Demyelination associated with HSV-1-induced facial paralysis

Hiroyuki Wakisaka, Naohito Hato, Nobumitsu Honda, Hirotaka Takahashi, Hisanobu Kisaki, Shingo Murakami, Kiyofumi Gyo, Katsumi Mominoki, Naoto Kobayashi, Seiji Matsuda

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


In 1995, we developed an animal model of transient homolateral facial nerve paralysis by inoculating Herpes simplex virus type 1 (HSV-1) into the auricle of mice. This study examined the mechanism of facial nerve paralysis in this model histopathologically. Using the immunofluorescence technique with anti-HSV-1 antibody, the time course of viral spread and the site of viral replication were investigated over the entire course of the facial nerve. Furthermore, viral replication and nerve degeneration at the site of viral replication were observed by electron microscopy. On the 7th day after inoculation, facial paralysis was observed in more than 60% of mice. Immunofluorescence study revealed HSV-1 in the geniculate ganglion, the descending root, and the facial nucleus at this stage. On the 9th day, the descending root in the sections stained with osmium looked pale, because prominent demyelination had occurred in this region; electron micrographs showed many degenerated oligodendrocytes and large naked axons. In contrast, the facial nucleus neurons showed no remarkable degeneration, despite HSV-1 particles in their cytoplasm. From these findings, we concluded that facial nerve paralysis in this model is caused mainly by facial nerve demyelination in the descending root.

Original languageEnglish
Pages (from-to)68-79
Number of pages12
JournalExperimental Neurology
Issue number1
Publication statusPublished - 2002
Externally publishedYes


  • Bell's palsy
  • Demyelination
  • Facial nerve
  • Herpes simplex virus type 1
  • Motor nerve dysfunction

ASJC Scopus subject areas

  • Neurology
  • Developmental Neuroscience


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