Does the comparison of median-to-ulnar nerve sensory conduction add an additional value in electrodiagnosis of carpal tunnel syndrome?

BACKGROUND AND PURPOSE: Distal sensory onset latency (DSOL), conduction velocity (SCV) and nerve action potential (SNAP) amplitudes are used in electrodiagnosis of carpal tunnel syndrome (CTS) beside motor conduction data. The aim of our study is to search whether the comparison of median-to-ulnar nerve sensory conduction adds an additional diagnostic value in CTS or not.

METHODS

Median and ulnar nerve were stimulated on wrist, and SNAPs were recorded on second and fifth fingers, respectively. Best cut-off points for the searched parameters and their diagnostic efficiencies were determined. The cut off points were also stratified according to the age and gender, and their diagnostic efficiencies were calculated again.

RESULTS

The study includes 415 hands belong to 344 subjects. Best cut off points for median nerve DSOL and SCV were 2.7 msec and 49.0 m/sec with the diagnostic efficiencies of 87.7% and 88.7%, respectively. Best cut off points for DSOL difference and SCV difference were 0.62 msec and 4.0 m/sec, and efficiencies were 89.6% and 84.3%, respectively.

CONCLUSION

Determining the relative elongation of median nerve DSOL to the ulnar nerve one has a little additional value in electrodiagnosis of CTS, whereas any additional value is not obtained from SCV comparison.