1999 Fiscal Year Final Research Report Summary
The long-term morphological changes of the facial nucleus in the model rat with the electrophysiological sings of hemifacial spasm.
| Project/Area Number |
09671405
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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 | YAMAGATA UNIVERSITY |
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Principal Investigator |
KUROKI Akira Department of Neurosurgery School of Medicine, Yamagata University, Assistant Professor (Instructor), 医学部, 講師 (90225285)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Shinjiro Department of Neurosurgery School of Medicine, Yamagata University, Assistant Professor (Instructor), 医学部, 助教授 (60153805)
KAYAMA Takamasa Department of Neurosurgery School of Medicine, Yamagata University, Professor and Chairman, 医学部, 教授 (50142972)
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| Project Period (FY) |
1997 – 1999
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| Keywords | hemifacial spasm / facial nerve / facial nucleus / vascular compression / demyelination / abnormal muscle response |
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| Research Abstract |
The abnormal muscle response, elicited by electrical stimulation of one branch of the facial nerve and recorded from muscles innervated by another branch, has been used as an objective sign of hemifacial spasm. We have reported that this abnormal muscle response was recorded in the rat model with chronic nerve injury and vascular contact at the peripheral facial nerve.
In the patient with hemifacial spasm, the abnormal muscle response is reversible, as it disappears when the hemifacial spasm disappears after the microvascular decompression operation. As shown in the previous study, the chronic nerve injury produced with a chromic suture attached to the peripheral facial nerve was associated with a focal demyelination. It is our assumption that the facial nerve and the facial motonucleus of the hemifacial spasm model rats may show some histological changes, despite the fact that the abnormal muscle response in the model rats is reversible shown as in the human.
In the model rats in which we could record the abnormal muscle response, eight rats lived more than 9 months. We sacrificed the eight rats and investigated the long-term histological changes of the facial nerve and the facial motonucleus on the affected side. Myelin staining with Toluidine blue showed that a focal and partial demyelination occurred at the site where a chromic suture was chronically attached. We, however, failed to show any histological change in the facial motonucleus.
This histopathological change of the facial nerve may resemble the Obersteiner-Redlich zone that is known as the transitional area between the central and the peripheral myelin. Chronic vascular irritation at the site of a mild demyelination can cause hyperexcitability of the facial nucleus but it is unlikely that this reversible hyperexcitability can be associated with an irreversible morphological changes in the facial nucleus.
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