[Electrophysiological studies in acute Guillain-Barré syndrome]

Based on a synopsis of the literature and our own investigations we discuss the electrophysiological changes in acute Guillain-Barré syndrome. These changes must be viewed in relation to the clinical course of the illness. The SPA evoked by distal stimulation decreases by 50% during the first week of illness, continues decreasing in the second and third weeks and then shows a tendency to normalization. In a similar way, the motor NCV reaches a minimum in the third week and then shows a slow increase again. The motor NCV findings return to normal earlier than SPA. At an early stage we find changes in F-wave and distal latency as well. In connection with the clinical picture, the incidence of changes pointing to a primary demyelinating polyneuropathy can be seen as an electrophysiological sign for the Guillain-Barré syndrome. The relevant criteria are discussed. There are various views concerning the validity of the electrophysiological findings in terms of prognosis of acute Guillain Barré syndrome. Since prognosis is dependent, at first, on the amount of the denervation, the decrease of SPA is of importance. To be able to give a prognosis it is necessary to examine large number of motor nerves electrophysiologically. However, it is very often not possible to make a reliable electrophysiological prognosis in the individual case. The pathophysiological basis for electrophysiological changes in demyelinating PNP's is discussed.