Edrophonium-induced macrosaccadic oscillations in myasthenia gravis.
In a myasthenia gravis patient with profound ophthalmoplegia who was given edrophonium during forward fixation or horizontal/vertical saccades, horizontal macrosaccadic oscillations occurred that were conjugate, 2 to 3 Hz, and of peak-to-peak amplitude up to 50 degrees. The intersaccadic interval averaged 129.5 msec as measured by electro-oculography. Eye closure or the use of Frenzel goggles markedly reduced the amplitude and frequency of the macrosaccadic oscillations. This short latency is similar to that of a corrective saccade, and suggests that edrophonium induces macrosaccadic oscillations through a non-visually guided reflex saccade by temporarily unmasking the adaptively increased saccadic gain to overcome myasthenic ocular paresis.
Komiyama
A
A
Department of Neurology, Urafune Hospital of Yokohama City University, Yokohama, Japan.
Toda
H
H
Johkura
K
K
D004491:Edrophonium / Q000627:therapeutic use*; D004585:Electrooculography; D005260:Female; D006801:Humans; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000188:drug therapy* / Q000503:physiopathology; D012438:Saccades / Q000187:drug effects* / Q000502:physiology
D004491:Edrophonium