title: The efficacy of N-acetylcysteine to protect the human cochlea from subclinical hearing loss caused by impulse noise: a controlled trial.
abstract: In military outdoor shooting training, with safety measures enforced, the risk of a permanent, noise-induced hearing loss is very small. But urban warfare training performed indoors, with reflections from walls, might increase the risk. A question is whether antioxidants can reduce the negative effects of noise on human hearing as it does on research animals. Hearing tests were performed on a control group of 23 military officers before and after a shooting session in a bunker-like room. The experiments were repeated on another group of 11 officers with peroral adminstration of N-acetyl-cysteine (NAC), directly after the shooting. The measurements performed were tone thresholds; transient-evoked otoacoustic emissions, with and without contralateral noise; and psycho-acoustical modulation transfer function (PMTF), thresholds for brief tones in modulated noise. Effects from shooting on hearing thresholds were small, but threshold behavior supports use of NAC treatment. On the PMTF, shooting without NAC gave strong effects. Those effects were like those from continuous noise, which means that strict safety measures should be enforced. The most striking finding was that the non-linearity of the cochlea, that was strongly reduced in the group without NAC, as manifested by the PMTF-results, was practically unchanged in the NAC-group throughout the study. NAC treatment directly after shooting in a bunkerlike room seems to give some protection of the cochlea.
authors: Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden. anncat.lindblad@ki.se
authors: Ann-Cathrine
authors: AC
authors: Lindblad
authors: Ulf
authors: U
authors: Rosenhall
authors: Ake
authors: A
authors: Olofsson
authors: Björn
authors: B
authors: Hagerman
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology / Q000627:therapeutic use*; D000328:Adult; D000704:Analysis of Variance; D001299:Audiometry; D001309:Auditory Threshold / Q000187:drug effects*; D016022:Case-Control Studies; D005260:Female; D016166:Free Radical Scavengers / Q000494:pharmacology / Q000627:therapeutic use; D006317:Hearing Loss, Noise-Induced / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008889:Military Personnel; D018384:Oxidative Stress / Q000187:drug effects; D011446:Prospective Studies; D017382:Reactive Oxygen Species / Q000009:adverse effects; D013548:Sweden; D061285:Vestibulocochlear Nerve Injuries / Q000150:complications / Q000209:etiology / Q000517:prevention & control*; D055815:Young Adult
chemical_list: D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D000111:Acetylcysteine