[Can the efferent auditory system be explored via early evoked potentials? Preliminary results in normal hearing subjects and people with tinnitus].
The use of masking in brainstem auditory evoked potential technic remains one of the important issue regarding the evaluation of different auditory control systems. Brainstem auditory evoked response wave form latencies and amplitudes have been studied on 14 normal hearing subjects. On one hand the contralateral masking which theoretically stimulates the medial contralateral efferent bundle did not modify the responses. On the other hand, the ipsilateral masking stimulating the lateral bundle reduced the amplitude of wave I and lengthened the latency of interwave I to V. The same protocol has been applied to 21 tinnitus patients. In these subjects before masking, the waves amplitude was lower and inter wave I-V latency was lengthened. The ipsilateral did not modify the responses as in the normal population. Comparing brainstem responses obtained in masking and no masking condition offers the possibility of evaluating the lateral efferent system function but we can conclude that the contralateral masking is of no use studying the medial system and that dysfunctions of the lateral efferent system could be one mechanism responsible for tinnitus.
de Lavernhe-Lemaire
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MC
Service ORL, CHU Bretonneau, Tours, France.
Beutter
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P
D000328:Adult; D000368:Aged; D001306:Auditory Pathways / Q000502:physiology*; D004525:Efferent Pathways / Q000502:physiology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013997:Time Factors; D014012:Tinnitus / Q000503:physiopathology*
Le système efférent auditif peut-il être exploré par les potentiels évoqués précoces? Premiers resultats chez le normal et les porteurs d'acouphènes.