Overview of Carpal Tunnel

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Carpal tunnel syndrome is a common condition caused by compression, or entrapment, of the motor and sensory nerve in the wrist (median nerve), resulting in pain, muscle weakness, impaired reflexes, numbness, and tingling in the hand. Nerve compression is often associated with repetitive activities (e.g., typing, painting, hammering) that cause stress injury, swelling, and inflammation.

The carpal tunnel is a canal in the wrist through which fibrous connective tissue (tendons), nerves, and blood vessels pass. The transverse carpal ligament covers the carpal tunnel.

Incidence & Prevalence of Carpal Tunnel Syndrome

Incidence of carpal tunnel syndrome is highest in women over the age of 30. The condition may be more prevalent in people who use their wrists in repetitive activity (e.g., typists, computer operators, house painters).

Carpal Tunnel Syndrome Cause & Risk Factors

Carpal tunnel syndrome is caused by compression of the median nerve. The primary risk factor is a history of another musculoskeletal disorder. The condition develops most often in people who regularly use vibrating machinery and tools and those who use their wrists repetitively, such as:

  • Accountants
  • Artists–musicians, painters, writers
  • Assembly line workers
  • Bus, taxi, and truck drivers
  • Carpenters
  • Check-out clerks
  • Computer operators and programmers

Hobbies such as rowing, knitting, needlepoint, and gardening may also increase the risk for carpal tunnel syndrome. Other risk factors include underlying medical conditions, such as the following:

  • Arthritis
  • Amyloidosis (metabolic disorder)
  • Bone enlargement caused by overproduction of growth hormone (acromegaly)
  • Diabetes mellitus
  • Reduced thyroid gland function (hypothyroidism)
  • Pregnancy (may cause swelling of the extremities)
  • Tendon inflammation (tenosynovitis)
  • Uremia (condition in which the kidneys do not filter the blood sufficiently)
  • Wrist fracture

Signs & Symptoms of Carpal Tunnel Syndrome

The primary symptoms of carpal tunnel syndrome are pain and numbness in the thumb, index, and middle fingers that often worsen at night and may radiate to the upper arm. Symptoms usually occur near the palm of the hand. Other symptoms include muscle weakness in the hand and wrist, tingling, and impaired reflexes.

In advanced cases of carpal tunnel syndrome, shrinkage (atrophy) of the fleshy area at the base of the thumb may occur.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 01 Jan 2003

Last Modified: 03 Sep 2015