[Sural neurography: comparative study in stimulation with surface and needle electrodes].

In 30 healthy volunteers aged 18-30 (ma 13, fem 17) the suralis nerve conduction velocity, the orthodromic NAP-duration and -amplitude were determined using both surface (SE) and needle (NE) stimulating electrodes (lateral malleolus); unipolar needle recording electrodes (sura), however, were used in all trials. Skin temperature was in between 31 and 34 degrees C (mean value 32, 14 degrees C); in each case nerve conduction velocity (NCV) was calculated up to 35 degrees C with 2 m/s per degree of deviation. Both the conduction velocity (SE: 56,78 +/- 6,1 m/s, NE: 53,27 +/- 4,8 m/s) and the NAP-amplitude (SE: 27,3 microV, NE: 12,21 microV) mean values were significantly higher when stimulating with surface electrodes (SE) than with needle electrodes (NE). The normal mean value of NAP-duration, however, was 1,3 ms using either technique. On the base of a linear regression line sensory nerve conduction velocity values with needle electrodes (NE-SNCV) can be transferred into sensory nerve conduction velocity values with surface electrodes (SE-SNCV) by the following formula: NE-SNCV = 26,57 + 0,47 . SE-SNCV.