ERGONOMICS - About Carpal Tunnel Syndrome

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Carpal tunnel syndrome: A type of compression neuropathy (nerve damage) caused by compression and irritation of the median nerve in the wrist. The nerve is compressed within the carpal tunnel, a bony canal in the palm side of the wrist that provides passage for the median nerve to the hand. The irritation of the median nerve is specifically due to pressure from the transverse carpal ligament.

Carpal tunnel syndrome (CTS) can be due to trauma from repetitive work such as that of supermarket checkers, checkers in other types of stores, assembly line workers, meat packers, typists, word processors, accountants, writers, etc. Other factors predisposing to CTS include obesity, pregnancy, hypothyroidism, arthritis, and diabetes.

The symptoms of CTS include numbness and tingling of the hand, wrist pain, a "pins and needles" feeling at night, weakness in the grip and a feeling of incoordination.

The diagnosis is suspected based on symptoms, supported by signs on physical examination, and confirmed by nerve conduction testing.

Treatment depends on the severity of symptoms and the underlying cause. Early CTS is usually treated by modification of activities, a removable wrist brace and anti-inflammatory medicines. Caught early, CTS is reversible. If numbness and pain continue in the wrist and hand, acortisone injection into the carpal tunnel can help. Surgery is only indicated if other treatments have failed. In advanced CTS, particularly with profound weakness and muscle atrophy (wasting), surgery is done to avoid permanent nerve damage.

The surgical procedure is called a carpal tunnel release. It relieves the pressure exerted on the median nerve within the carpal tunnel. This surgical procedure is performed via a small incision using conventional surgery or a fiberoptic scope (endoscopic carpal tunnel repair).

Additional Information

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Intricate in design and function, the hand is an amazing work of anatomy. Form follows function in the hand; therefore, any injury to the underlying structures of the hand carries the potential for serious handicap. To reduce this risk, even the smallest hand injuries require a good medical evaluation. The hand consists of 38 bones; 10 metacarpal bones and 28 phalanges (finger bones).

Image Source: MedicineNet, Inc.Finger Anatomy: Fingers are easily injured, and broken fingers are some of the most common traumatic injuries seen in an emergency room. Finger fractures may account for up to 10% of all bone fractures. Because fingers are used for many everyday activities, they are at higher risk than other parts of the body for traumatic injury, including sports injuries, workplace injuries, and other accidents.

Understanding the basic anatomy of the hand and fingers is useful in understanding different types of finger injuries, broken fingers, and how some treatments differ from others. Fingers are constructed of ligaments (strong supportive tissue connecting bone to bone), tendons (attachment tissue from muscle to bone), and three  phalanges (bones). There are no muscles in the fingers; and fingers move by the pull of forearm muscles on the tendons. The three bones in each finger are named according to their relationship to the palm of the hand. The first bone, closest to the palm, is the proximal phalange; the second bone is the middle phalange; and the smallest and farthest from the hand is the distal phalange. The thumb does not have a middle phalange.

The knuckles are joints formed by the bones of the fingers and are commonly injured or dislocated with trauma to the hand.

• The first and largest knuckle is the junction between the hand and the fingers - the metacarpophalangeal joint (MCP). This joint commonly is injured in closed-fist activities and is commonly known as a boxer's fracture.
• The next knuckle out toward the fingernail is the proximal inter-phalangeal joint (PIP). This joint may be dislocated in sporting events when a ball or object directly strikes the finger.
• The farthest joint of the finger is the distal inter-phalangeal joint (DIP). Injuries to this joint usually involve a fracture or torn tendon (avulsion) injury.

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Fingernail: A fingernail is produced by living skin cells in the finger. A fingernail consists of several parts including the nail plate (the visible part of the nail), the nail bed (the skin beneath the nail plate), the cuticle (the tissue that overlaps the plate and rims the base of the nail), the nail folds (the skin folds that frame and support the nail on three sides), the lunula (the whitish half-moon at the base of the nail) and the matrix (the hidden part of the nail unit under the cuticle).

Fingernails grow from the matrix. The nails are composed largely of keratin, a hardened protein (that is also in skin and hair). As new cells grow in the matrix, the older cells are pushed out, compacted and take on the familiar flattened, hardened form of the fingernail.

The average growth rate for nails is 0.1 mm each day (or 1 centimeter in 100 days). The exact rate of nail growth depends on numerous factors including the age and sex of the individual and the time of year. Fingernails generally grow faster in young people, in males, and in the summer.

Fingernails grow faster than toenails. The fingernails on the right hand of a right handed person grow faster than those on their left hand, and vice versa.