Examination
A number of clinical signs are useful for confirming the diagnosis of CTS.
On routine examination, finding weakness on thumb abduction is common.
Weakness of resisted thumb abduction, i.e. movement of the thumb at right angles to the palm, is helpful in establishing the diagnosis of CTS.
Hyperflexion of the wrist for 60 seconds may elicit paraesthesia in the median nerve distribution, i.e. Phalen sign. Studies show that sensitivity can range from 10% to 73% and specificity from 55% to 86%.
The loss of two-point discrimination in the median nerve distribution, or abductor pollicis brevis atrophy, has a high specificity (>90%) but low sensitivity (<25%).
Tapping the volar wrist over the median nerve, i.e. Tinel sign, may produce paraesthesia in the median distribution of the hand. In studies, the sensitivity ranges from 8% to 100% and specificity from 55% to 87%. This test can be made at the wrist or elbow.