title: Propagated insertional activity: a model of positive sharp wave generation.
abstract: In this study we utilized a dual monopolar needle recording technique to assess propagated electromyographic insertional activity from the same single muscle fiber in order to characterize different categories of insertional activity. A total of six combinations of insertional activity were identified. Only two fundamental types of single muscle-fiber insertional discharge configurations were generated: biphasic initially-negative and monophasic positive. The propagated waveforms corresponding to these two insertional discharges were primarily triphasic initially-positive and, only rarely, monophasic positive. The monophasic positive insertional activity generated at the inserting electrode site is postulated to arise from a depolarization zone adjacent to a needle-induced peri-electrode membrane crush. The monophasic positive discharge was utilized as a model for positive sharp wave generation. It is postulated that the majority of positive sharp waves are initiated at the inserting electrode adjacent to a needle-induced zone of muscle membrane crush in contrast to the previous supposition that positive sharp waves are blocked fibrillation potentials.
authors.affiliation: Department of Rehabilitation Medicine, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA. dumitru@uthscsa.edu
authors.forename: Daniel
authors.initials: D
authors.lastname: Dumitru
authors.forename: Carlos T J
authors.initials: CT
authors.lastname: Martinez
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D004566:Electrodes; D004576:Electromyography / Q000379:methods*; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology