Carpal tunnel syndrome is a progressively painful hand and arm condition, which may be accompanied by other symptoms such as tingling and numbness, caused by a pinched nerve in your wrist.
The carpal tunnel is a narrow passageway bound by bones and ligaments, which is located on the palm side of your wrist. This tunnel protects a main nerve to your hand and nine tendons that bend your fingers. Compression of the nerve produces the tingling and numbness, pain and, eventually, hand weakness that characterize carpal tunnel syndrome.
Carpal tunnel syndrome occurs as a result of compression of the median nerve. The median nerve runs from your forearm through a passageway in your wrist (carpal tunnel) to your hand. It provides sensation to the palm side of your thumb and fingers, with the exception of your little finger. It also provides nerve signals to move the muscles around the base of your thumb (motor function).
In general, anything that narrows, irritates or compresses the median nerve in the carpal tunnel space can lead to carpal tunnel syndrome. For example, a wrist fracture can narrow the carpal tunnel and irritate the nerve, as can the swelling and inflammation resulting from rheumatoid arthritis.
Factors have been associated with carpal tunnel syndrome, and may increase your chances of developing or aggravating median nerve damage include:
Chronic and inflammatory conditions such as hypothyroidism rheumatoid artritis, and nerve damaging conditions such as diabetes.
Alteration in body fluids causing fluid retention such as in pregnancy or obesity.
Making the same hand movements over and over, especially if the wrist is flexed (your hands lower than your wrists), or repetitive wrist movements.
Anatomic factors such as wrist injuries and bone spurs, as well as small carpal tunnel area (more common in women).
Smoking, because it can reduce blood flow to the median nerve.
Tingling or numbness in your fingers or hand, especially your thumb and index, middle or ring fingers, but not your little finger. This sensation often occurs while holding a steering wheel, phone or newspaper or upon awakening. Many people “shake out” their hands to try to relieve their symptoms. As the disorder progresses, the numb feeling may become constant.
Pain radiating or extending from your wrist up your arm to your shoulder or down into your palm or fingers, especially after forceful or repetitive use. This usually occurs on the palm side of your forearm.
A sense of weakness in your hands and a tendency to drop objects.