Objective
To evaluate the sensitivity and specificity of each parameter including the distoproximal ratio(D/P ratio) in median nerve conduction.

Method
Median motor and sensory nerve conduction studies were performed in 48 patients(66 hands) with the clinically diagnosed carpal tunnel syndrome and 33 control(46 hands).

Sensory nerve conduction was measured from index finger both antidromically and orthodromically, and from middle finger orthodromically.

Orthodromic sensory nerve conduction velocity was measured in the median nerve between the middle finger and palm and between the palm and wrist. These figures were used to calculate the ratio of distal to proximal conduction.

Results
The sensitivity of each parameter was 47.0% to 74.2% with control mean⁑2SD as reference value. The sensitivity of distoproximal ratio was 74.2%.

The sensitivity of each parameter was 76.1% to 90.9% with the predictive value method. The highest diagnostic yield was obtained with the distoproximal ratio(90.9%).

Conclusion
Normal limits should be derived from acceptable statistical analysis. Segmental study of median sensory nerve conduction velocity with calculation of the distoproximal ratio is a sensitive parameter for the diagnosis of mild to moderate carpal tunnel syndrome.