Normative Values of Nerve Conduction Studies of the Ulnar and Median Nerves Measured in a Standardized Way
Abstract
The objective of the study was to set normative values of conduction parameters of the median and ulnar nerves on a sufficiently large group of healthy volunteers using standardized methodology. The examination of NU focused on conduction across the elbow region.
The differences in conduction parameters between males and females, dominant and non-dominant hands, right and left hands, and their dependence on age were also evaluated. Subjects and methods: A total of 227 healthy volunteers, mean age 39.4 years, were examined in five EMG laboratories in the Czech Republic.
NU: The amplitude of the compound motor action potential (CMAP) registered by a surface electrode from the abductor digiti minimi muscle (ADM) stimulated at the wrist, was 9.6 +/- 2.3 my; motor conduction velocity (MNCV) at the forearm was 60.4 +/- 5.2 mV; MNCV across the elbow 57.1 +/- 5.9 m/s. When registering from the first dorsal interosseus muscle (IDI) the amplitude of CMAP was 12.0 +/- 4.0 mV; MNCV was 59.7 +/- 4.7 m/s at the forearm, and 56.5 +/- 5.7 m/s across the elbow.
Mean difference between MNCV at the forearm and across the elbow was 3.3 +/- 6.6 m/s when registering from ADM and 3.2 +/- 6.4 m/s when registering from IDI, sensory nerve conduction velocity (SNCV) was 55.8 +/- 4.8 m/s. MN: The mean amplitude of CMAP was 10.0 +/- 3.0 mV; MNCV at the forearm was 57.1 +/- 4.6 m/s; the mean amplitude of the sensory nerve action potential for digit II was 25.7 +/- 12.5 mu V; SNCV was 55.8 +/- 4.7 m/s.
Conclusion: Owing to the standardized methodology and the large size of the examined group, the data from our study can be used as normative data for conduction studies of UN at the Guyon canal, the forearm, and across the elbow, as well as for the conduction studies of MN distally and at the forearm. Neither the differences in the measured parameters between males and females, dominant and non-dominant hands, and right and left hands, nor the decrease of MNCV with age were clinically significant.