Heloisa Juliana Zabeu Rossi Costa

Experimental comparative study in rabbits of three different ways of cartilage graft fixation: suture, gelatin-resorcin-formaldehyde and butyl-2-cyanoacrylate

CONCLUSION The compound gelatin-resorcin-formaldehyde (GRF) was a better stabilizing material for cartilage grafts in rabbits than butyl-2-cyanoacrylate. GRF was also better than the suture when comparing fixation of cartilage to the periosteum and inflammatory reaction. OBJECTIVE Cartilage grafting is an interesting option for refinements on rhinoplasties. The objective of this study was to compare butyl-2-cyanoacrylate to GRF and suture to determine the efficacy of these methods in restraining grafted cartilage in rabbits. MATERIALS AND METHODS Fifteen male adult New Zealand rabbits underwent surgery with the aim of collecting six auricular cartilage grafts from each animal. Two of these grafts in each animal were glued together with butyl-2-cyanoacrylate, two were glued together with compound GRF, and two were sewn together with nylon suture. These sandwich grafts were then glued or sutured to the periosteum of the glabella. After 2, 6, and 12 weeks, groups of five animals were sacrificed and histological analysis for inflammation was performed. Cartilage graft migration, adhesion, and deformities of the grafts were also evaluated. RESULTS There was less migration of the cartilages glued with GRF than with cyanoacrylate and suture. GRF showed statistically less inflammatory reaction and angiogenesis than the other two methods. The three methods showed a tendency to decrease of fibrosis, inflammation, and angiogenesis as weeks passed. There was no detachment or deformity in the cartilage sandwiches sutured to the glabellas periostium. The majority of detached and deformed cartilages were those glued with cyanoacrylate. The number of detached cartilages was directly related to the number of deformed cartilages. The data were statistically significant (p<0.05).Conclusion: The compound gelatin-resorcin-formaldehyde (GRF) was a better stabilizing material for cartilage grafts in rabbits than butyl-2-cyanoacrylate. GRF was also better than the suture when comparing fixation of cartilage to the periosteum and inflammatory reaction. Objective: Cartilage grafting is an interesting option for refinements on rhinoplasties. The objective of this study was to compare butyl-2-cyanoacrylate to GRF and suture to determine the efficacy of these methods in restraining grafted cartilage in rabbits. Materials and methods: Fifteen male adult New Zealand rabbits underwent surgery with the aim of collecting six auricular cartilage grafts from each animal. Two of these grafts in each animal were glued together with butyl-2-cyanoacrylate, two were glued together with compound GRF, and two were sewn together with nylon suture. These sandwich grafts were then glued or sutured to the periosteum of the glabella. After 2, 6, and 12 weeks, groups of five animals were sacrificed and histological analysis for inflammation was performed. Cartilage graft migration, adhesion, and deformities of the grafts were also evaluated. Results: There was less migration of the cartilages glued with GRF than with cyanoacrylate and suture. GRF showed statistically less inflammatory reaction and angiogenesis than the other two methods. The three methods showed a tendency to decrease of fibrosis, inflammation, and angiogenesis as weeks passed. There was no detachment or deformity in the cartilage sandwiches sutured to the glabellas periostium. The majority of detached and deformed cartilages were those glued with cyanoacrylate. The number of detached cartilages was directly related to the number of deformed cartilages. The data were statistically significant (p<0.05).

Assessment of a Neurophysiological Model of the Mandibular Branch of the Facial Nerve in Rats by Electromyography

Objectives: Our objective was to develop an experimental model for the noninvasive and objective evaluation of facial nerve regeneration in rats using a motor nerve conduction test (electromyography). Methods: Twenty-two rats were submitted to neurophysiological evaluation using motor nerve conduction of the mandibular branch of the facial nerve to obtain the compound muscle action potentials (CMAPs). To record the CMAPs, we used two needle electrodes that were inserted into the lower lip muscle of the rat. A supramaximal electrical stimulus was applied, and the values of CMAP latency, amplitude, length, area, and stimulus intensity obtained from each side were compared by use of the Wilcoxon test. Results: There was no significant difference (all p > 0.05) in latency, amplitude, duration, area, or intensity of stimuli between the two sides. The amplitudes ranged between 1.61 and 8.30 mV, the latencies between 1.03 and 1.97 ms, and the stimulus intensities between 1.50 and 2.90 mA. Conclusions: This is a noninvasive, easy, and highly reproducible method that contributes to an improvement of the techniques previously described and may contribute to future studies of the degeneration and regeneration of the facial nerve.

Posttraumatic facial nerve regeneration in rabbits

UNLABELLED Posttraumatic facial paralysis is a frequent disease. This work studies posttraumatic regeneration of the facial nerve in rabbits. Functional and histological analysis compared injured and normal nerves on opposite sides. The left facial nerve trunk of twenty rabbits were subjected to compression lesion, and sacrificed after two (subgroup AL), four (BL) and six (CL) weeks. Comparison between groups was made by analysing total and partial densities of myelinated axons. STATISTICAL ANALYSIS Tukey Method (p<0.05). RESULTS There was partial functional recovery after two weeks, and complete recovery after five weeks. Qualitative analysis demonstrated a degenerative pattern in the AL group, with an increased tissue inflammatory process. Evident regeneration signs were observed in the BL group, and almost complete regeneration was seen in the CL group. Normal nerves (N) had an average TD of 15705.59 and average PD of 21800.75. The BL group had an average TD of 10818.55 and an average PD of 15340.56. The CL group had an average TD of 13920.36 and an average PD of 16589.15. The BL group had an average TD of N equal to 68.88%, and the CL group had an average TD of N equal to 88,63% (statistically significant). N showed a significant higher PD than injured nerves. However, this was not statistically different between BL and CL subgroups. Nerve DT was a more reliable method than PD in this study.

Estudo experimental comparativo entre o butil-2-cianoacrilato, a mistura gelatina-resorcina-formaldeído e sutura na estabilização de enxertos de cartilagem em coelhos

Os enxertos de cartilagem constituem-se em boa opcao tecnica para aprimoramento das rinoplastias. Procura-se um material para sua fixacao que seja de simples manuseio, e que provoque minima reacao tecidual. OBJETIVO: Comparar o uso do butil-2-cianoacrilato, mistura gelatina-resorcina-formaldeido (GRF) e sutura na estabilizacao de enxertos de cartilagem em coelhos. FORMA DE ESTUDO: Experimental. MATERIAL E METODO: Utilizaram-se 15 coelhos adultos da raca Nova Zelândia machos, de cujas orelhas foram ressecados 6 enxertos de cartilagem, fixados no periosteo da calvaria e unidos dois a dois com sutura, GRF e cianoacrilato. Apos 2, 6 e 12 semanas, grupos de 5 coelhos foram sacrificados e realizou-se avaliacao da distância de deslocamento do enxerto e analise histologica do processo inflamatorio tecidual e da adesao/deformidade das cartilagens. RESULTADOS: Houve deslocamento menor nas fixadas com GRF do que com cianoacrilato e sutura. O processo inflamatorio foi maior nos animais de 2 semanas, decaindo ate restar pequeno grau de fibrose em 12 semanas, de modo semelhante nas 3 fixacoes. Nao houve descolamento nem deformidade em nenhuma dupla de cartilagens fixada com sutura e o maior numero de cartilagens descoladas e deformadas se deu com o cianoacrilato. O numero de cartilagens deformadas foi diretamente proporcional ao numero de descoladas. Os dados foram significativos estatisticamente (p<0,05). CONCLUSAO: A mistura gelatina-resorcina-formaldeido mostrou ser um metodo de estabilizacao de enxertos de cartilagem em coelhos superior ao butil-2-cianoacrilato em todas as fixacoes, e a sutura na fixacao cartilagem-osso.

Evaluation of the systemic use of riluzole in post-traumatic facial nerve regeneration: experimental study in rabbits.

Conclusions. Riluzole promoted increase and/or preservation of axon density in the animals treated with this drug as compared to the control group; it did not increase the mean diameter of facial nerve fibres as compared to the non-treated group; and it did not provide a better functional motor recovery than in the control group. Objective. Traumatic peripheral facial paralysis is a frequent affection. In incomplete nerve injuries, systemic drugs acting on regeneration may decrease the patients period of morbidity. This study aimed to determine the effect of the drug riluzole on regeneration of the facial nerve of rabbits submitted to post-traumatic facial paralysis. Materials and methods. Eighteen rabbits were submitted to compression of the facial nerve and divided into control (A) and treated (B) groups. The animals were sacrificed 4 weeks after the injury and their nerves were studied regarding density of myelinated axons and measure of external axon diameters. Results. Partial functional recovery was observed within 2 weeks and complete recovery 5 weeks after injury. Mean neural density was 12 679.7 axons/mm2 (SD±237.5) in group A, and 19 073.8 axons/mm2 (SD±3549.9) in group B. Group A presented less than two-thirds the density of group B. There was no statistical difference in axon diameters between the studied groups.

Regeneração pós-traumática do nervo facial em coelhos

Posttraumatic facial paralysis is a frequent disease. This work studies posttraumatic regeneration of the facial nerve in rabbits. Functional and histological analysis compared injured and normal nerves on opposite sides. The left facial nerve trunk of twenty rabbits were subjectedto compression lesion, and sacrificed after two (subgroup AL), four (BL) and six (CL) weeks. Comparison between groups was made by analysing total and partial densities of myelinated axons. STATISTICAL ANALYSIS: Tukey Method (p<0.05). RESULTS:There was partial functional recovery after two weeks, and complete recovery after five weeks. Qualitative analysis demonstrated a degenerative pattern in the AL group, with an increased tissue inflammatory process. Evident regeneration signs were observed in the BL group, and almost complete regeneration was seen in the CL group. Normal nerves (N) had an average TD of 15705.59 and average PD of 21800.75. The BL group had an average TD of 10818.55 and an average PD of 15340.56. The CL group had an average TD of 13920.36 and an average PD of 16589.15. The BL group had an average TD of N equal to 68.88%, and the CL group had an average TD of N equal to 88,63% (statistically significant). N showed a significant higher PD than injured nerves. However, this was not statistically different between BL and CL subgroups. Nerve DT was a more reliable method than PD in this study.

Quantitative histological analysis of the mandibular branch of the facial nerve in rats

PURPOSE To establish a model to quantitative histological analysis of the mandibular branch of the facial nerve in rats. METHODS Eleven Wistar rats had their right and left mandibular branches of the facial nerve surgically removed and were sacrificed afterwards. Quantitative histological analysis was performed with: a) partial number of axons; b) partial area of the transversal cut of the nerve (9000 μm(2)); c) partial density. The averages of partial density were obtained. The statistical study was established by Wilcoxon test (p=0.05). RESULTS In relation to density of axons, comparison between sides shows no statistically significant difference (p=0.248; p=0.533). Mean partial density of distal and proximal samples was, respectively, 0.18 ± 0.02 and 0.19 ± 0.02 axons/μm(2). Comparison between proximal and distal samples shows no statistically significant difference (p=0.859; p=0.182). CONCLUSION This study has successfully established a model to histological quantitative analysis of the mandibular branch of the facial nerve in rats.

New Experimental Model of Facial Nerve Function and Integrity to Evaluate Regeneration

Objectives: The ideal animal model for nerve regeneration studies is an object of controversy because all models described by the literature have advantages and disadvantages. Small animals such as rats have been repeatedly used in experimental procedures because of their easy caretaking and handling, resistance to manipulation and infections, and low cost. In this case, rats have the additional benefit of tolerating bilateral facial paralysis. This study aimed to describe the histologic and functional (electroneuromyographic) patterns of the mandibular branch of the facial nerve of Wistar rats in order to create a new experimental model of facial nerve regeneration. Methods: Forty-two male Wistar rats were submitted to neurophysiologic evaluation by a nerve conduction test of the mandibular branch of the facial nerve to obtain the compound muscle action potential. Twelve of these rats had the mandibular branch of the facial nerve surgically removed and submitted to histologic analysis (total axon number, partial axonal density, and axonal diameter) of the proximal and distal nerve segments. Results: There was no statistical difference in the functional and histologic variables studied. Conclusion: These new histologic and functional standards of the mandibular branch of the facial nerve of rats establish an objective, easy, and greatly reproducible model for future facial nerve regeneration studies.

Stem Cells within PGAt Observed In Vivo after 6 Weeks Enhance Facial Nerve Regeneration

Objectives: Autografting, the gold-standard method for facial nerve repair with tissue loss, in association with high quality scaffolds and cell implants, has disclosed distinct experimental outcomes. The aim of the study was to evaluate the functional and histological effects of bone marrow stem cells (BMSC) combined with polyglycolic acid tube (PGAt) in autografted rat facial nerves. Methods: After neurotmesis of the mandibular branch of the rat facial nerve, surgical repair consisted of nerve autografting (groups A-E), contained in PGAt (groups B-E), filled with basement membrane matrix (groups C-E), with undifferentiated BMSC (group D) or Schwann-like cells that had differentiated from BMSC (group E). Axon morphometrics and an objective compound muscle action potentials (CMAP) analysis were conducted. Immunofluorescence assays were carried out with Schwann cell marker S100 and anti-B-galactosidase to label exogenous cells. Results: Six weeks after surgery, animals from either cell-containing group had mean CMAP amplitudes significantly higher than control groups. Differently from other groups, facial nerves with Schwann-like cells implants had mean axonal densities within reference values. This same group had the highest mean axonal diameter in distal segments. We observed expression of the reporter gene LacZ in nerve cells in the graft and distally from it in groups D and E. Group E cells had LacZ coexpressed with S100. Conclusions: Regeneration of the facial nerve was improved by BMSC within PGAt in rats, yet Schwann-like cells were associated with superior effects. Accordingly, groups D and E had BMSC integrated in neural tissue with maintenance of former cell phenotype for 6 weeks.