Dynamic Eye Closure Restoration in Facial Palsy with Neurotized Platysma Muscle Graft in Rats

Background  One of the most devastating deficits of facial paralysis is eyelid dysfunction, which is controlled by the orbicularis oculi muscle (OOM), as it leads to loss of the protective mechanism of the eye. This study used a rat model to assess the functional outcomes of neurotized platysma muscle grafts (PMGs) for OOM replacement. Methods  Forty male Sprague-Dawley rats with iatrogenic right eyelid dysfunction were divided into five groups: one control group and four groups utilizing PMG with different sources of nerve innervation. Eyelid function recovery was assessed at 2, 4, 6, and 8 weeks. The PMGs were harvested for pathological examination at the end of the study. Results  All rats except those in the control group and one from the group using ipsilateral frontal and upper zygomatic frontal nerve branches directly neurotized to the PMG (nerve-to-muscle) recovered eyelid closure function within 8 weeks of the study period. The mean recovery time was 3.87 ± 1.28 weeks. A total of 87.5% of rats that had the contralateral zygomatic branch as the donor nerve regained the consensual corneal reflex (p -value < 0.001). Conclusion  Replacement of neurotized PMG for OOM function is successful in a rat model. Using the upper zygomatic branch as the donor nerve, it was possible to restore the consensual corneal reflex. This method shows promise for further human studies.