Carpal Tunnel Syndrome - Causes

Autoimmune Diseases. In autoimmune diseases, the body's immune system abnormally attacks its own tissue, causing widespread inflammation, including, in many cases, the carpal tunnel of the hand. Such autoimmune diseases include rheumatoid arthritis, systemic lupus erythematosus, and hypothyroidism. Some experts believe that CTS may actually be one of the first symptoms in a number of these diseases. Studies also suggest that CTS patients with these disorders are more likely to have severe CTS that require surgery.

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Diseases that Affect Muscle and Bones. Arthritis, gout, and other medical conditions that damage the muscles, joints, or bones in the hand may cause changes that lead to CTS. In fact, in one 2000 study, susceptibility to muscle and bone diseases was the major risk factor for CTS in British women. Osteoporosis (loss of bone density), although not a direct cause of CTS, increases the risk for fractures of the wrist that can lead to CTS.

Injuries and Previous Surgeries. Injuries, fractures, and operations that affect the forearm, wrist, or hand may lead to CTS, sometimes many years after the event.

Structural Abnormalities. Inborn abnormalities in the bones of the hand, wrist, or forearm may contribute to CTS.

Chronic Kidney Insufficiency. People who undergo hemodialysis for chronic kidney damage (renal insufficiency) often experience a build-up in the hand of a certain type of protein called beta 2-microglobulin. This can result in CTS and the longer the duration of the hemodialysis the greater the risk. Certain drugs and procedures (particularly one called hemodiafiltration) are being investigated to reduce microglobulin build-up and delay the need for carpal tunnel surgery in patients undergoing long-term hemodialysis.

Other Diseases. A number of other medical conditions may cause or increase susceptibility to CTS:

Down's syndrome.
Amyloidosis (a progressive disorder of the connective tissues).
Acromegaly (a disease that leads to abnormally large hands and feet due to excessive growth hormone).
Tumor on the median nerve. (Removal of the tumor often resolves the CTS in such cases.)

Medications. According to case reports, a number of medications may possibly increase the risk for temporary CTS. They include certain medications that affect the immune system (such as interleukin-2), and anticlotting drugs (such as warfarin). There has been conflicting evidence as to whether corticosteroids and hormone replacement therapy may increase risk. More research is warranted before a causal association can be established.