D155. Exploring the Efficacy of a Novel Platysma Muscle Flap in Rat Models for Advancing Facial Paralysis Reconstruction Research

PURPOSE: Reconstructing the orbicularis oculi muscle following facial reanimation constitutes a difficulty for many surgeons. Its delicate, thin muscle fibers can only be reconstructed with similar muscles, such as the platysma muscle. However, the currently described platysma flap is technically very challenging. Therefore, the aim of this study was to establish a novel platysma flap model in rats to investigate alternative methods to utilize this flap for facial reanimation. METHODS: This anatomic study designed a platysma flap supplied by the cervical branch of the facial nerve and its accommodating vessel. The location and diameter of the neuro-vascular bundle was documented thoroughly. The muscle flap and the nerve branch were harvested for histologic analysis. Multiple stainings were used to assess the muscle morphology and neuromuscular junctions. The cervical branch was epoxy embedded and stained with toluidine blue for axon count analysis. RESULTS: In 36 male Sprague Dawley rats, the platysma was carefully separated from the skin and a 1.5x1.5cm large square was excised, parallel to the muscle fiber direction. The middle of the flap was positioned at the angle of the mandible. The neuro-vascular pedicle, consisting of 2 (±1) cervical branches and 1 vessel (±0.6), was observed to course from posterior and enter the flap approximately in the middle of the flap. The neuro-vascular pedicle was located within the flap in all dissections. CONCLUSION: This novel, reproducible platysma flap model will not only open the doors for new approaches for orbicularis oculi muscle reconstruction but also for novel platysma flap applications.