Department of Otolaryngology-Head and Neck Surgery, Nara Medical University, Kashihara City, Nara, Japan.
J Int Adv Otol. 2021 Mar;17(2):156-161. doi: 10.5152/JIAO.2021.8632.
It has been revealed that the pure-tone audiometry demonstrates large air-bone gaps at low pitches due to the presence of inner ear fistulae. When a third mobile window resulting from an inner ear fistula is present, in addition to the 2 normally present windows consisting of the oval window and the round window, a portion of the air-conducted waves escape from the scala vestibuli through the inner ear fistula. On the other hand, bone-conducted waves traveling to the scala vestibuli are reduced by an inner ear fistula; however, bone-conducted waves traveling to the scala tympani are not affected by an inner ear fistula. This results in a larger gap than usual in compliance between both perilymphatic spaces and leads to a decrease in the bone conduction threshold. This phenomenon, so-called the third mobile window effects, sometimes may lead otology/neuro-otology surgeons to misunderstand the reason why large air-bone gaps still exist after ossicular reconstruction in tympanoplasty. This review article gives good examples regarding the third mobile window effects in otology/neuro-otology diseases and surgeries.
现已发现，由于内耳瘘的存在，纯音测听在低频时表现出较大的气骨间隙。当由于内耳瘘而存在第三个活动窗时，除了由卵圆窗和圆窗组成的通常存在的两个窗口之外，一部分空气传导波通过内耳瘘从前庭阶逸出。另一方面，通过内耳瘘的骨导波传播到前庭阶的骨导波减少;然而，骨导波传播到鼓阶的骨导波不受内耳瘘的影响。这导致了两个外淋巴间隙之间的顺应性比通常更大的间隙，并导致骨导阈值降低。这种现象，所谓的第三个活动窗效应，有时可能导致耳科学/神经耳科学外科医生误解为什么在鼓室成形术中进行听小骨重建后仍然存在大的气骨间隙的原因。这篇综述文章很好地说明了耳科学/神经耳科学疾病和手术中的第三个活动窗效应。
