Guillain-Barré Syndrome with Discharges Following Compound Muscle Action Potentials: A-waves, M Dispersion or After-Discharges?

In the very early days of Guillain-Barré syndrome (GBS), electrophysiological findings may be scarce but mostly required for the substantiation of nerve and/or nerve root pathology. Abnormal F-waves, absence of H reflexes, multiple A-waves and sural sparing are the best-known early findings of the disease. In this report, we present two cases with GBS in whom the early electrophysiology revealed discharges following the compound muscle action potentials. We propose that these discharges may be another early sign of GBS and may reflect early peripheral nerve demyelination and/or hyperexcitability.