title: Ephaptic transmission from type ii afferents to static γ and β efferents causes complex repetitive discharge: An hypothesis.
abstract: BACKGROUND
  Complex repetitive discharges (CRDs) are thought to result from depolarization of a single denervated muscle fiber, followed by ephaptic spread to adjacent fibers. This leads to cyclic spread of the depolarization to produce a recurrent discharge. Another explanation is suggested.
  
  
  METHODS
  CRDs were recorded with single and multiple electromyographic needles longitudinal to muscle fibers in 39 neuropathy patients.
  
  
  RESULTS
  The mean frequency of CRDs was 26 Hz, mean number of negative spikes was 5.4, and blocking of spikes occurred in 53% of CRDs. In multi-needle recordings most CRDs were local, but propagation of the discharge was sometimes observed.
  
  
  CONCLUSIONS
  The prevailing hypothesis of CRDs cannot explain local CRDs. Type II afferents of bag2 and chain fibers branch widely in the juxtaequatorial region of muscle spindles where they may intermingle with motor terminals. Ephaptic transmission from type II afferents to static γ and β efferents may cause CRDs and fix the CRD frequency.
authors.affiliation: Department of Clinical Neurophysiology, University Hospital of Helsinki, Helsinki, Finland.
authors.forename: Juhani V
authors.initials: JV
authors.lastname: Partanen
mesh_terms: D000368:Aged; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009470:Muscle Spindles / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology*; D009476:Neurons, Efferent / Q000502:physiology*; D011999:Recruitment, Neurophysiological / Q000502:physiology*
keywords: complex repetitive discharge; electromyography; fusimotor; muscle spindle; type II afferent