title: Comparative observation of protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure.
abstract: OBJECTIVE
  To explore the protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure (BUP).
  
  
  METHODS
  The hearing thresholds of the guinea pigs were assessed with auditory brainstem responses (ABR). The traumatic levels of tympanic membrane and ossicular chain were observed under stereo-microscope. The rate of outer hair cells (OHCs) loss was analyzed using a light microscope. The changes of guinea pigs protected with barrel and earplug were compared with those of the control group without any protection.
  
  
  RESULTS
  An important ABR threshold shift of the guinea pigs without any protection was detected from 8h to 14d after being exposed to BUP with a peak ranging from -64.5 kPa to -69.3 kPa ( P<0.01). The rate of perforation of tympanic membrane reached 87.5% and that of total OHCs loss was 19.46% +/- 5.38% at 14d after exposure. The guinea pigs protected with barrel and earplug had lower ABR threshold and total OHCs loss rate compared with the animals without any protection (P<0.01). All of the tympanic membrane and ossicular chain of the protected animals maintained their integrities. Meanwhile, the guinea pigs protected with the barrel had lower ABR threshold and total OHCs loss rate than those with earplug (P<0.01).
  
  
  CONCLUSIONS
  The earplug and barrel have protective effects against BUP-induced trauma on auditory organs of the guinea pigs and the protective effects of barrel are better than those of earplug.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Daping Hospital, Third Military Medical University, Chongqing 400042, China. dapinghearing@263.net
authors.forename: Chao-jun
authors.initials: CJ
authors.lastname: Li
authors.forename: Pei-fang
authors.initials: PF
authors.lastname: Zhu
authors.forename: Zhao-hua
authors.initials: ZH
authors.lastname: Liu
authors.forename: Zheng-guo
authors.initials: ZG
authors.lastname: Wang
authors.forename: Cheng
authors.initials: C
authors.lastname: Yang
authors.forename: Hai-bin
authors.initials: HB
authors.lastname: Chen
authors.forename: Xin
authors.initials: X
authors.lastname: Ning
authors.forename: Ji-hong
authors.initials: JH
authors.lastname: Zhou
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
mesh_terms: D000818:Animals; D001309:Auditory Threshold; D001753:Blast Injuries / Q000517:prevention & control*; D004430:Ear Protective Devices; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism*; D011312:Pressure; D014432:Tympanic Membrane / Q000293:injuries*; D018058:Tympanic Membrane Perforation / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*