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Make the Diagnosis: Carpal Tunnel Syndrome

Prior Probability

Among all adults, the prior probability of hand symptoms compatible with CTS is 7%. See Table 10-6 for the likelihood ratios for Tinel and Phalan signs.

Table 10-6Likelihood Ratios for Tinel and Phalen Signs

Population for Whom Carpal Tunnel Syndrome Should Be Considered

  • Patients with tingling or numbness in the hands or arms—always assess for median nerve involvement.

  • Special populations include those with occupational exposure of repetitive motion or pregnancy in the third trimester.

  • The rates of CTS might be slightly higher in those with diabetes mellitus, rheumatoid arthritis, or hypothyroidism. However, the data are not convincing, and routine screening for these diseases will infrequently lead to new diagnoses.

Detecting the Likelihood of Carpal Tunnel Syndrome

The examination should focus on the distribution of symptoms in a hand diagram, rather than provocative maneuvers to elicit symptoms.

Reference Standard Tests

The distribution of hand symptoms (from a hand diagram) plus abnormal nerve conduction studies is the reference standard for epidemiologic studies.

For clinical care, patients can have CTS despite a normal nerve conduction result. Data are inconclusive about whether treatment outcomes differ according to the nerve conduction results.

Original Article: Does This Patient Have Carpal Tunnel Syndrome?

Clinical Scenario

A 55-year-old woman has difficulty sleeping because of numbness and tingling in her right hand for 6 months. On a hand diagram, she uses a pencil to locate precisely her numbness and tingling over the dorsal and palmar aspects of all 5 fingers, sparing the palm. On inspection, the patient has no evidence of thenar atrophy, but thumb abduction is weak on the affected side. Sensory examination result using monofilaments and a vibrating tuning fork is normal. Tinel sign is positive and Phalen sign is negative. Which of this patient's symptoms and signs are useful and which are useless for accurately predicting the diagnosis of carpal tunnel syndrome (CTS)?

Why Is the Diagnosis Important?

Carpal tunnel syndrome is an important cause of hand pain and functional impairment, attributable to compression of the median nerve at the wrist (Figure 10-1). Patients are usually between 30 and 50 years old, with women affected 3 times as often as men.2, 3 About 0.5% of the general population reports being diagnosed with CTS.2 It is likely, however, that ...

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