1990 Fiscal Year Final Research Report Summary
Experimental Study on Hearing Impairment in Acoustic Neuromas
| Project/Area Number |
63480385
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Otorhinolaryngology
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| Research Institution | Keio University |
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Principal Investigator |
KANZAKI Jin Keio University School of Medicine, Professor, 医学部・耳鼻咽喉科, 教授 (00051441)
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| Co-Investigator(Kenkyū-buntansha) |
OGAWA Shigeo Keio University School of Medicine, Instructor, 医学部・耳鼻咽喉科, 助手 (10177131)
KUNIHIRO Takanobu Keio University School of Medicine, Instructor, 医学部・耳鼻咽喉科, 助手 (10170010)
OGAWA Kaoru Keio University School of Medicine, Instructor, 医学部・耳鼻咽喉科, 助手 (00169179)
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| Project Period (FY) |
1988 – 1990
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| Keywords | Acoustic Neuroma / Hearing Impairmet / Hypoxia / Cochlear Blood Flow / Steroid Hormone / Hypothermia |
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| Research Abstract |
The relationship between cochlear blood flow (CBF) and cochlear electrical activity was investigated to better understand cochlear circulatory insufficiency, which is considered to be a cause of hearing loss acoustic neuroma.
1. Experimental animal models for cochlear circulatory insufficiency
Experimental animal models for cochlear circulatory insufficiency were made by asphyxia, NO2 anoxia and obstruction of AICA.
Changes in systemic blood pressure (BP) during asphyxia and NO2 anoxia were clearly associated with changes in CBF. At the initial stage of asphyxia, however, CBF did not change in spite of the decrease in BP. These discrepancies appeared to be related to autoregulation of CBF. There was no difference in the change in compound action potential of the eighth nerve (AP) between asphyxia and NO2 anoxia.
Data from the experiment using AICA obstruction were insufficient to provide information on changes in AP as CBF decreased. However, the data indicated that the higher the CBF reduction rate, the higher the disappearing rate of AP.
2. Effects of steroid hormone and hypothermia on cochlear circulatory insufficiency
Although changes in CBF following systemic administration of steroid hormone were not clearly observed, the recovery time of N1 (AP) latency became shorter with systemic administration of steroid hormone. Similar results were obtained with hypothermia. Based on the analysis of these results, we concluded that the reversibility of the cochlear activity in cochlear circulatory insufficiency could be improved by the administration of steroid and hypothermia.
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