[Serum demyelinating activity and Guillain-Barre syndrome: favorable effect of plasma exchange]

Abstract

The present study was designed to determine whether plasma exchange has a beneficial effect on the activity of the demyelinating factor present in the serum of patients with the Guillain-Barre syndrome. The demyelinating activity was assessed electrophysiologically after subperineurial injection of 20 to 30 microliters of serum into the rat sciatic nerves Serum was obtained from 26 patients from the French Cooperative Trial, among whom 12 had plasma exchange. Sera were drawn at hospital admission (DO) and at D15, D30 and D60. They consistently produced conduction block in a large proportion of motor axons, measured by the ratio of amplitudes of the motor action potential elicited by stimulation at both proximal and distal sites of injection. The serum activity diminished during the time course of the illness earlier in patients receiving plasma exchange and even more in patients with the less severe clinical score at the plateau phase. Serum from patients without motor sequelae after one year evolution did not produce conduction block prior to D30, as compared to sera from patients with sequelae which were still very active. This work add biological data to the positive results of plasma exchange in Guillain-Barre syndrome obtained by the North American and French Cooperative Trials.