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Clinical Review Clinical Review

Carpal tunnel syndrome

BMJ 2007; 335 doi: (Published 16 August 2007) Cite this as: BMJ 2007;335:343
  1. Jeremy D P Bland, consultant in clinical neurophysiology
  1. Kent and Canterbury Hospital, Canterbury CT1 3NG
  1. Jeremy.Bland{at}

    Summary points

    • Carpal tunnel syndrome is the commonest cause of nocturnal hand paraesthesias and should be suspected in any patient with this symptom, whatever age

    • Initial treatment should be with neutral angle splinting at night; milder cases may be treated with local steroid injection before further investigation

    • Refer more severe cases—those with thenar weakness, sensory deficit, and daytime symptoms—for nerve conduction studies and possible surgery

    • Either open or endoscopic surgery may be used depending on availability of local expertise

    Why should I read this article?

    Carpal tunnel syndrome (CTS) is the commonest peripheral nerve problem in the United Kingdom and has considerable employment and healthcare costs. If recognised early it is readily treatable. No established UK guidelines exist for diagnosis and management, but the American Academy of Neurology issued guidelines in 1993, which remain current as no major recent advances have occurred.1

    What causes carpal tunnel syndrome?

    Carpal tunnel syndrome results from compromise of median nerve function at the wrist caused by increased pressure in the carpal tunnel, an anatomical compartment bounded by the bones of the carpus and the transverse carpal ligament. Although the ends of the tunnel are in free communication with the surrounding tissues, tissue pressure in the tunnel is much higher in patients with CTS (32-110 mm Hg, depending on wrist position) than in patients with normal wrists (2-31 mm Hg.2 Pressures are raised by wrist flexion and extension, and finger flexion.

    Intermittent or sustained high tissue pressure in the tunnel impairs microvascular circulation in the median nerve and leads to spurious generation of action potentials, local demyelination, and ultimately axonal loss. It may also stimulate the proliferation of subsynovial connective tissue in the tunnel, according to pathological studies of CTS.3 Anything that reduces the dimensions of the tunnel or increases the volume of its contents will predispose to CTS, and many medical associations have been …

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