[Repetitive discharges of proximal origin in a patient with carcinomatous sensory neuropathy].

Repetitive discharges of a motor unit potential were observed during ulnar nerve conduction studies in a patient with pathologically verified carcinomatous sensory neuropathy. The repetitive discharges in this patient had a latency similar to that of the F-wave latency. The first discharge was followed by discharges identical in configuration every 3 to 4 msec. These discharges responded to all of the suprathreshold stimuli, had a constant configuration, and exhibited jitter in their latency. When paired stimuli were applied, the second stimulus collided with the first discharge, leaving the afterdischarges behind at the previous position. Based on these electromyographic findings, the origin of these repetitive discharges is believed to have been the proximal part of a motor axon or a neighboring demyelinating lesion, since degenerative changes have been demonstrated in ventral roots as well as dorsal root ganglia in this disease.