LAUSR

Introduction Neurography is a well-established routine method for the quantitative study of nerve and muscle function. It is reproducible, non-invasive and can be performed by technicians. Over time new parameters have gone from experimental to routine area based on accumulated evidences. In addition, old parameters can now be explained in light of new knowledge. Here is a short summary of some of the details around routine techniques. Methods Standard surface electrodes are used for nerve stimulation and muscle recording. Results For motor conduction studies the surprising effect of the so-called reference electrode (E1) will be exemplified from studies of some hand and leg nerves. The knowledge of the signal generators is essential for the meaningful interpretation. The presentation will also include description and possible explanation of some abnormal signals (A-waves, extra discharges, CMAP satellites) seen in pathological conditions. For sensory conduction studies, the two recording electrodes give usually a similar contribution to the recorded signal which is generated by subtraction of two signals with a slight time differences. The practical importance of technical and biological factors such as interelectrode distance, signal shape (changed in pathology), and temperature will be discussed. Conclusion The Neurography signals may be more complex than usually realized. The underlying factors that determine or at least influence the signal shape must be understood and if possible standardized, for optimal interpretation of the relation between the signal and the biological generators.