Carpal Tunnel Syndrome in Emergency Medicine

Updated: Sep 08, 2016
  • Author: Jeffrey G Norvell, MD; Chief Editor: Trevor John Mills, MD, MPH  more...
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Overview

Background

Carpal tunnel syndrome (CTS) is a compressive neuropathy of the median nerve at the wrist. [1] The carpal tunnel is located at the base of the palm and is bounded on 3 sides by carpal bones and anteriorly by the transverse carpal ligament. Inside run the median nerve, flexor tendons, and their synovial sheaths. It is the most common entrapment neuropathy, with  repetitive, forceful angular hand movements or vibration placing persons at risk for the condition. Diagnosis is based on clinical history and findings, along with corroborating electrodiagnostic studies. [2, 3, 4, 5, 6, 7]

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Pathophysiology

Carpal tunnel syndrome (CTS) is caused predominantly by compression of the median nerve at the wrist because of hypertrophy or edema of the flexor synovium. Pain is thought to be secondary to nerve ischemia rather than direct physical damage of the nerve. [8]

See the images below.

Carpal tunnel syndrome. Carpal and Guyon tunnels. Carpal tunnel syndrome. Carpal and Guyon tunnels. Drawing showing the proximal level of the carpal tunnel delimited by the pisiform (P) and the scaphoid (S). The flexor retinaculum (medium gray region) forms the roof of the carpal tunnel and the floor of the Guyon tunnel. The palmar carpal ligament (dark gray region) forms the volar boundary of the Guyon tunnel. * = flexor pollicis longus tendon, * = flexor carpi radialis tendon. From Martinoli C, Bianchi S, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. Radiographics 2000; 20:S199-S217. Used by permission of the authors and RSNA.
Carpal tunnel syndrome. Carpal and Guyon tunnels. Carpal tunnel syndrome. Carpal and Guyon tunnels. Transverse 5-12-MHz ultrasound scan corresponding to the image above shows the proximal level of the carpal tunnel delimited by the pisiform (P) and the scaphoid (S). The flexor tendons and median nerve (MN) extend through the carpal tunnel, with the nerve lying palmar and radial. The flexor retinaculum (open arrowheads) forms the roof of the carpal tunnel and the floor of the Guyon tunnel. At the level of the pisiform, the ulnar nerve (U) courses medial to the ulnar artery (solid arrowhead) within the Guyon tunnel. * = flexor pollicis longus tendon. From Martinoli C, Bianchi S, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. Radiographics 2000; 20:S199-S217. Used by permission of the authors and RSNA.
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Epidemiology

Carpal tunnel syndrome (CTS) is the most frequently encountered peripheral compressive neuropathy. The prevalence of carpal tunnel syndrome in the United States is estimated at 3.7%, and the annual incidence is estimated at 0.4%. [9, 10] Early in the course of CTS, the neurologic findings are reversible. If untreated, CTS can result in thenar atrophy, chronic hand weakness, and numbness in the median nerve distribution of the hand. CTS is more prevalent in females than in males [11, 2]  and most common in middle age.

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