1993 Fiscal Year Final Research Report Summary
Mechanisms of vestibular symptons in perilymph fistula
| Project/Area Number |
04454436
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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 |
Ophthalmology
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| Research Institution | Showa University |
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Principal Investigator |
NOMURA Yasuya Showa University Medicine Professor, 医学部, 教授 (30009948)
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| Co-Investigator(Kenkyū-buntansha) |
SAKIKAWA Yasuhiko Showa University Medicine Assistant, 医学部, 助手 (00205791)
KOBAYASHI Hitome Showa University Medicine Assistant Professor, 医学部, 講師 (20234841)
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| Project Period (FY) |
1992 – 1993
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| Keywords | perilymph fistula / computer graphics / utricle / animal model / semicercular ducts / dizziness / membrana limitans / pathology |
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| Research Abstract |
Lack of human temporal bone studies on perilymph fistula gives un little information on pathophysiology of dizziness.
Two animal models of perilymph fistula are created in guinea pigs. Injection method is to inject artificial perilymph into the subarachnoid space until the round window ruptures. Suction method is to suction 4 mul of perilymph from the scala tympani of the basal turn through the round window. In celloidin specimens, these methods result in identical changes in the labyrinth. Those are collapse, hydrops and rupture. The utricle and semicircular ducts show only collapse.
There is the trabecular mesh around the membranous labyrinth in the pars superior. However, this is completely missing in specimens showing moderate and severe collapse. Strange enough is that the membrane limitans is preserved. There is no rupture in the collapsed utricular and ampullary wall, instead it is found in Reissner's membrane.
In these experiments, pressure of the perilymph rises suddenly and decreases immediately after the round window ruptures. This drastic change of perilymph pressure breaks Reissner's membrane and the endolymph is withdrawn. The endolymph in the pars superior movessimultaneously, resulting in collapse of the utricle and semicircular ducts.
Even 2 months after the experiment, sensory cells of the utricle and semicircular ducts are intact. Collapsed ampullary wall is lying on the crista. In the macula utriculi, the collapse occurs in the pars interna of the macula.
Collapsed utricular wall may sway when the perilymph moves. This produces shearing motion to the otolithic membrane and the senory cells. This may explain long-lasting dizziness inpatients with perilymph fistula.
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