Correlating Median Nerve Cross-sectional Area With Nerve Conduction Studies.

PURPOSE: To determine whether there is a correlation between the cross-sectional area (CSA) of the median nerve, as measured using ultrasound, and the distal motor and/or sensory latencies as measured on nerve conduction studies.

METHODS: Patients with clinical signs and symptoms of carpal tunnel syndrome were prospectively enrolled in this study. Subjects underwent ultrasound measurement of the CSA of the median nerve at the carpal tunnel inlet by a fellowship-trained hand surgeon, followed by nerve conduction studies (NCS) by a certified electrodiagnostic technician who was blinded to the results of the ultrasound examination. Pearson correlations were performed to compare CSA and NCS.

RESULTS: Pearson correlation was r = 0.57 between CSA and distal motor latency and r = 0.47 between CSA and distal sensory latency. Correlation was r = 0.81 between distal motor latency and distal sensory latency.

CONCLUSIONS: There is a correlation between CSA of the median nerve and NCS. Further research is necessary to determine which test correlates better with patient symptoms and function.

TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.