AN ANALYSIS OF EVOKED ELECTROMYOGRAM FROM ORBICULARIS OCULI IN PATIENTS WITH MYASTHENIA GRAVIS |
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Authors: | Kenzo MATSUOKA Takashi KATSUDA |
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Institution: | The First Department of Surgery, Osaka University Medical School, Osaka |
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Abstract: | Evoked electromyograms of the orbicularis oculi muscle with repeated stimulation given at frequencies of 5, 10, 20, 50 and 100 c/s were examined in myasthenia gravis; and the following results were obtained. 1. In the normal subject, the amplitude of M-waves showed almost no change by stimulation at frequencies of 5 and 10 c/s, and a mild gradual increase by stimulation at a frequency of 20 c/s. On stimulation with 50 and 100 c/s, the amplitude of M-waves showed a marked gradual increase and maintained nearly the peak value after a maximum had been reached. 2. In a total of 23 patients with myasthenia gravis, the amplitude of M-waves showed several specific changes against the stimulation frequencies employed. The patterns of the amplitude of M-waves appearing with each frequency were classified into 3 types: Type I, which showed an initial gradual decrease in amplitude with all the stimulation frequencies employed, was observed in 13 patients (56.5%). Type II, which showed an initial gradual decrease at frequencies of 5 c/s and 10 c/s, but a gradual increase followed by gradual decrease at frequencies of 50 and 100 c/s, was observed in 8 patients (34.8%). Type III, which showed no obvious difference from the pattern of the normal curve with stimulation given at not more than 50 c/s but a gradual increase followed by gradual decrease at a frequency of 100c/s, was observed in 2 patients (8.7%). 3. No distinct differences were noted in other neuromuscular diseases taken as control, as compared with the normal. |
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