[The effect of the lead electrodes on the conduction velocity of the sural nerve].

The result of nerve conduction velocity measuring depends upon all components of the measurement system. Earlier investigations showed that the nerve conduction velocity of the sural nerve depends also on technical attributes of recording electrodes. It was the objective of our study to investigate correlations between different recording electrodes and neurophysiological norm values as nerve conduction velocity and latency prolongation after paired stimulation of the sural nerve. Our investigations were carried out in twenty healthy volunteers aged 39 +/- 14 years. Stimulation of the sural nerve was performed at the lateral malleolus using always surface electrodes of the same type. Recording of nerve action potentials was done in each proband by four different types of electrodes. Surface electrodes consisted of tin, stainless steal and sintered silver/silver chloride, needle electrodes of stainless steel. The nerve conduction velocity using silver/silver chloride was 53.6 +/- 4.3 m/sec, using tin electrodes 53.1 +/- 3.9 m/s, using stainless steel 51.4 +/- 3.0 m/s and using needle electrodes 48,7 +/- 2.7 m/s. The Wilcoxon-test confirmed the differences of nerve conduction velocity between needle and silver/silver chloride and tin electrodes yielding p less than 0.05. Latency prolongation after paired stimulation of the sural nerve was independent from electrodes. In conclusion, our results indicate that electrodes take part in the system of standardization. Changing of recording or stimulation electrodes provoke the necessity of new standardization of norm values in clinical neurophysiology.