[Value of ratio of sensory nerves conductive velocity along palm-median finger/wrist-palm in diagnosing the carpal tunnel syndrome].

Objective: To Verify the value of the ratio of sensory nerves conductive velocity along palm-median finger /wrist-palm minus 1 for diagnosis of the mild-moderate carpal tunnel syndrome(CTS).
Methods: The different value between 1 and the ratio of sensory nerves conductive velocity along palm-median finger/wrist-palm was defined as index-CTS which was used to assess the severity of CTS.The index-CTS of 100 palms from healthy controls and 58 palms from mild-moderate CTS patients were calculated and compared.Multiple regression was used to identify the relative factors of index-CTS.The ROC curve was used to evaluate the sensitivity and specificity of index-CTS at different values.
Results: The value of index-CTS from healthy controls and patients both fitted Gaussian distribution.The mean value were -0.053±0.042 vs 0.055±0.074 in the controls and the patients respectively.The difference was statistically significant between the two groups by T-test(P<0.001). Multiple regression analysis showed that Tinel sign, Phalen sign, laterality, clinical grade, electrical grade were identifiable factors related to index-CTS.When index-CTS was over 0.001 and Ⅳ-DL over 0.395 ms , specificity of diagnosis by both can get 92%, but index-CTS showed more higher sensitivity(98.3% vs 89.7%).
Conclusions: Rising index-CTS could be the most significant electrophysiological feature in CTS.It can be used as a sensitive marker to assess the extent of conduction block of median nerve in carpal tunnel.