Yun Zhu1, Shanghui Zhou2, Wanlin Xu3, Limin Liu4, Hao Lu3, Wenjun Yang5. 1. Attending Physician, Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. 2. Associate Professor, Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. 3. Resident, Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. 4. Resident, Department of Oral Pathology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. 5. Professor, Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China. Electronic address: ywjdoctor@163.com.
Abstract
PURPOSE: High fractional dose radiotherapy (RT) produces better radiobiological results. However, a concern always exists regarding radiation-induced damage to normal tissues, in particular, the peripheral nerves. In the present study, we assessed the effects of postoperative RT on vascularized facial nerve grafts in a rabbit model. MATERIALS AND METHODS: Surgical defects were created bilaterally on the upper buccal branches of the facial nerve in rabbits. One side received a vascularized nerve graft (VNG), and the other side received a free nerve graft (FNG). RT was planned in 1 group at 1 month postoperatively. The dose was equivalent to 60 Gy for each side. Evaluation of the facial performance, electrophysiologic monitoring, histologic studies, toluidine blue staining, and scanning electron microcopy were performed at 3 months after RT. RESULTS: In the RT group, the pathological changes included surrounding tissue fibrosis, nerve cell shrinkage, Schwann cell injury, and demyelination. Compared with the control group, postoperative RT had no obvious effect on the regeneration and functional recovery of the facial nerves. The functional recovery rate of the VNG was faster than that of the FNG in the RT group. In addition, the difference in the nerve conduction velocity and amplitude was statistically significant between the 2 groups. CONCLUSIONS: Postoperative RT influenced the functional recovery of facial nerves to a certain degree. The use of VNGs could alleviate the adverse effects of RT on facial nerve regeneration.
PURPOSE: High fractional dose radiotherapy (RT) produces better radiobiological results. However, a concern always exists regarding radiation-induced damage to normal tissues, in particular, the peripheral nerves. In the present study, we assessed the effects of postoperative RT on vascularized facial nerve grafts in a rabbit model. MATERIALS AND METHODS: Surgical defects were created bilaterally on the upper buccal branches of the facial nerve in rabbits. One side received a vascularized nerve graft (VNG), and the other side received a free nerve graft (FNG). RT was planned in 1 group at 1 month postoperatively. The dose was equivalent to 60 Gy for each side. Evaluation of the facial performance, electrophysiologic monitoring, histologic studies, toluidine blue staining, and scanning electron microcopy were performed at 3 months after RT. RESULTS: In the RT group, the pathological changes included surrounding tissue fibrosis, nerve cell shrinkage, Schwann cell injury, and demyelination. Compared with the control group, postoperative RT had no obvious effect on the regeneration and functional recovery of the facial nerves. The functional recovery rate of the VNG was faster than that of the FNG in the RT group. In addition, the difference in the nerve conduction velocity and amplitude was statistically significant between the 2 groups. CONCLUSIONS: Postoperative RT influenced the functional recovery of facial nerves to a certain degree. The use of VNGs could alleviate the adverse effects of RT on facial nerve regeneration.