[Conductive deafness without perforation of tympanic membrane with reference to cases of undetermined incudostapedial joint disorder].

In order to elucidate the pathophysiology of an undetermined conductive deafness without perforation of the tympanic membrane, comparative study was made in several factor with conductive deafness which has normal tympanic membrane and may be due to inflammation. Differences and similarities in the manner of ossicular damage were discussed in these conductive deafness. The morbidity rate of conductive deafness without perforation of the tympanic membrane which was undetermined cause, was found in wide age group 7 to 56 years of age. The site of damage was found at portion of the incudostapedial joint. The origin of etiology was estimated may take part in inflammatory process. We emphasized that such as undetermined conductive deafness may increase according to increase of otitis media with effusion.