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November 1960

Mean Duration of Action Potentials in Extraocular MusclesAn Electromyographic Study

Author Affiliations

Jerry Lewis Fellow of the Muscular Dystrophy Associations of America (Dr. Gamstorp).; From the Department of Neurology and the Howe Laboratory of Ophthalmology, Harvard Medical School, the Neurology Service of the Massachusetts General Hospital, and the Massachusetts Eye and Ear Infirmary.

Arch Ophthalmol. 1960;64(5):744-750. doi:10.1001/archopht.1960.01840010746017

Electromyography of skeletal muscles has been in use for over 20 years and has proven to be a valuable diagnostic procedure. In analyzing the parameters of the electromyogram (EMG), Buchthal1 has pointed out the importance of the mean duration of the muscle action potential (the mean of the duration of 20 different action potentials), noting that the mean duration is influenced less by the electrode position within the muscle or by the patient's cooperation, than are the other parameters.

In 1953-1954, Björk and Kugelberg2 and Björk3 alone first applied the techniques of electromyography to the extraocular muscles. In 1955-1957, Breinin4-7 reported his experience with electromyography of extraocular muscles. Both Björk and Breinin stressed particularly the changes in amplitude and number of action potentials in normal and abnormal extraocular muscles, although Björk and Kugelberg2 incidentally mentioned changes in the duration. Although there have been several articles

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