Document Detail

The effect of acoustic trauma on the tectorial membrane, stereocilia, and hearing sensitivity: possible mechanisms underlying damage, recovery, and protection.
MedLine Citation:
PMID:  3043645     Owner:  NLM     Status:  MEDLINE    
The aim of the present investigation was to determine: 1) the relationship between changes in auditory sensitivity and alterations in stereocilia micromechanics and tectorial membrane morphology after acoustic overstimulation; 2) the rate of growth of a threshold shift in stereocilia following in vitro overstimulation; and 3) if the damaging effects of noise trauma can be reduced by pre-exposure to a low level acoustic stimulus. After exposure to a 1.0 kHz pure tone signal at 105 dB SPL for 72 hours, the threshold of the auditory brainstem response was broadly elevated by approximately 40-50 dB; the inner hair cell stereocilia became less stiff; and morphological alterations were observed in the middle zone of the tectorial membrane. The location of both the stereocilia and tectorial membrane alterations corresponded to the region of the cochlea demonstrating a threshold shift. Following a recovery period from overstimulation, the auditory brainstem response showed some improvement yet a 25 dB threshold shift remained. At this time, swelling of the afferent dendrites beneath the inner hair cells was observed together with scattered outer hair cell loss. Also, the inner hair cell stereocilia regained their normal stiffness characteristics. The in vitro experiments demonstrated that overstimulation reduced the stiffness of the inner and outer hair cell stereocilia bundles. A threshold shift increased systematically with exposure duration and intensity. After 6 minutes of overstimulation, the threshold shift exhibited a plateau whose magnitude was dependent upon the exposure intensity. Stereocilia micromechanics were shown to be dependent on the metabolism of the hair cell. The pre-treatment to a low level acoustic stimulus (81 dB SPL) prior to exposure to a stimulus known to yield a permanent threshold shift resulted in a 20 dB reduction in the threshold shift relative to the group not pre-exposed as well as complete recovery from the threshold shift after 2 months.
B Canlon
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Scandinavian audiology. Supplementum     Volume:  27     ISSN:  0107-8593     ISO Abbreviation:  Scand Audiol Suppl     Publication Date:  1988  
Date Detail:
Created Date:  1988-09-13     Completed Date:  1988-09-13     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0325221     Medline TA:  Scand Audiol Suppl     Country:  SWEDEN    
Other Details:
Languages:  eng     Pagination:  1-45     Citation Subset:  IM    
Department of Physiology II, Karolinska Institute, Stockholm.
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MeSH Terms
Brain Stem / physiology,  physiopathology
Cochlea / pathology*
Ear, Middle / physiology
Evoked Potentials, Auditory
Hair Cells, Auditory / metabolism,  physiology,  ultrastructure*
Hearing Loss, Noise-Induced / pathology*,  physiopathology
Muscles / physiology
Sensory Thresholds
Tectorial Membrane / pathology*,  physiopathology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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