The effect of Methylprednısolone on facıal nerve paralysıs wıth dıfferent etıologıes

This study aims to investigate the effectiveness of methylprednisolone in facial nerve paralysis models induced by facial nerve transection, facial nerve compression, and inoculation of Herpes Simplex Virus (HSV) Type-1.The study was conducted on 30 female New Zealand rabbits weighing between 1200-3000 gr. The rabbits were randomly divided into six groups, five rabbits in each. Facial nerve injury in the form of transection was performed in Group 1a (Transection- Methylprednisolone Group) and 1b (Transection-Control Group). Facial nerve compression was performed in Group 2a (Compression- Methylprednisolone Group) and 2b (Compression-Control Group). Viral infection was used to perform facial paralysis in Group 3a (HSV Type 1- Methylprednisolone Group) and 3b (HSV Type 1-Control Group). The rabbits in the ?a? subgroups of all three groups were given a daily dose of 1 mg intramuscular methylprednisolone, while those in the ?b? subgroups received 1 cc of normal saline for three weeks. All rabbits were followed up for a period of 2 months. At the end of the follow-up period, the buccal branches of the facial nerves of rabbits were removed from the side where paralysis was performed. Semithin sections from the specimen were analyzed for perineural fibrosis, rate of increase in collagen fibers, miyelin degeneration, axonal degeneration, Schwann cell proliferation, and edema by using an optical microscope. Six areas were analyzed (on an objective magnification of 40X, 100X, 200X, and 1000X) in eight sections taken from each group. The mean values of the data pertaining to these areas were calculated, and the results were classified into three categories: Absent: (0), mild: +(1), moderate: ++(2), and severe: +++(3).In this experimental study, no significant difference was identified between the facial nerve transection experimental group that received methylprednisolone and the control group in perineural fibrosis, rate of increase in collagen fibers, miyelin degeneration, axonal degeneration, and edema. No significant difference was observed between the two groups in Schwann cell proliferation which plays an important role in nerve regeneration (p>0.05). In the compression group (Group 2), no difference was identified between the group that received methylprednisolone treatment and the control group in perineural fibrosis, rate of increase in collagen fibers, and Schwann cell proliferation; however, the control group had more axonal degeneration, miyelin degeneration, and edema than the experimental group that received methylprednisolone treatment. The difference between the compression groups were found to be statistically significant (p<0.05). In the group that was inoculated by HSV Type-1, no difference was observed between the group that received methylprednisolone and the control group in perineural fibrosis, axonal degeneration, miyelin degeneration, and Schwann cell proliferation. However, there was a significant difference between the two groups in edema to the advantage of the group that received methylprednisolone (p<0.05).The findings of this study investigating the effectiveness of methylprednisolone in facial nerve paralysis models suggest that methylprednisolone does not affect nerve regeneration in cases of facial paralysis associated with nerve transection; however, it was found to reduce neural edema in cases of facial paralysis associated with HSV Type-1 and to contribute to neural regeneration in cases of facial paralysis associated with nerve compression. The findings of this study could be further supported by future studies examining the changes generated by methylprednisolone treatment histopathologically and clinically included EMG.Keywords: Facial nerve paralysis, Methylprednisolone, Herpes Simplex Virus Type-1