耳迷路外科の経験（第5報）—水平半規管開窓後の聽力に就て

　緒言

　現今の耳科において1つの重要な問題は，迷路に対する外科的侵襲による聽力改善の可能性の問題である．

　尤もかかる研究は外国では既に20年或はそれ以上も以前から行われていたことは周知の所であり，瑞典のHolmgren，仏蘭西のSourdilleの業績などは戦前夙にわが国にも知られていた．しかし日本に耳硬化症が少いということがまず第1の理由であると著者は常に考えていたがわれわれの先輩にも特にこの方面に研究を進めた人はなかつたようである．

TSUIKI performed fenestration operations on the hor-izontal canal of 4 patients who complained of hard of hearing. True fenstrations were instituted in some but, in others, the bony wall of the canal was thin-ned down to become almost transparent so that the membranous labyrinth could be seen as a dark linear structure. As results of this operation the patients were not onlyenabled to maintain hearing which the Patients properatively but showed some definite improvements. It is interesting to ponder whether that improvement is due to a new formation of acoustical island or to increase in area of the field for preceptibility of high tones.

In cases of inner ear deafness which was found among this number, the operation resulted in establish-ing a great improvement in the previously existing tinnitus, as in Case 3, or a complete relief, as in Care 4. The existence of close relationship between the amount of tinnitus and the amount of hearing in a reverse proportion must be recognized. In as much as tinnitus may be that of such a character as to be in agreement with speech frequecy. reception of speech would be greatly enhanced if such tinnitus were allayed or eliminated: improvement of hearing thus effcted may be more apparent than real. It appeared that the improvement seen in Case 4 to be falling under this form of abjustment but hearing in such cases may be further improved were they equ-iped with proper hearing aids.