Carpal tunnel syndrome is a pinched nerve in the wrist. Several nerves travel down the arm, across the wrist, and into the fingers to give us feeling in our fingers. The median nerve is one of these nerves and gives feeling to the thumb, index, long, and ring fingers. This nerve also helps move the thumb. As the median nerve crosses the wrist into the hand, it travels through a tight tunnel called the carpal tunnel. The tunnel is between 1 and 2 inches long and is surrounded by wrist bones on the back side, and a tight ligament on the top side. If swelling occurs inside this tunnel or the tunnel becomes tighter, the median nerve gets pinched and does not function properly. This loss of median nerve function causes numbness, tingling, or pain.
What are some causes? There are many known causes of carpal tunnel syndrome. Any injury to the wrist including a fracture, dislocation, or crush may cause swelling around the nerve. If the swelling is sufficient, you will feel numbness. Medical conditions which cause swelling or nerve dysfunction such as rheumatoid arthritis, diabetes, and thyroid disease may cause carpal tunnel syndrome. Swelling from pregnancy may cause this as well. Prolonged exposure to heavy vibration or direct impact to the palm can cause direct injury to the nerve. Despite all of these known causes, over half of patients who develop this condition have no identifiable cause.
What are the symptoms? Tingling in the thumb, index, long, or ring fingers is the most common complaint. It usually begins at night time and may awaken you from sleep. Many people also notice tingling while driving or reading the newspaper. Weakness sometimes leads to dropping items and in severe cases you may notice loss of muscle bulk in your palm which is referred to as thenar atrophy. Pain is an uncommon complaint early in carpal tunnel syndrome but may occur as pressure on the nerve increases.
How does the doctor confirm the diagnosis? A detailed patient history and exam including a description of your symptoms and other medical conditions are sometimes all that is needed. An x-ray is performed if there is any concern for trauma or arthritis. Confirmation of carpal tunnel syndrome is usually made with a nerve conduction study (NCT). This test measures the health of all of your nerves from upper arm to fingertip in order to rule out other possible causes of numbness.
What is the treatment? The goal of treatment is to reduce pressure on the nerve. This may be achieved with anti-inflammatory medication, vitamin B6, or wrist splints. Occasionally, a cortisone injection is recommended. If your symptoms don’t improve or your nerve conduction study shows severe compression, then surgery is recommended. The surgery involves opening the roof of the carpal tunnel so that it heals with less pressure on the nerve. A variety of surgical techniques may be used but all patients will initially have tenderness over the palm. Numbness may go away quickly in mildly pinched nerves but will take longer in patients with advanced symptoms. In severe cases or in elderly or diabetic patients, the numbness may not go completely away.