Combined Amniotic Membrane and Dexamethasone Improve Regeneration Following Facial Nerve Transection in a Rat Model.

BACKGROUND

Facial nerve transection leads to significant functional and aesthetic deficits. Although microsurgical repair is the standard of care, complete functional recovery remains rare. Biological scaffolds and corticosteroids have been explored as adjuncts to enhance nerve regeneration. To evaluate the effects of human amniotic membrane (AM) wrapping and intraperitoneal dexamethasone, used alone or in combination, on facial nerve regeneration in a murine model.

METHODS

Twenty-eight male albino mice underwent right facial nerve transection followed by epineural repair and were randomized into 4 groups (n= 7 each): (1) control (repair only), (2) dexamethasone (1 mg/kg IP for 7 days), (3) AM wrapping, and (4) combination therapy (AM + dexamethasone). Functional recovery was assessed using compound muscle action potential (CMAP) recordings on postoperative day 21. Histological analysis included axon count, myelin density, axon diameter, and CD44/Ki-67 immunohistochemistry.

RESULTS

Group 4 (combination therapy) demonstrated the highest CMAP amplitude (5.5 ± 2.7 mV), axon count (median: 92.0), and myelin density (median: 50.5). Significant intergroup differences were observed in axon count (P < .001), myelin density (P < .001), and nuclear vacuole reduction (P=.04). Group 4 (combination therapy) demonstrated the highest CMAP amplitude (5.5 ± 2.7 mV); however, this increase did not reach statistical significance when compared with other groups (P=.299). Significant intergroup differences were observed in axon count (P < .001), myelin density (P < .001), and nuclear vacuole reduction (P=.04). Thus, while histopathological outcomes clearly favored Group 4, functional superiority should be interpreted with caution.

CONCLUSION

Combined use of AM and dexamethasone synergistically enhanced facial nerve regeneration in this model. This dual approach may serve as an effective adjunct to microsurgical repair in peripheral nerve injuries. Further studies are needed to confirm its translational potential.