Correlation between two-point discrimination and median nerve sensory response

Static two-point discrimination (2PD) has been relied upon clinically to gauge the extent of median neuropathy in patients with carpal tunnel syndrome (CTS). Correlation with median nerve sensory conduction findings has not been well-established. We determined the median sensory nerve action potential parameters from the first and third digits of 83 hands referred primarily for suspected CTS. These results were compared to 2PD carried out in a standardized fashion by a group of hand surgeons. A lack of correlation was found in most electrodiagnostic parameters, with the exception of peak and onset latencies to the thumb; on further analysis, 2PD to the thumb was found to be useful if abnormal, but contributed nothing if negative. We conclude that static 2PD results may correlate with latency, but do not overall adequately predict the findings on sensory nerve conduction examination of the median nerve.