title: Middle Latency Auditory Evoked Potential (MLAEP) in Workers with and without Tinnitus who are Exposed to Occupational Noise.
abstract: BACKGROUND
  Tinnitus is an important occupational health concern, but few studies have focused on the central auditory pathways of workers with a history of occupational noise exposure. Thus, we analyzed the central auditory pathways of workers with a history of occupational noise exposure who had normal hearing threshold, and compared middle latency auditory evoked potential in those with and without noise-induced tinnitus.
  
  
  METHODS
  Sixty individuals (30 with and 30 without tinnitus) underwent the following procedures: anamnesis, immittance measures, pure-tone air conduction thresholds at all frequencies between 0.25-8 kHz, and middle latency auditory evoked potentials.
  
  
  RESULTS
  Quantitative analysis of latencies and amplitudes of middle latency auditory evoked potential showed no significant differences between the groups with and without tinnitus. In the qualitative analysis, we found that both groups showed increased middle latency auditory evoked potential latencies. The study group had more alterations of the "both" type regarding the Na-Pa amplitude, while the control group had more "electrode effect" alterations, but these alterations were not significantly different when compared to controls.
  
  
  CONCLUSIONS
  Individuals with normal hearing with or without tinnitus who are exposed to occupational noise have altered middle latency auditory evoked potential, suggesting impairment of the auditory pathways in cortical and subcortical regions. Although differences did not reach significance, individuals with tinnitus seemed to have more abnormalities in components of the middle latency auditory evoked potential when compared to individuals without tinnitus, suggesting alterations in the generation and transmission of neuroelectrical impulses along the auditory pathway.
authors.affiliation: Department of Speech-Language Pathology and Audiology, University of Santa Maria, Santa Maria, Brazil.
authors.forename: Valdete Alves Valentins
authors.initials: VA
authors.lastname: dos Santos Filha
authors.affiliation: Department of Physical Therapy, Speech-Language Pathology and Audiology and Occupational Therapy, School of Medicine (FMUSP), University of São Paulo, São Paulo, Brazil.
authors.forename: Alessandra Giannella
authors.initials: AG
authors.lastname: Samelli
authors.affiliation: Department of Physical Therapy, Speech-Language Pathology and Audiology and Occupational Therapy, School of Medicine (FMUSP), University of São Paulo, São Paulo, Brazil.
authors.forename: Carla Gentile
authors.initials: CG
authors.lastname: Matas
mesh_terms: D000328:Adult; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000502:physiology; D005072:Evoked Potentials, Auditory; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D006309:Hearing / Q000502:physiology; D006320:Hearing Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D009623:Noise, Occupational; D009784:Occupational Diseases / Q000175:diagnosis*; D016273:Occupational Exposure; D014012:Tinnitus / Q000175:diagnosis / Q000503:physiopathology*