Carpal tunnel syndrome is a common disorder caused by nerve compression in the arm. The carpal tunnel -- located at the base of the palm, just above the wrist -- houses 9 tendons and the median nerve. This small area can be compressed by inflammation or direct pressure, and symptoms are relieved with decompression therapies.
CTS is caused by compression of the median nerve in the wrist. This nerve provides sensation to the thumb, index, middle and thumb-side of the ring finger. It also powers several thumb muscles. Symptoms of CTS include pain, tingling and numbness in the affected area of the hand, and eventually weakness in the thumb muscles. Atrophy -- shrinking -- of these muscles can occur with long-standing CTS, causing the muscles at the base of the thumb -- the thenar eminence -- to flatten. CTS is diagnosed with an examination, including tests that put the nerve in a compressed position. Electromyography -- nerve tests performed by inserting needles to stimulate the nerve -- helps determine the extent of the nerve damage.
Conservative treatments are tried first to decrease compression on the median nerve. Extreme bending of the wrist forward or backward increases pressure in the carpal tunnel, so splints are worn to hold the wrist straight to reduce pressure. Pre-made wrist cock-up splints may be bought and worn for this purpose. These splints typically come with the metal bar in 20 to 30 degrees of extension, which can make symptoms worse. Custom wrist splints can be made out of thermoplastic material by trained occupational and physical therapists, or the bar from the pre-made splint can be removed, straightened out and reinserted into the splint.
Splints are worn at night, and during periods of rest during the day. Sometimes these splints can be used during daily activities. Splints are worn for several weeks or months, until symptoms have improved. This treatment has been shown to be effective for short-term relief of CTS symptoms, particularly for mild to moderate cases.
Hand therapy, performed by a trained occupational or physical therapist may be prescribed for conservative management of CTS. Ultrasound is performed over the carpal tunnel to increase blood flow and decrease inflammation. Iontophoresis -- topical application of steroid medication -- is administered to the carpal tunnel via electrical stimulation. These treatments have been shown to decrease symptoms of CTS. Low-level laser treatments using red and infrared light are sometimes used by therapists to treat CTS, and early studies suggest this type of treatment may be effective in reducing symptoms.
Exercises help keep the flexor tendons and median nerve gliding smoothly through the carpal tunnel. Wearing a splint and not using the hand can affect the flexibility of the wrist and hand. Manual stretching is performed by the therapist to improve flexibility in the wrist. Although these treatments are widely used, they are not well supported by research.
Although conservative treatments may initially reduce pressure in the carpal tunnel, this improvement often plateaus within 3 months. Surgical decompression of the carpal tunnel may be needed if conservative treatments haven't worked. Carpal tunnel release is the most common hand and wrist surgery performed in the U.S.
Open carpal tunnel release is the standard procedure used for this surgery. A small incision is made over the carpal tunnel, and the transverse carpal ligament -- the "roof" over the tunnel -- is cut to relieve the nerve compression. According to a study published in 2012 in "The Open Orthopaedics Journal," 70 to 90 percent of patients have good to excellent long-term outcomes after carpal tunnel release.
Arthroscopic release of the ligament is sometimes performed. A tiny incision is made at the base of the hand, and a camera is inserted to view the ligament. A cutting tool is inserted into the same hole, or a second tiny incision is made in the palm. The procedure causes less damage to the surface of the palm, but open release allows the surgeon a better view of the ligament and nerve.