The origin of spontaneous discharges in acquired neuromyotonia. A Macro EMG study.
OBJECTIVE
To study the generator sites of spontaneous discharges in patients with immune-mediated neuromyotonia.


METHODS
Macro EMGs triggered by both spontaneously and voluntarily activated single action potentials were recorded and the mean peak-to-peak amplitude and area of the macro motor unit potentials were compared in two patients with typical acquired neuromyotonia having positive antibodies against voltage-gated potassium channels.


RESULTS
Mean peak-to-peak amplitude and area of Macro EMG motor unit potentials (macro MUPs) triggered by spontaneous discharges were significantly smaller than those triggered by voluntary activation in both patients. However, a few macro MUPs triggered by spontaneous discharges resembled those triggered by voluntary activation.


CONCLUSIONS
Spontaneous discharges in two patients with immune-mediated neuromyotonia seem to be mostly generated at sites distal to the terminal axon branching points.


CONCLUSIONS
This finding may provide a new insight in the understanding of spontaneous discharges in immune-mediated neuromyotonia.
Arimura
Kimiyoshi
K
Department of Neurology and Geriatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Sakuragaoka, 8-35-1 Kagoshima, Japan. ari@m2.kufm.kagoshima-u.ac.jp
Arimura
Yumiko
Y
Ng
Arlene
A
Uehara
Akiko
A
Nakae
Megumi
M
Osame
Mitsuhiro
M
Stålberg
Erik
E
D000200:Action Potentials; D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D020386:Isaacs Syndrome / Q000276:immunology / Q000503:physiopathology*; D008875:Middle Aged; D009068:Movement; D018482:Muscle, Skeletal / Q000502:physiology