著者

南場 淳司 阿部 尚央 井上 卓 武田 育子 新川 秀一

出版者

日本聴覚医学会

雑誌

AUDIOLOGY JAPAN (ISSN:03038106)

巻号頁・発行日

vol.54, no.1, pp.70-77, 2011 (Released:2011-04-16)

参考文献数

12

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労災認定において詐聴, とくに誇大難聴が存在することは広く知られているところである。今回我々は2006年1月から2009年12月までの4年間に当科を受診し騒音性難聴の労災認定を希望した14症例を対象として, 従来施行してきた検査に加えて聴性定常反応検査 (ASSR) を行った。詐聴の診断はASSR閾値と純音聴力閾値を比較し, 純音聴力閾値がASSR閾値よりも高い場合を詐聴とした。結果は14症例中7例 (50%) を詐聴と診断し, その7例いずれも難聴の存在自体は明らかであり誇大難聴と考えられた。詐聴と診断した7例中6例は, 従来行ってきた検査からも詐聴と診断可能であり, ASSR検査結果と一致した。これまで騒音性難聴の意見書作成の際に, 詐聴の判断に苦慮するケースを少なからず経験してきたが, ASSR検査を行うことによりこれまでよりも正確に詐聴の診断ができる可能性が考えられた。

著者

南場 淳司 阿部 尚央 木谷 令 武田 育子 宇佐美 真一 新川 秀一

出版者

Japan Otological Society

雑誌

Otology Japan (ISSN:09172025)

巻号頁・発行日

vol.16, no.3, pp.183-188, 2006-07-25 (Released:2011-06-17)

参考文献数

20

被引用文献数

2

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An enlarged vestibular aqueduct, high frequency hearing loss, and fluctuating hearing loss are characteristics of enlarged vestibular aqueduct syndrome. Causes of fluctuating hearing loss include contusion or extreme movement of the head. In addition, mutations in the PDS gene have been reported as responsible for this condition.Case 1 began to have fluctuating hearing loss after a contusion in September 1999.After a decrease in hearing ability in the right ear in July 2001, recovery was not seen. However, two years and four months later, hearing recovery occurred suddenly.Case 2 began to have fluctuating hearing loss after a school athletic event in May 1998. After a decrease in hearing ability in the left ear in July 2003, immediate recovery was not seen but hearing was regained gradually over an eight-month period. Hearing loss was seen in the right ear in November 2004 and recovery occurred four months later.Fluctuating hearing is thought to be caused by the backward flow of low potassium fluid from the endolymphatic sac, following a sudden increase in pressure on the brain. The lowered potassium of the endolymphatic fluid contributes to a lowered endocochlear potential that causes the hearing impairment. On the other hand, it has been reported that in PDS gene knockout mouse, the expression of KCNJ 10, which is a potassium channel in the stria vascularis, is lacking and there is a markedly lowered voltage of endocochlear potential, suggesting that the inhibition of KCNJ10 is involved in hearing loss. Accordingly, the current two cases, in which long-term hearing impairment gradually or suddenly recovered, suggest that acute hearing impairment is not due to damage of the hair cells.