所謂耳介腔骨導の伝音機構とその臨床的意義に就いて : 液導聴力検査の再検討

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It is absolutely necessary to know the condition of the ossicular chain preoperatively in tympanoplastic surgery.In addition to pure tone audiometry, patch test (covering test), Tsunodas liquid conduction test, Onchis bone conduction test on the pinna, and acoustic probe hearing test have been done for this purpose. Among these hearing tests, Tsunodas and Onchis methods are supposed to be the best way to know the condition of the ossicular chain and stapedial foot plate and can be done as a routine preoperative examination with simple equipments.On this paper, these two tests were reconsidere on the ground of experimental and clinical studies.The patient was placed in the lateral position with the examined ear upward and acoustic probe (10mm in diameter) was put on the cavitas conchae and another ear was masked with white noise.The following results and conclusions were obtained;1) The sound conduction route and its testing method based on the present experiment were termed “Meatus Conduction (M.C.) and its test”.2) M.C. may be different from ordinary bone conduction (B.C.) in quality. When the meatus was filled with water, threshold of M.C. and B.C. were decreased; on the other hand, with mercury of the same gravity of the water, threshold of M.C. was elevated in 15db, in contrast to the fact that threshold of B.C. was decreased.3) In this method, the vibratory sound is conducted from the bone conduction receiver to the cochlea via the bony wall of meatus and the ossicular chain in tympanic cavity, independent of condition of the tympanic membrane.4) The result that the threshold of M.C was variable according to the pathological changes of the ossicular chain was different from Tsunodas theory that the degree of ossicular chain disturbance was parallel to the difference between thresholdof M.C. and that of Liquid Conduction (L.C.).5) The degree of M.C. loss and that of L.C. loss depend on the function of the ossicular chain and that of stapedial foot plate in the perforated ears respectively. Therefore, the cases with M.C. loss and normal L.C. have sound conduction disturbances in the ossicular chain with intact stapedial foot plate, and if there are both M.C. and L.C. loss, some changes around the oval window may be found.6) The diagnostic standards obtained by analysis of 32 cases were available for differential diagnosis of conductive hearing loss.
社団法人日本耳鼻咽喉科学会の論文

所謂耳介腔骨導の伝音機構とその臨床的意義に就いて : 液導聴力検査の再検討

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