Stimulation of peripheral nerves using a novel magnetic coil

Magnetic nerve stimulation (MNS) using a novel figure-8 magnetic coil was c ompared with conventional electric nerve stimulation (ENS) in normal subjec ts and in patients with disorders of the peripheral nervous system. In cont rast to previously tested coils, the virtual cathode of the novel coil was independent of the geometrical or electric conditions of the stimulated tis sue. Maximal compound muscle action potentials (CMAPs) were elicited by MNS in all motor nerves tested. The slopes of the recruitment curves of ENS we re steeper than those of MNS, indicating a comparatively lower maximal stim ulation intensity and a higher intensity resolution of the magnetic stimula tor. In four patients with entrapment syndromes at the ulnar groove, motor conduction velocities and amplitudes were similar for MNS and ENS across th e affected nerve segment. However, in two patients with chronic inflammator y demyelinating polyneuropathy (CIDP), CMAPs were slightly smaller followin g MNS. This new technique is a promising step toward the ultimate goal of r eplacing ENS with MNS, (C) 1999 John Wiley & Sons, Inc.