[Diagnostic tests in carpal tunnel syndrome]

Carpal tunnel syndrome (CTS) is a common condition affecting the median nerve. Clinical diagnosis often relies on provocative tests. However, the accuracy of these tests in distinguishing CTS from other nerve compression disorders remains unclear. Prior research has shown that passive movement tests like Phalen's test are frequently used, but their specificity is limited. This gap motivated a study to evaluate the diagnostic accuracy of both active and passive provocative tests in CTS patients and compare them with cervical nerve root entrapment cases. No prior work had resolved whether active movement tests could improve diagnostic precision. Understanding these differences is essential for refining diagnostic protocols and reducing misdiagnosis rates in clinical practice.

The study aimed to assess the sensitivity and specificity of various provocative tests for diagnosing CTS. It focused on comparing active and passive movement tests with established signs like Tinel’s and the flick sign. The researchers sought to determine whether active movement tests could offer better diagnostic value than passive ones. They also wanted to evaluate how these tests perform in differentiating CTS from cervical nerve root entrapment. The motivation stemmed from the need to improve diagnostic accuracy and reduce overlap with other nerve compression syndromes. The study aimed to provide evidence-based guidance for clinicians performing physical exams. It also aimed to identify tests with higher specificity for CTS to support differential diagnosis. The ultimate goal was to enhance clinical decision-making in hand and nerve disorders.

The study involved two groups of patients: one with CTS and another with cervical nerve root entrapment. Both groups underwent a battery of provocative tests, including active and passive movement tests, Tinel’s sign, and the flick sign. The researchers recorded the proportion of positive responses in each group. They also measured the average delay times for sensory disturbances during provocative movements. To assess specificity, they compared test results between the two groups. Subgroup analyses were conducted to rule out the influence of double crush syndrome. The data were analyzed using standard sensitivity and specificity calculations. The study design allowed for a direct comparison of diagnostic accuracy across different tests and conditions.

The most sensitive provocative tests for CTS were active and passive movement tests, with positivity rates between 72% and 84%. The average delay times for these tests ranged from 15.7 to 19.5 seconds. Tinel’s sign had a sensitivity of 64%, and the flick sign had a sensitivity of 69%. When tested in cervical nerve root entrapment patients, Phalen’s sign showed 74% sensitivity, and active thumb abduction had 68% sensitivity. Tinel’s sign had only 40% sensitivity in this group, indicating low specificity for CTS. The flick sign demonstrated 26% sensitivity in cervical nerve root entrapment, suggesting higher specificity for CTS. These findings imply that the flick sign may serve as a useful diagnostic criterion for CTS. The results were not influenced by double crush effects in subgroup analyses.

The study showed that active and passive provocative tests have high sensitivity for detecting CTS. However, their specificity is limited when compared to cervical nerve root entrapment cases. Tinel’s sign and Phalen’s test were found to be less specific for CTS, which may lead to diagnostic uncertainty. The flick sign emerged as a potentially specific indicator for CTS, with lower sensitivity in cervical nerve root entrapment patients. These findings suggest that the flick sign could be a valuable tool in differential diagnosis. The researchers propose that clinicians consider the flick sign alongside other tests to improve diagnostic accuracy. The results do not imply that any single test is essential for diagnosis. Instead, they suggest that a combination of tests may be more reliable in clinical practice.