A collagen-coated PGA conduit for interpositional-jump graft with end-to-side neurorrhaphy for treating facial nerve paralysis in rat

Purpose: This study investigated the potential of collagen-coated polyglycolic acid (PGA) tube with interpositional jump graft (IPJG) in rat. Materials and Methods: A total of 16 Lewis rats were used in this study. Facial nerve paralysis was created by ligating facial nerve trunk with a ligature clip. The rats were divided into 3 groups. Nerve conduit group (n = 6) were treated by IPJG with collagen-coated PGA tubes between the facial nerve trunks and the hypoglossal nerves. Autograft group (n = 6) were treated by IPJG with the greater auricular nerves. As the control group (n = 4), non-treated-model rats with facial nerve paralysis were used. The number of myelinated fibers, fiber diameter, axon diameter, myelin thickness, and g-ratio, were analyzed histologically at 13 weeks after surgery. Compound muscle action potential (CMAP) and retrograde tracing were measured. Result: Although the number of myelinated fibers in autograft group (1957 ± 775) had significantly higher than that of nerve conduit group (90 ± 41, P <.05), the nerve conduit group showed the regeneration of myelinated nerve axons. CMAP amplitude values of the autograft (4706 ± 1154 µV) and the nerve conduit groups (4119 ± 1397 µV) were significantly higher than that of the control group (915 ± 789 µV, P <.05). Retrograde tracing confirmed the double innervation of mimetic muscles by the facial and hypoglossal nucleus in both groups. Conclusion: This study showed histologically and physiologically the superior effectiveness of performing IPJG with a collagen-coated PGA conduit in a rat model.