnel by around 25%. There are 2 basic techniques used today. The traditional open technique involves making a 1-2 inch incision in the wrist directly over the ligament and then cutting the ligament. The endoscopic technique involves making a smaller incision proximal to the ligament, inserting a small camera into the carpal tunnel to view the bottom surface of the ligament and then cutting it under direct vision. The advantage to the endoscopic technique is that it creates less scaring and has been shown to allow patients to return to their normal activities sooner than with the open technique. Both procedures can be done on an outpatient basis with minimal or no sedation along with some local anesthesia. The choice of which procedure should be performed should be made by the surgeon based on a variety of factors. Although symptoms may be relieved immediately after the surgery, most patients will experience some tenderness in the palm that will take a couple of months to completely resolve. Sometimes, a short course of supervised hand therapy will be ordered to help with the recovery process. Most patients are able to return to their normal activities within 2 weeks of surgery, but the length of recovery can vary based on how long the patient has had symptoms and how badly the median nerve was damaged.