Median sensory distal latency as a practical screening parameter for carpal tunnel syndrome during routine nerve conduction studies.

Objective

Carpal tunnel syndrome (CTS) is typically evaluated using several nerve conduction parameters. However, in routine clinical practice, particularly in resource-limited settings, a single simple reliable screening parameter would be highly valuable. Materials and

Methods

We retrospectively reviewed 369 consecutive patients who underwent routine nerve conduction studies (NCS) followed by CTS-specific comparative tests. CTS was diagnosed electrophysiologically by using established comparative techniques as reference standards. The screening performance of the median sensory distal latency (SDL) and median motor distal latency (MDL) was assessed using receiver operating characteristic (ROC) curve analysis.

Results

Based on electrophysiological criteria, CTS was diagnosed in 254 patients (68.8%). SDL demonstrated better screening performance than MDL (AUC: 0.897 vs. 0.837). An SDL cutoff of 3.2 ms provided high sensitivity (0.842) with acceptable specificity (0.770). In contrast, MDL showed lower sensitivity (0.593) despite higher specificity (0.896).

Conclusion

Median SDL is a practical and effective first-line screening parameter that can be readily incorporated into routine NCS to guide further CTS-specific diagnostic testing. Specifically, SDL may be used as an initial screening step during routine NCS to determine whether additional CTS-specific comparative tests should be performed.