Brain-derived neurotrophic factor-enriched collagen tubule as a substitute for autologous nerve grafts

Background: Autologous nerve interposition grafts are frequently harvested by head and neck surgeons. The sacrifice of these donor nerves guarantees some degree of morbidity, including sensory loss, additional incision sites with associated potential complications, and prolonged operative time. An alternative to autologous nerve grafting is, therefore, desirable. Objective: To determine if a collagen tubule (CT) filled with either a plain collagen gel or a brain-derived neurotrophic factor (BDNF)-enriched collagen gel could be used to achieve functional and histologic outcomes equivalent to an autologous nerve graft in bridging a 15-mm nerve gap in the rabbit facial nerve. Design: A prospective, randomized, blinded animal study with a control group. Methods: Thirty rabbit facial nerves were resected (15-mm segments) to create nerve gaps. The gaps were bridged using 1 of 3 methods, assigned randomly: a reversed facial nerve (control), a collagen gel-filled CT, or a BDNF-enriched collagen gel-filled CT. The animals were evaluated after 6 weeks in a blinded fashion for functional nerve recovery, axon count, and axonal diameter. Results: There were no significant differences between the autologous nerve graft group, the collagen gel-filled CT group, or the BDNF-enriched collagen gel-filled CT group (n = 10 for each group) for functional nerve recovery (P = .94). The mean axon count and the mean axonal diameter were highest in the BDNF-enriched collagen gel-filled CT group, but these differences failed to reach statistical significance (P = .18 and .96, respectively). Conclusions: Collagen tubules filled with BDNF-enriched collagen gel appear to be at least as good as autologous nerve grafts for bridging short facial nerve gaps. Larger experimental studies are warranted to determine if clinical trials are justified.