Objective: To establish an animal model of Bell palsy induced by type I herpes simplex virus (HSV-1) infection and to assess the role and site of HSV-1 in the pathogenesis of facial paralysis.
Methods: Fifty-three female Balb/c mice four-week-old weighted 16-18 g were studied. After scratching the surface of bilateral auricles with a 26-gauge needle, 25 microL HSV-1 with a titer of 6. 7 x 10(7) PFU/ml was inoculated into the right auricle, and the same volume of PBS was placed in the left. As a control, PBS was placed on the bilateral auricles of 4 mice. The HSV-1 DNA in bilateral facial nerve, bilateral brainstem, bilateral trigeminal carrier ganglion, bilateral brain, and blood at different stage was examined with polymerase chain reaction analysis.
Results: Thirty-seven animals (75.51%) appeared different degree facial paralysis among the 49 inoculated animals. Fourteen facial paralysis (37.84%) were on the right, 3 (8.11%) on the left, and 20 (54.05%) on the bilateral side. Six animals with facial palsy were recovered during 3-13 days, the average recovery time was 7.83 days.
Conclusions: The existence of HSV-1 in the brainstem and the cerebral cortex is significant for facial paralysis.