2005 Fiscal Year Final Research Report Summary
Induction of hyperexcitability in the rat facial nucleus-to analyze the mechanism of the hemifacial spasm-
| Project/Area Number |
16591430
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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 |
Cerebral neurosurgery
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| Research Institution | Chiba University |
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Principal Investigator |
YAMAKAMI Iwao Chiba University, graduate school of medicine, Associate Professor, 大学院・医学研究院, 助教授 (90241968)
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| Co-Investigator(Kenkyū-buntansha) |
MINE Seiichiro Chiba University, School of medicine, Assistant Professor, 医学部附属病院, 講師 (70190709)
MURAI Hisayuki Chiba University, University Hospital, Research Associate, 医学部附属病院, 助手 (80241967)
KOBAYASI Eiichi Chiba University, University Hospital, Research Associate, 医学部附属病院, 助手 (10225493)
ITO Seiichiro Chiba University, graduate school of medicine, Research Associate, 大学院・医学研究院, 助手 (50376373)
SHIMOYAMA Ichiro Chiba University, Research Center for Frontier Medical Engineering, Professor, 教授 (60115483)
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| Project Period (FY) |
2004 – 2005
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| Keywords | hemifacial spasm / hyperexcitability of facial nucleus / animal model / microvascular decompression / lateral spread |
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| Research Abstract |
There are two hypotheses for the pathogenesis of hemifacial spasm (HFS) : abnormal cross-transmission between the facial nerve fibers at a site of vascular compression, and hyperactivity of the facial nucleus. To further elucidate the mechanism of HFS, we established an animal model. We applied chronic electrical stimulation (CES) to the facial nucleus in rats, and clarified functional and morphological changes in the nucleus. Under anesthesia, a novel intracranial electrode was stereotactically implanted in the facial nucleus of six rats. CES of the facial nucleus via the implanted electrode was applied for 5 minutes daily for three weeks (CES animals). Facial electromyograms (EMGs) were recorded at rest and during electrical stimulation to study the excitability of the facial nucleus at 1,2,and 4 weeks after initiating CES. As control animals, six rats were implanted with intracranial electrodes, but did not undergo CES. Electrophysiological studies of the control animals were performed using the same protocol as in the CES animals. Spontaneous abnormal movement of the facial muscle mimicking HFS did not occur. Four weeks after starting CES, one of the six CES animals developed an abnormal EMG response with a latency of 10 ms. No control animals developed such a response. CES of the facial nucleus can produce an abnormal EMG response very similar to the abnormal muscle response (AMR) characteristic of HFS patients. Kindling-like hyperactivity of the facial nucleus induced by CES is the cause of the AMR, suggesting a pathogenesis of HFS.
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