I n an earlier study, electrical activity in muscle was analyzed, using mathematical procedures and digital computer techniques to determine the effect of potential amplitude, wave shape, repetition rate and pulse duration on the harmonic spectrum (1). Special attention was directed toward the low frequency end of the spectrum because of the difficulty, in earlier studies, in extending the analysis in this direction. It was found that muscle potential amplitude and repetition rate could not be differentiated by size or shape of the spectrum. The principal characteristic of wave shape that could be detected was the base line duration of major amplitude muscle potential phase. Although previous studies had pointed in this direction (24), there were certain limitations in ease and rapidity of technique and in lower frequency limit of the analyzers, which led us to extend our studies, using procedures .which might be more suitable in the clinical situation than those we had used previously.In the previous study (l), the ulnar nerve was stimulated at the elbow, the muscle potentials obtained with a concentric needle electrode within the abductor digiti quinti muscle were photographed and the amplitudes of this potential were measured at 90 intervals. These amplitudes were then coded on IBM punch cards as input for a computer, and harmonic amplitudes of a Fourier series were calculated. This was a time consuming and costly procedure, though precise. The first goal of the present study was to determine whether analyses obtained by a commercially available wave analyzer were similar to those obtained with the procedure described above. If this were true, then studies would be extended to patients with proven myopathy or neuropathy. METHODSIn 10 subjects who had been studied previously (l), the frequency of the peak harmonic was calculated from data obtained with the digital computer. In 11 additional normal subjects, harmonic analyses were obtained utilizing a HewlettPackard wave analyzer (302A) with a flat frequency range from 20 cps to 50 kc.

No abstract

No abstract