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  • Updated 10.16.2023
  • Released 02.03.1998
  • Expires For CME 10.16.2026

Carpal tunnel syndrome



Carpal tunnel syndrome is the most common entrapment neuropathy, with a prevalence of about 270 per 100,000. The etiology is compression of the median nerve in the carpal tunnel. Clinical manifestations consist of intermittent hand pain, numbness, positional paresthesia, and nocturnal dysesthesia, and the syndrome is commonly associated with subjective grip weakness. Diagnosis is made based on clinical features and, often, electrodiagnostic studies. Ultrasonography has emerged as a useful and less invasive technique for evaluating carpal tunnel syndrome. Some predisposing factors include pregnancy, diabetes, rheumatoid arthritis, hypothyroidism, and amyloidosis. Treatment is conservative or surgical, depending on the severity of the symptoms. Endoscopic carpal tunnel release is associated with less scarring than open release but is more expensive and precludes visualization of the median nerve proper. Controversy continues about which surgical procedure is the best. In this article, the author discusses updates on diagnosis, treatment, outcomes, and implications in pregnancy

Key points

• Carpal tunnel syndrome is the most common entrapment neuropathy.

• Electrodiagnostic studies have a sensitivity of up to 95% for the diagnosis when detailed studies are performed.

• Peripheral nerve ultrasound imaging is proposed as a painless rapid screening test for carpal tunnel syndrome.

• In most patients, including elderly patients and patients with diabetes, surgical carpal tunnel release should be considered if conservative measures fail.

• Carpal tunnel syndrome could be an early manifestation of familial and wild-type transthyretin amyloidosis.

Historical note and terminology

The first description of a chronic median nerve entrapment at the wrist was by Paget (52) concerning a patient with a previous distal radius fracture (61). This was a severe entrapment accompanied by ulceration in the first three fingers. Paget noted recovery of the ulcerations with rest and increased symptoms with use of the hand secondary to nerve compression. Putnam first described the classic clinical symptoms of intermittent nocturnal hand paresthesias with subjective hand swelling and an improvement with shaking of the hand (58). Marie and Foix documented the thinning of the median nerve under the flexor retinaculum in a patient with bilateral isolated thenar atrophy in a postmortem study and suggested that transection of this ligament may have been therapeutic (43).

The first surgery for carpal tunnel syndrome was done in 1933 (35). Carpal tunnel syndrome received increasing attention in the 1940s and 1950s from both neurologists and surgeons. Simpson was the first to describe the increased distal motor latency of the median nerve stimulated at the wrist (65). Since then, increasingly refined nerve conduction techniques have been developed to demonstrate conduction slowing in the median nerve across the carpal tunnel. The development of clinical electrodiagnostic testing with EMG and nerve conduction studies in the 1960s added a valuable diagnostic tool. The use of high-resolution ultrasound imaging to study the median nerve in carpal tunnel syndrome was first published in 1992 (11); however, extensive literature has accumulated since the early 2000s.

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