1989 Fiscal Year Final Research Report Summary
Studies on sensorineural hearing loss using animal models
| Project/Area Number |
61440072
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Otorhinolaryngology
|
|---|
| Research Institution | University of Tokyo |
|---|
Principal Investigator |
NOMURA Yasuya Dept. of Otolaryngology, University of Tokyo Professor, 医学部, 教授 (30009948)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
SUGASAWA Masashi Dept. of Otolaryngology University of Tokyo Assistant, 医学部, 助手 (00179110)
KITAMURA Ken Dept. of Otolaryngology University of Tokyo Assistant Professor, 医学部, 講師 (90010470)
MIZUNO Masahiro Dept. of Otolaryngology University of Tokyo Associate Professor, 医学部, 助教授 (10049059)
KURATA Takeshi Dept. of Pathology National Institute of Health Director, 病理部, 部長 (50012779)
|
|---|
| Project Period (FY) |
1986 – 1989
|
| Keywords | animal model / perilymphatic fistula / vestibular function / Argon laser / otolithic organs / viral labyrinthis / electrophysiology / morphology |
|---|
| Research Abstract |
A small amount of perilymph was suctioned from the scala tympani through the round window. Morphological findings are identical to those found in animals in which artificial perilymph was injected into the subarachnoid space in order to produce experimental perilymphatic fistula. Perilymph suctioning through the round window can be used as an animal model of perilymphatic fistula (PLF).
Using the animal model, changes of compound action potentials (CAP), cochlear microphonics (CM) and summating potentials (SP) were recorded. Two animals out of 17 showed slight elevation of thresholds of CM and CAP without change of SP polarity. No significant morphological changes were found in these animals. Three animals developed reversal of SP polarity. One of them became deaf after showing a high amplitude SP. Bulging of Reissner's membrane was observed in this animal. SP disappeared in the remaining 12 animals. Various changes were observed in the temporal bone of animals, such as, rupture, collap
… More
se of Reissner's membrane and loss of hair cells. It is concluded that rapid withdrawal of perilymph can produce pathological changes in the membranous labyrinth.
Vestibular function was examined in animals with PLF (n=67). Five hours after suctioning of perilymph (4-10 mul) from the scala tympani through the round window, the suctioned animals showed spontaneous nystagmus to the normal side (89.5%). The nystagmus disappeared within 24 hours. One week after surgery, 24.6% of the animals showed positional nystagmus to the lesion side. There was no ice-water caloric response in the lesion side (73.9%).
Application of argon laser to the inner eat will play an important role in treatment of inner ear diseases. Argon laser was irradiated to the otolithic organs of guinea pigs and cynomolgus monkeys after stapedectmy. After irradiation the stapes was replaced. It was found that a single irradiaon of 1.5w x 0.5s to the maculae utriculi and sacculi resulted in complete disappearance of the otolith, sensory cells and nerve fibers. Hearing was preserved in these animals. Caloric response to ice-water showed that the lateral ampulla was normal.
We have developed a multi-purposes evoked response recording system using a personal computer. Parameters, such as, sound pressure of stimulus (0-155 dB), frequency, wave forms (tone burst, click), and sampling time (10 msec-1 sec) can be easily controlled. Using the system it is now possible to measure and record rapid to slow evoked responses.
Surgical closure of perilymphatic fistula is required. As a material for this purpose, we use an recently found material "Beschitin". The material dissolves itself within the vestibule without marked tissue reaction. Less
|
