Development of a Novel Auditory Evoked Potential Measurement Method and Algorithm for Improving Hearing Prognosis in Vestibular Schwannomas

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K09565
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 56050:Otorhinolaryngology-related
• Research Institution: Keio University
• Principal Investigator: Oishi Naoki 慶應義塾大学, 医学部(信濃町), 准教授 (10348740)
• Co-Investigator(Kenkyū-buntansha): 細谷 誠 慶應義塾大学, 医学部(信濃町), 講師 (30645445) ; 和佐野 浩一郎 東海大学, 医学部, 准教授 (40528866) ; 高橋 英俊 慶應義塾大学, 理工学部(矢上), 准教授 (90625485)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 聴神経腫瘍 / 聴性脳幹反応 / 蝸電図 / 純音聴力検査 / 術中聴覚持続モニタリング / 蝸牛神経背側核活動電位 / 蝸牛内刺激電極 / 後迷路性難聴

Outline of Final Research Achievements

We analyzed approximately 400 cases of vestibular schwannomas and found that many cases of acute sensorineural hearing loss had U-shaped audiograms, especially in those under 40 years of age. In addition, we found that many elderly patients with vestibular schwannomas had a left-right difference in the high-frequency range.
We also demonstrated the possibility of hearing restoration from retro-cochlear hearing loss by utilizing a wave I of the auditory brainstem response during surgery. Furthermore, we achieved the world's highest hearing preservation surgery and established a new monitoring method using intracochlear stimulating electrodes. On the other hand, the usefulness of the cochlear electrogram was limited, and the superiority of the auditory brainstem response as auditory monitoring became clear.

Free Research Field

耳鼻咽喉科

Academic Significance and Societal Importance of the Research Achievements

聴神経腫瘍の聴力予後改善に向けて、約400例の聴神経腫瘍症例の純音聴力の特徴を解析し、特に急性感音難聴発症時の谷型聴力が有意に多いことを明らかにした。また、手術症例における聴力温存率向上に向けて以下の成果を上げた。
１）術中聴覚モニタリングの刺激音の最適化に取り組み、世界最高レベルの聴力温存率を達成した。２）ABR　I波を用いることで、後迷路性難聴における聴力回復の可能性を示した。３）新規術中蝸牛神経モニタリング法として、蝸牛内留置電極による蝸牛神経背側核活動電位測定を世界で初めて行い、最も信頼性の高い術中モニタリング法を確立させた。