title: Effects of laserneedle stimulation in the external auditory meatus on brainstem and very early auditory evoked potentials in humans.
abstract: OBJECTIVE
  For the first time, brainstem auditory evoked potentials (BAEP) and very early auditory evoked potentials (EAEP) were investigated in 23 volunteers (mean age: 26.5 +/- 3.6 years) under resting conditions and during continuous and frequency modulated (2 Hz) laser stimulation in the external auditory meatus.
  
  
  METHODS
  Using a new ear adapter, the outer region of the auditory canal was stimulated with laser light (685 nm, 4 x 30-40 mW, duration: 10 minutes).
  
  
  RESULTS
  The EAEPs were significantly changed during continuous (p=0.019), as well as frequency modulated (p=0.014) laser stimulation compared with control measurements.
  
  
  CONCLUSIONS
  Physiologic alterations of inner ear mechanism such as extra-cerebral changes in conductance or stimulation-dependent depolarization processes in extra-cerebral regions of the auditory system could be possible explanations for the significant difference in measurement parameters.
authors.affiliation: Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, Medical University Graz, Austria. gerhard.litscher@meduni-graz.at
authors.forename: G
authors.initials: G
authors.lastname: Litscher
mesh_terms: D000328:Adult; D001300:Audiometry, Evoked Response / Q000379:methods; D001306:Auditory Pathways / Q000502:physiology*; D004307:Dose-Response Relationship, Radiation; D004424:Ear Canal / Q000294:innervation / Q000528:radiation effects*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000528:radiation effects*; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D011930:Reaction Time / Q000528:radiation effects