中耳刀伝音器疾患の骨導聴力に関する研究

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The purpose of this study is to find correlations between the degree of pathologic change or impedance change of the conductive apparatus and hearing acuity of bone conduction. Three methods were adopted to estimate the degree of pathologic change or impedance change of the conductive apparatus;1.the pathologic change of the conductive apparatus was examined by surgical operation in some cases.2.Hearing acuity of air conduction was tested.3.Hearing acuity by an acoustic probe was tested.Air conduction loss shows the loss of transmission of air vibration to the inner ear, and the hearing acuity tested with the acoustic probe shows the transmission loss of vibration, that is, the impedance change in the conductive apparatus.Sixteen different frequencies from 250 c.p.s.to 6000 c.p.s.were used for the test of hearing acuity of bone conduction and the test of hearing acuity with the acoustic probe.The subjects of the study were 175 cases of conduction deafness including chronic otitis media with central perforation, chronic otitis media with marginal perforation, chronic serous otitis. media and otosclerosis.Following results were obtained.1.the pathologic change of the conductive apparatus was examined by surgical operation in some cases.2.Hearing acuity of air conduction was tested.3.Hearing acuity by an acoustic probe was tested.Air conduction loss shows the loss of transmission of air vibration to the inner ear, and the hearing acuity tested with the acoustic probe shows the transmission loss of vibration, that is, the impedance change in the conductive apparatus.Sixteen different frequencies from 250 c.p.s.to 6000 c.p.s.were used for the test of hearing acuity of bone conduction and the test of hearing acuity with the acoustic probe.The subjects of the study were 175 cases of conduction deafness including chronic otitis media with central perforation, chronic otitis media with marginal perforation, chronic serous otitis.media and otosclerosis.Following results were obtained.1.Two fundamental forms of hearing curve of bone conduction were obtained;the first form was the form of horizontal curve, the second form was the form which showed decreased threshold in low frequency range (below about 1000c.p.s.) and increased threshold in high frequency range (above about 1000c.p.s.), and a remarkable notch was found in the frequency range between 1200 c.p.s.and 3000c.p.s.in many cases of the second form.2.Each type of middle ear diseases did not show its peculiar form of hearing curve of bone-conduction.For example, so called Carharts notch was found not only in otosclerosis but com-monly in other type of middle ear diseases, and the hearing curves of bone conduction of chronic otitis media with disrupted ossicular chain were not distinguished from that of chronic otitis.media with normally connected chain.3.In many cases which shows low tone loss curves of air conduction.hearing curves of bone conduction of the first form (horizontal curve) were found.On the contrary, in many cases which shows high tone loss curves of air conduction, the hearing curves of bone conduction of second form (decreased threshold in low frequency range and increased threshold in high frequency range) were found.4.The case which showed low tone loss curve of hearing by the acoustic probe always.showed bone conduction curve of the first form.On the contrary, cases which posessed high tone loss curve of hearing by the acoustic probe usually showed bone conduction curve of the second form.5.From the results above mentioned, it was concluded that when stiffness is added to the conductive apparatus the bone the conduction curve shows the first form, and when mass isadded to the conductive apparatus the bone conduction curve shows the second form.
社団法人日本耳鼻咽喉科学会の論文

著者

武藤二郎
東京大学医学部耳鼻咽喉科学教室

中耳刀伝音器疾患の骨導聴力に関する研究

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