Normalvärden och F-waves vid registrering på tibialis anterior vid undersökning av peroneus communis med elektroneurografi

Abstract

Electroneurography is used to examine a suspected entrapmentneuropathy in peroneus communis (PC), where an electric stimulus enables the evaluation of nerve conduction velocity, muscle response amplitude and latency. If registration from the extensor digitorum brevis (EDB) provides unreliable results, the registration can be made from tibialis anterior (TA). Currently there are no normal values available in our laboratory and no standard method regarding the registration on TA. The purpose of this study was therefore to retrieve normal values for this registration and to develop and establish a method, and also compare the different registration sites, to examine the side differences from the registrations on TA, and how the height affected the latency. It was also examined if so called F-waves could be recorded from TA, and if so, determine the response rate and latency. 22 participants between 23-59 years an 154-190 cm were examined. TA was examined with the active registration electrode on the site where the muscle was the largest and the reference electrode on the ankle. Stimulations were made on lateral poplitea fossa and 110 mm lower on distal caput fibula. EDB were examined according to established methods. Normal values for the registration on TA were 2,2-5,4 mV regarding amplitude, 55-73 m/s regarding nerve conduction velocity and 3,8-5,9 ms regarding latency. Side differences were 0-1,4 mV regarding amplitude, 0-8 m/s regarding nerve conduction velocity and 0-0,8 ms regarding latency. The calculated limits show that it only takes small side differences to have a clinical significance. The method gave equivalent results to previous studies. 23 % of the latency could be explained by height. The comparing of the nerve conduction velocity from the different registrations showed a significant statistical, but not necessarily clinical, difference, with the bias 5 m/s. F-waves were retrieved from all participants with a response rate of 94-100 %. 41 % of the F-wave latency could be explained by height.