[Sural nerve neurography using surface and needle electrodes in polyneuropathies. Comparative study].

It was the objective of our study to find a simple and reliable method for the electroneurographic examination of the sural nerve of patients suffering from polyneuropathy. As a first step, the normal values of persons not affected by this disease were taken by orthodromic technique and surface electrodes. The results were as follows: nerve conduction velocity: 59,44 m/s +/- 5,05; amplitude of the nerve action potential: 6,58 microV +/- 3,05; duration of the amplitude: 2,08 ms +/- 2,7; prolongation of latency after double stimulation: 3,37% +/- 0,77. Then potentials were stimulated by surface- and needle electrodes on the patients affected by polyneuropathy and recorded. Comparing the results gained by the different methods, we found that they correlated in a highly significant way, which means that all the methods are equally applicable. The stimulation and recording by surface electrodes, however, has apart from its reliability the additional advantage of being a simple, quick, and gentle method of examination. There is little objection to applying it repeatedly to the same patient. Further information about polyneuropathy can be obtained by the examination of the relative refractory period.