Electrodiagnostic Methods for Carpal Tunnel Syndrome Combined with Diabetic Polyneuropathy

ABSTRACT

OBJECTIVE: To find out the most useful method among three electrodiagnostic tests for carpal tunnel syndrome (CTS) in patients with diabetic peripheral polyneuropathy (PPN). METHOD: Eighty-three hands out of seventy-four patients who had diabetic PPN and tingling sensation in their hands were included in this study. They were divided into two groups Group A, PPN with CTS; Group B, PPN only. Fifty-four hands with CTS in patients without diabetes were included as a control group (Group C). Another forty normal hands were also included as a healthy control group (Group D). Clinical and electrophysiologic information was gathered from those subjects. Sensitivity, specificity and receiver operating characteristic (ROC) curves of the three electrodiagnostic tests, namely, the difference between the median nerve latency to the second lumbrical muscle and the ulnar nerve latency to the second interosseous muscle (L-I difference), ratio of distoproximal latency in median sensory nerve (MW ratio), and difference of distoproximal latency in median sensory nerve (MW difference) to diagnose clinical CTS were obtained. RESULTS: The specificity of L-I difference as a diagnostic test for CTS was highest (87.0%). The area of ROC curve of L-I difference was also highest (0.949) among three different electrodiagnostic tests of CTS with diabetic PPN. CONCLUSION: We suggest that L-I difference as the most useful test with highest specificity for the diagnosis of CTS in the patients with diabetic PPN.