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The main symptom of carpal tunnel syndrome is pain in your hand, and sometimes in your forearm. Symptoms can vary from mild to severe depending on how compressed the median nerve is. The symptoms are usually worse at night, but may also be noticed during daily activities, such as driving. Some people find that they drop things due to a weakened grip.
Specific symptoms of carpal tunnel syndrome include:
pain or aching in your hand and, in some cases, your lower forearm,
pins and needles, or a tingling or burning sensation in your thumb, forefinger, middle finger and the half of your ring finger nearest to your thumb,
numbness in these fingers, or part of your palm, may also develop if the condition becomes worse, and
a weakened grip in the affected hand, often affecting your thumb. In some people, there may also be wasting of the muscles at the base of the thumb.
The symptoms of carpal tunnel syndrome are caused by compression (squashing) of the median nerve. However, exactly why it happens is unknown. If a tendon that passes through the narrow carpal tunnel becomes inflamed and swells, it may put pressure on the nearby median nerve.
Carpal tunnel syndrome may also be caused by the following:
Bone conditions in the wrist, such as rheumatoid arthritis, can cause thickening of the ligament that covers the carpal tunnel.
Wrist injuries, such as joint dislocations and fractures, can narrow the carpal tunnel and put pressure on the median nerve.
Hormonal changes, such as an under-active thyroid gland (hypothyroidism) or an over-active thyroid gland (hyperthyroidism). Taking the combined oral contraceptive pill, and the menopause, can also disrupt the hormone balance and lead to carpal tunnel syndrome.
Other conditions, such as pregnancy, obesity, and diabetes mellitus are sometimes associated with carpal tunnel syndrome. Some of these conditions can cause water retention (oedema) which can lead to swelling in the wrist.
Rare conditions, such as cysts, growths, or swellings of the tendons or blood vessels that pass through the carpal tunnel.