アブミ骨筋反射のon-off反応についての臨床的観察

"ON-OFF" EFFECT IN STAPEDIAL REFLEX

　I．はじめに

　インピーダンスオージオメトリーは今日かなり普及し耳科臨床において診断あるいは治療効果の判定などに広く用いられている。このうちアブミ骨筋反射は，神経，筋，耳小骨など多くの組織が関与するために臨床的応用も広く，価値が高い。

　アブミ骨筋反射を測定し，compliance changemeterの針のふれを観察，あるいはこれを記録すると，時に通常と異なった動き，あるいは波形が観察される。その一つに逆むきのふれ（逆むきのアブミ骨筋反射）があり，その臨床的意義については一部すでに報告した^1）。今回は逆むきの波形が音刺激の開始時，終了時のみに起こるon-off反応あるいはdouble negative deflectionについて臨床的観察を行ったので報告する（第1図）。

　An on-off effect or double negative deflection was observed in 27 cases out of 1,200, who visited our clinic and were performed impedance audiometry. The effect was found in patients with otosclerosis (43%), sensorineural hearing loss (20%) and in normal hearing person (27%). Four patients with the effect, who were stapedectomized, indicated that duration of the symptom and degree of the stapes fixation were not related to the on-off effect. However, there was a case of mild conductive hearing loss who showed relatively rapid deterioration of the hearing. Therefore, the effect might be indicative of progress of hearing loss, even in normal hearing person. Another patient was presented to show that similar but abnormal recordings resulted from different pathological changes.