Classic carpal tunnel syndrome (CTS) is a focal nerve entrapment of the median nerve at the carpal tunnel of the wrist resulting in a complex of clinical symptoms and signs in the distal distribution of the median nerve. The criteria in the NIOSH case definition for work-related CTS are the following:
1. Symptoms suggestive of CTS (paresthesias, hypoesthesia, or pain in distribution of the median nerve)
2. Objective findings such as positive Tinel's sign, Phalen's sign, or decreased sensation in the distribution of the median nerve or abnormal electrodiag-nostic testing
3. Evidence of work-relatedness (see Chapter 25)
Classic symptoms are paresthesias and pain with repetitive activity, nocturnal awakening relieved by "flicking" the wrist, and, in later stages, dropping objects, hypoesthesia in the median distribution, and thenar atrophy resulting in weakness of the abductor pollicis longus and opposition (46,47).
Tinel's and Phalen's signs and two-point discrimination lack sensitivity and specificity for the diagnosis of CTS. Electrodiagnostic testing is the gold standard but is 90% to 95% sensitive and may be false negative if performed before 4 to 6 weeks of when symptoms begin. Nonsteroidal antiinflammatory drugs (NSAIDs) are not considered to be effective, whereas nocturnal splinting, work-site modification, and steroid injection may be of satisfactory benefit. In long-standing cases with abnormal sensation and motor weakness, carpal tunnel release is the preferred initial treatment. Nonoccupational causes must be considered including metabolic conditions causing peripheral neuropathy (diabetes, hypothyroid conditions, vitamin B12 deficiency, chronic alcoholism), arthritis, cervical radiculopathy, and myofascial pain conditions (47).
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