Reconstrucción del nervio alveolar inferior con aloinjerto de nervio acelular humano en resección mandibular / Reconstruction of the inferior alveolar nerve with human acellular nerve allograft in mandibular resection

La reconstrucción de nervios periféricos con aloinjertos nerviosos acelulares humanos en neurocirugía ha sido bastante estudiada estableciendo su predictibilidad y éxito en intervenciones principalmente en los nervios digitales de las manos. En cirugía maxilofacial existe una creciente investigación para poder restaurar el nervio alveolar inferior en cirugías de resección mandibular en donde la extirpación de esta estructura nerviosa es inevitable. El objetivo de esta publicación es mostrar un reporte de un caso en donde se realizó la reconstrucción del nervio alveolar inferior con aloinjerto de nervio acelular humano (Avance® Nerve Graft, Axogen) con microcirugía para poder proveer de sensibilidad a la región de la cara afectada en un paciente reconstruido con un injerto de fíbula microvascularizada posterior a una hemimandibulectomía por ameloblastoma plexiforme.

The reconstruction of peripheral nerves with allografts of human acellular nerves in neurosurgery is well studied, establishing its predictability and success in interventions mainly in the digital nerves of the hands. In maxillofacial surgery there is a growing investigation to be able to restore the inferior alveolar nerve in mandibular resection surgeries where the removal of this nervous structure is inevitable. The objective of this publication is to show a case report in which the reconstruction of the inferior alveolar nerve was performed with human acellular nerve allograft (Avance® Nerve Graft, Axogen) with microsurgery in order to provide sensitivity to the region of the affected face in a reconstructed patient with a microvascularized bone fibula graft after hemimandibulectomy due to plexiform ameloblastoma.

Neurorrafia do ramo bucal dorsal do nervo facial em coelhos com proteção de segmento intestinal alógeno / Neurorrhaphy of the dorsal buccal branch of facial nerve in rabbits with protection o f allograft intestinal segment

Foram utilizados 18 coelhos, Nova Zelândia, machos, adultos, para avaliação clínica e histológica do reparo do ramo bucal dorsal do nervo facial, decorridos 15, 30 e 60 dias de pós-operatório (PO). Os animais foram distribuídos em dois grupos para secção e aproximação epineural do ramo bucal com fio náilon monofilamentoso 10-0. Nos animais do grupo I, o nervo foi revestido com proteção de segmento de jejuno alógeno conservado em glicerina a 98% e o grupo II apenas aplicação de sutura epineural. Nos coelhos dos dois grupos ocorreu retorno da movimentação do lábio superior a partir da oitava semana.Verificou-se infiltrados celulares e células gigantes com fibrose desorganizada e fibras colágenas do envoltório alógeno entremeadas ao tecido conjuntivo. Aos 15 e 30 dias de PO, os cotos distais deambos os grupos encontravam-se com degeneração walleriana e aos 60 dias, com fibras regeneradas. A reparação do ramo bucal dorsal do nervo facial com o segmento intestinal não foi significativamente diferente nos coelhos do controle, quanto à avaliação de recuperação funcional e histológica.

18 rabbits, New Zealand, males, adults were used for clinical and histological evaluation of repair dorsal buccal branch of facial nerve after 15, 30 and 60 days postoperatively (PO). The animals were divided into two groups for transection and 10-0 nylon monofilament epineural suture of buccal branch. In animals in Group I, the nerve was coated with protection of jejunum allograft preserved in glycerin 98% and in group II was applied epineural suture. Both groups occurred the return of movement of the upper lip from the eighth week. There was infiltrated cellular and giant cells with fibrosis unsystematic and collagen fibers of the allograft jejunum joing to the connective tissue. At 15 and 30 days of PO, the distal nerve stumps of both groups were found with degeneration wallerian and in 60 days, regenerated fibers. The repair of the dorsal buccal branch offacial nerve with the allograft wasn’t significantly different between the control rabbits as to the assessment of histological and functional recovery.

Avaliação da sensibilidade após neurorrafia término-lateral de nervos digitais: nota prévia / Sensory evaluation after termino-lateral neurorrhaphy of digital nerves: a prior note

Objetivo: Demonstrar, em caráter preliminar, a viabilidade da anastomose término-lateral entre dois nervos, conforme já revelado por alguns estudos experimentais utilizando tanto nervo sensitivo como motor. Material: Uma série de nove nervos digitais, em cinco pacientes, entre os 12 casos operados no período de junho de 1996 a outubro de 1998, foi revista. O tempo de seguimento foi em média de 27,8 meses. O método de avaliação serviu-se de três testes para aquilatar a qualidade sensitiva: Semmes-Weinstein, discriminação entre dois pontos e localização do estímulo, além de um questionário para avaliação subjetiva. Avaliaram-se tanto a área receptora como a área doadora. Resultado: Identificou-se diminuição da sensibilidade no território do nervo doador ao mesmo tempo em que se verificou ganho sensitivo na área receptora. Conclusão: A técnica analisada pode ser mais uma opção na reconstrução nervosa, devendo ser reservada para casos especiais. O procedimento, simples e rápido, proporcionou, nesta série, melhora sensitiva da área anestésica, mas ainda necessita de validação clínica, tratando-se no momento apenas de resultados preliminares

Non-neuronal cells are not the limiting factor for the low axonal regeneration in C57BL/6J mice

Peripheral axonal regeneration was investigated in adult male mice of the C57BL/6J (C), BALB/cJ (B) and A/J (A) strains and in their F1 descendants using a predegenerated nerve transplantation model. Four types of transplants were performed: 1) isotransplants between animals of the C, B and A strains; 2) donors of the C strain and recipients of the C x B and C x A breeding; 3) donors of the B strain and recipients of the C x B breeding, and 4) donors of the A strain and recipients of the C x A breeding. Donors had the left sciatic nerve transected and two weeks later a segment of the distal stump was transplanted into the recipient. Four weeks after transplantation the regenerated nerves were used to determine the total number of regenerated myelinated fibers (TMF), diameter of myelinated fibers (FD) and myelin thickness (MT). The highest TMF values were obtained in the groups where C57BL/6J mice were the donors (C to F1 (C x B) = 4658 + OR - 304; C to F1 (C x A) = 3899 + OR - 198). Also, A/J grafts led to a significantly higher TMF (A to F1 (C x A) = 3933 + OR - 565). Additionally, isotransplant experiments showed that when the nerve is previously degenerated, C57BL/6J mice display the largest number of myelinated fibers (C to C = 3136 + OR - 287; B to B = 2759 + OR - 170, and A to A = 2835 + OR - 239). We also observed that when C57BL/6J was the graft donor, FD was the highest and MT did not differ significantly when compared with the other groups. These morphometric results reinforce the idea that Schwann cells and the nerve environment of C57BL/6J provide enough support to the regenerative process. In this respect, the present results support the hypothesis that the non-neuronal cells, mainly Schwann cells, present in the sciatic nerve of C57BL/6J mice are not the main limiting factor responsible for low axonal regeneration

Pontes de nervos perifericos no auxilio da regeneracao da medula espinhal / Peripheral nerves bridges in aid of spinal cord regeneration

Ao contrario da grande capacidade de regeneracao observada em nervos perifericos, o tecido nervoso central adulto apresenta minima regeneracao apos trauma. Apesar dos rearranjos sinapticos subsequentes ao trauma, lesoes medulares resultam em deficits permanentes. Intervencoes no microambiente neuronal sao necessarias para promover regeneracao de neuronios medulares. Neste trabalho utilizamos pontos de nervos interligando regioes da medula espinhal previamente lesadas, fornecendo assim microambiente favoravel a regeneracao de neuronios centrais...

Regeneration of cat's optic nerve and its funtional recovery

The optic nerve of adult mammals can regenerate when a permissive environment is provided with a peripheral nerve (PN) graft. Using this method of PN transplantation, we have studied regeneration of the optic nerve in adult cats. Number of retinal ganglion cells (RGCs) which regenerated their axons through the PN graft corresponds to 3-4 percent of the total RGC population. The RGCs with regenerated axons distributed widely from central to peripheral retinas. Of the known cell types of cat's RGCs, alpha, Beta, gamma and other cells, alpha cells revealed the greatest capacity to regenerate their axons. Dendritic field diameters of most RGCs with regenerated axons were preserved. These regenerated axons were, however, mostly unmyelinated when surveyed by electron microscopy at two months after the transplantation surgery. The regenerated axons revealed normal physiological propeties in response to visual stimuli and were classifiable into Y, X or W cells. In accordance with morphological data, Y cells (morphological alpha cells) were more frequently sampled than in normal retinas, whereas the occurrences of X cells (morphological Beta cells) and other cells were unchanged or decreased. These results suggest that RGCs retain their physiological function during axonal regeneration, and RGCs with large soma and large dendritic field (Y or alpha cells) have the greatest capacity to regenerate their axons.

Injertos nerviosos vascularizados: estudio experimental / Vascularized nerve grafts: experimental study

La vascularizacion de los injertos nerviosos es de primordial importancia para la supervivencia del injerto. Preservamos el pediculo proximal en el nervio ciatico del conejo y reparamos un defecto de 4.5 cm. Un modelo experimental de injertos nerviosos vascularizados es presentado como una alternativa para la recuperacion mas rapida de la funcion. Utilizamos 18 conejos, en el lado derecho se efectuo un injerto de 4.5 cm preservando el pediculo vascular, en el lado contralateral se efectuo un injerto de la misma longitud sin preservar ningun pediculo. La neurorrafia se efectuo con nylon 10/0 y microscopio quirurgico. Posteriormente se sacrificaron los animales entre la 5 y la 15 semana del postoperatorio y los nervios se estudiaron con microscopio de luz. El analisis cuantitativo se efectuo en un computador teniendo en cuenta principalmente el espesor de la vaina de mielina. Este experimento demostro que cuando se efectua un injertpo nervioso vascularizado la rata de la maduracion axonal se aumenta hasta 2 veces la rata observada en injertos convencionales. La maduracion de las fibras ocurre de una manera mas rapida y aun utilizando la misma longitud del nervio no se presento ningun caso de necrosis central. En conclusion los resultados son mas favorables en cuanto a regeneracion cuando se utiliza un injerto nervioso vascularizado