2005 Fiscal Year Final Research Report Summary
Study of electron microscopical structure and taste function of regenerated chorda tympani nerve after severance during middle ear surgery
| Project/Area Number |
15591802
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Otorhinolaryngology
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| Research Institution | University of Fukui (2004-2005)
福井医科大学 (2003) |
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Principal Investigator |
SAITO Takehisa University of Fukui, Faculty of Medical Sciences, Associate Professor, 医学部, 助教授 (10139769)
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| Co-Investigator(Kenkyū-buntansha) |
TSUZUKI Hideaki University of Fukui, University of Fukui Hospital, Lecturer, 医学部附属病院, 講師 (90236927)
NARITA Norihiko University of Fukui, Faculty of Medical Sciences, Assistant Professor, 医学部, 助手 (80345678)
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| Project Period (FY) |
2003 – 2005
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| Keywords | chorda tympani nerve / middle ear surgery / nerve reconstruction / nerve regeneration / electron microscopy / myelinated nerve fiber / electrogustometry / filter paper disk method |
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| Research Abstract |
1. Method of nerve repair and incidence of regenerated chorda tympani nerve
After the chorda tympani nerve was severed during middle ear surgery, the proximal and distal stumps were anastomosed without suture on the temporal muscle fascia. Even if a nerve gap defect was created, the proximal and distal cut ends were placed on the temporal muscle fascia almost in the original position without nerve graft. During the second stage surgery of middle ear cholesteatoma, regenerated nerve was detected in submucosal layer of the reconstructed eardrum. Incidence of regenerated chorda tympani nerve was 46% (33/71 cases).
2. Functional result using electrogustometry and filter-paper disk method after severance of the nerve
In 33 cases with regenerated chorda tympani nerve, 61% (20/33 cases) had taste function. In other 87 cases whose chorda tympani nerves were severed during middle ear surgery, 24% (21/87 cases) showed recovery of taste function in eather electrogutometry or filter-paper disk method
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3. Morphological study of fungiform papillae (distribution and size)
In cases in which regeneration of the chorda tympani nerve was detected during the second stage of the surgery and taste function recovered, distribution and size of the fungiform papillae were observed using digital microscopy and their morphology was recorded in memory card. Distribution of the fungiform papillae was divided into three groups. (1)There was no difference in distribution of papillae between both sides on the tongue. (2)There is a difference in distribution between both sides. (3)The fungiform papillae was completely degenerated on the severed side of the tongue. In 35 cases whose taste function recovered after severance of the nerve, 31% was included in group 1 and 69% was in group 2. On the other hand, in 87 cases in which taste function did not recover, 61% was included in group 2 and 39% was in group 3.
These results indicate that, after severance of the chorda tympani nerve, the chorda tympani nerve regenerate in the middle ear and these regenerated nerve fibers reach to fungiform papillae and re-obtained taste function. Less
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