Wide distribution of central myelin segment along the facial nerve might explain hemifacial spasm with distal nerve compression

Introduction Many researchers have assumed that neurovascular compression of the facial nerve at the site covered by central myelin sheath causes hemifacial spasm. However, some cases do not correspond to this hypothesis. The aim of this study was to clarify the myelin histology in the facial nerve....

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Published inClinical anatomy (New York, N.Y.) Vol. 34; no. 3; pp. 405 - 410
Main Authors Nomura, Kei, Ryu, Hiroshi, Ohno, Koji, Sato, Kohji
Format Journal Article
LanguageEnglish
Published Hoboken, USA John Wiley & Sons, Inc 01.04.2021
Wiley Subscription Services, Inc
Subjects
Brain stem
Cadavers
Compression
Face
Facial nerve
hemifacial spasm
Histology
microvascular decompression surgery
Myelin
myelin sheath
Nerves
oligodendroglia
Segments
Sheaths
myelin sheath
microvascular decompression surgery
facial nerve
hemifacial spasm
oligodendroglia
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Summary:Introduction Many researchers have assumed that neurovascular compression of the facial nerve at the site covered by central myelin sheath causes hemifacial spasm. However, some cases do not correspond to this hypothesis. The aim of this study was to clarify the myelin histology in the facial nerve. Materials and Methods Histological analyses were conducted on 134 facial nerves from 67 cadavers. Three dimensions were measured in these sections: the length from the upper border of the medullopontine sulcus to the boundary between the central and peripheral myelin sheath along the anterior side; the length from the detachment point of the brain stem to the boundary along the posterior side; and the length of the transitional zone (TZ), known as the Obersteiner–Redlich zone. Results Of the 134 facial nerves, 41 were available for study. The length of the central myelin segment ranged from 4.62 to 12.6 mm (mean 8.06 mm; median 7.98 mm) along the anterior side and from 0.00 to 4.58 mm (mean 1.68 mm; median 1.42 mm) along the posterior side of the facial nerve, and the length of the TZ ranged from 0.00 to 2.76 mm (mean 1.51 mm; median 1.42 mm). Conclusions In this study, the length of the central myelin segment in the facial nerve was found to be longer than that previously reported.
Bibliography:Previous presentations—Portions of this work were presented in an oral session at the 68th Annual Meeting of the Japan Neurosurgical Society, Tokyo, Japan, October 14, 2009.
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ISSN:0897-3806
1098-2353
DOI:10.1002/ca.23664