Electrophysiological and histopathological evaluation of concentrated growth factor administration to facial nerve damage

Objective: The aim of this study is to investigate electrophysiologically and histopathologically the effect of concentrated growth factor(CGF) on nerve regeneration in a facial nerve crush injury model in rats, as well as to compare the effect of CGF with platelet-rich plasma(PRP) and dexamethasone treatment. Materials and Methods: 48 Wistar albino rats, which are 12 weeks old and average 300-350 gr, were used in this study. Rats were divided into sham group (n=8), control group (n=8), dexamethasone group (n=8), PRP group (n=8) and CGF group (n=8). Eight rats were used to obtain PRP and CGF. Except for the Sham group in all rats, the buccal branch of the facial nerve was traumatized with a mosquito clamp for 1 minute. Facial nerve stimulation thresholds were measured pre-traumatic, post-traumatic and at the end of the fourth week. At the end of the fourth week, the damaged area was excised and examined under the electron microscope. Diameter of the axon, thickness of the myelin sheath were measured and the g-ratio was calculated. Results: Comparing the post-treatment thresholds in all groups, the stimulation threshold was found to be significantly lower only in the CGF group than in the other groups (p<0.001). Axon diameter was found to be significantly thicker in the CGF group than in the control, dexamethasone and PRP groups (p<0.001). In terms of axon diameters, there was no significant difference between the control, dexamethasone and PRP groups. Regarding myelin sheath thickness, there was no significant difference between all groups. The g-ratio of the CGF group was found to be significantly higher than in the control (p=0.0047), dexamethasone (p=0.0011) and PRP groups (p=0.0024). There was no significant difference among the control, dexamethasone and PRP groups regarding g-ratio. Conclusion: This study is the first to examine the regeneration effect of CGF on the facial nerve histopathologically and electrophysiologically. In our study, it was observed that CGF had a significant effect on nerve regeneration. Keywords: concentrated growth factor, platelet-rich plasma, facial nerve, dexamethasone, nerve healing