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Delayed repair of the facial nerve and its negative impacts on nerve and muscle regeneration

Cleuber Rodrigo de Souza Bueno1,2,3, Daniela Vieira Buchaim3,4,5, Benedito Barraviera6,7,  Rui Seabra Ferreira Jr.6,7, Paulo Sérgio da Silva Santos8, Carlos Henrique Bertoni Reis1,4,9,  Marcelo Augusto Cini10, Milton Carlos Kuga11, Geraldo Marco Rosa Junior12, Rogerio Leone Buchaim1,5* [ + show more ]

J Venom Anim Toxins incl Trop Dis, 2024, v 30: e20230093
Received: 24 November 2023 | Accepted: 12 April 2024 | Published online: 27 May 2024


Background: In this experimental protocol, we evaluated the immediate and delayed repair of the buccal branch of the facial nerve (BBFN) with heterologous fibrin biopolymer (HFB) as a coaptation medium and the use of photobiomodulation (PBM), performing functional and histomorphometric analysis of the BBFN and perioral muscles. Methods: Twenty-eight rats were divided into eight groups using the BBFN bilaterally (the left nerve was used for PBM), namely: G1 - control group, right BBFN (without injury); G2 - control group, left BBFN (without injury + PBM); G3 - Denervated right BBFN (neurotmesis); G4 - Denervated left BBFN (neurotmesis + PBM); G5 - Immediate repair of right BBFN (neurotmesis + HFB); G6 - Immediate repair of left BBFN (neurotmesis + HFB + PBM); G7 - Delayed repair of right BBFN (neurotmesis + HFB); G8 - Delayed repair of left BBFN (neurotmesis + HFB + PBM). Delayed repair occurred after two weeks of denervation. All animals were sacrificed after six weeks postoperatively. Results: In the parameters of the BBFN, we observed inferior results in the groups with delayed repair, in relation to the groups with immediate repair, with a significant difference (p < 0.05) in the diameter of the nerve fiber, the axon, and the thickness of the myelin sheath of the group with immediate repair with PBM compared to the other experimental groups. In measuring the muscle fiber area, groups G7 (826.4 ± 69.90) and G8 (836.7 ± 96.44) were similar to G5 (882.8 ± 70.51). In the functional analysis, the G7 (4.10 ± 0.07) and G8 (4.12 ± 0.08) groups presented normal parameters. Conclusion: We demonstrated that delayed repair of BBFN is possible with HFB, but with worse results compared to immediate repair, and that PBM has a positive influence on nerve regeneration results in immediate repair.


Keywords: Facial nerve; Nerve regeneration; Photobiomodulation; Fibrin sealant; Biopolymers.

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