Technical artifact simulating "motor axonopathy".
We describe 3 patients, referred for other problems, whose nerve conduction studies revealed low compound motor amplitudes, normal motor conduction velocities and normal sensory nerve studies, consistent with a motor axonopathy. EMG was normal. The unexpected nature of these findings precipitated a search for technical artifact. A partial transection of the active electrode was found. After replacement, repetition of the motor studies was normal. Our explanation was of a normal "reference" signal being subtracted from a present but diminished "active" signal.
Gilchrist
J M
JM
Department of Neurology, Rhode Island Hospital, Brown University, Providence.
Dosremedios
E
E
Johnson
G
G
Tornabene
J
J
D016477:Artifacts; D001369:Axons / Q000502:physiology*; D004566:Electrodes; D004576:Electromyography / Q000295:instrumentation*; D004868:Equipment Failure; D005260:Female; D006801:Humans; D008297:Male; D009431:Neural Conduction / Q000502:physiology; D009468:Neuromuscular Diseases / Q000175:diagnosis*; D010525:Peripheral Nerves / Q000502:physiology