Percutaneous fetoscopic patch coverage of experimental lumbosacral full-thickness skin lesions in sheep

Araújo³

et al. 2009

Acta Cir. Bras.

Purpose: To develop a simplified technique for antenatal correction of a meningomyelocele -like defect in fetal sheep to allow direct skin closure. Methods: A spinal defect was surgically created at 75 days of gestation in the fetuses of 36 pregnant sheep, 23 survived the surgery. At 102 days gestation, the defect was corrected in 14 cases (9 were left untreated). Skin surrounding the defect was dissected below the dermis to permit its edges to be approximated and sutured, without interposing any material to its edges. An interface material intended to protect the neural tissue from skin adhesion was used and the skin defect was completely closed over it. Pregnancy was allowed to continue up to 138 days gestation, the fetuses were submitted to macroscopic and microscopic analysis. Results: The defect was successfully corrected in 90.9% in the experimental group, and spontaneous closure occurred in 22.3% in the control group (p < 0.05). The survival rate after the creation and correction of the defect was 63.4% and 78% respectively. Conclusion: This simplified technique was successful in the correction a meningomyelocele-like defect, in the fetal sheep. Key words: Surgery. Fetal Therapies. Meningomyelocele. Spinal Dysraphism. Disease Models, Animal. Sheep. RESUMOObjetivo: Desenvolver uma técnica simplificada de correção pré-natal de defeito semelhante à mielomeningocele em fetos de ovelha permitindo um fechamento direto da pele. Métodos: Um defeito espinhal foi cirurgicamente criado com 75 dias de gestação, em 36 fetos de ovelha, 23 sobreviveram à cirurgia. Após 102 dias de gestação, o defeito foi corrigido em 14 casos (9 não foram tratados). A pele em volta do defeito foi dissecada abaixo da derme para permitir a aproximação direta das bordas através de sutura, sem a interposição de nenhum material entre a pele. Um material de interface foi colocado entre o tecido neural exposto e a pele, com o objetivo de evitar a adesão da medula à pele, que foi completamente fechada sobre o defeito. A gravidez foi mantida até 138 dias, os fetos foram submetidos a análises macroscópicas e microscópicas. Resultados: O defeito foi corrigido em 90.9% no grupo experimental, e o fechamento espontâneo ocorreu em 22.3% no grupo controle (p < 0.05). A taxa de sobrevivência após a criação do defeito e posteriormente a sua correção foi de 63,4% e 78%, respectivamente. Conclusão: Esta técnica simplificada teve sucesso na correção do defeito semelhante à mielomeningocele em feto de ovelha. Descritores: Cirurgia. Terapias Fetais. Meningomielocele. Disrafismo Espinal. Modelos Animais de Doenças. Ovinos.

Section: Discussionmentioning

confidence: 94%

“…In others, only the skin was removed, without involving muscle or any other planes below this level 6,24,25 . Observe that correction was sometimes performed a few weeks after the defect's creation and sometimes the defect was created and corrected at the same time 6,24,25 .…”

Section: Discussionmentioning

confidence: 99%

Simplified correction of a meningomyelocele-like defect in the ovine fetus

Abou-Jamra¹,

Araújo³

et al. 2009

Acta Cir. Bras.

“…In all these studies, the authors based their observations on analyses of the anatomical specimen, which is a lot more troublesome to prepare than what is needed to submit the samples to resonance, in our study. After the beginning of our study, four more studies were published in which myelomeningocele was surgically created in a sheep fetus, three of them from the same group of authors in San Francisco, United States [14][15][16]18 . All of them demonstrated that the defect created by this technique is histologically similar to myelomeningocele in humans.…”

Section: Discussionmentioning

confidence: 99%

“…In the second study 10 , we successfully developed a new corrective technique, using cellulose film to cover the deformity. Because of its similarity with the human fetus in size and anatomy, the ovine fetus has been the animal model of choice for developing new techniques in fetal surgery 7,[11][12][13][14][15][16][17][18] . Therefore, this corrective technique should be subsequently applied in ovine fetuses.…”

Section: Introductionmentioning

confidence: 99%

Validation of the ovine fetus as an experimental model for the human myelomeningocele defect

Pedreira

Oliveira²,

et al. 2007

Acta Cir. Bras.

PURPOSE: To produce a myelomeningocele-like human defect in the ovine fetus and validate this experimental model in our population. METHODS: A prospective study on 12 pregnant sheep of a crossed Hampshire/Down breed where a spinal defect was surgically created between Day 75 and Day 77 after conception. The technique consisted of a hysterotomy with exposure of fetal hind limbs and tail up to the mid spine. Fetal skin, paravertebral muscles, and 4 posterior spinal arches were excised, exposing the spinal cord. Duramater was opened and the medulla was incised until the medullar canal. Animals were euthanized at 139 days of gestation for fetal evaluation. The central nervous system was submitted to post-mortem magnetic resonance imaging (MRI) and the spine was submitted to pathological examination. RESULTS: The defect was created in 13 fetuses and 5 survived. Mean gestational age at necropsy was 121.6 days (varying from 93 to 145 days). Macroscopically, the defect was present in 4 cases. Microscopy revealed a flattened medulla with disappearance of the medullar canal and disruption of normal medullar architecture with neuronal apoptosis and/or fusion of the piamater and duramater. The MRI showed herniation of the cerebellum into the cervical canal and syringomyelia. CONCLUSIONS: The surgically produced defect mimics the defect found in the human fetus, including the Arnold-Chiari malformation. Post-mortem MRI was used for the first time in our study and proved an excellent alternative for demonstrating the cerebellar herniation. We standardized the technique for creating the defect in our population.

“…Maternal morbidity associated with open correction suggests that minimally invasive methods are the future of antenatal correction of myelomeningocele. Some authors have studied the endoscopic correction of this defect both in animal models (14)(15)(16) and in humans (17) -in…”

Section: Discussionmentioning

confidence: 99%

Comparison between two surgical techniques for prenatal correction of meningomyelocele in sheep

Herrera

Leme

et al. 2012

Einstein (São Paulo)

Objective: To compare the classical neurosurgical technique with a new simplified technique for prenatal repair of a myelomeningocelelike defect in sheep. Methods: A myelomeningocele-like defect (laminectomy and dural excision) was created in the lumbar region on day 90 of gestation in 9 pregnant sheep. Correction technique was randomized. In Group 1 the defect was corrected using the classic neurosurgical technique of three-layer suture (dura mater, muscle and skin closure) performed by a neurosurgeon. In Group 2, a fetal medicine specialist used a biosynthetic cellulose patch to protect the spinal cord and only the skin was sutured above it. Near term (day 132 of gestation) fetuses were sacrificed for pathological analysis. Results: There were two miscarriages and one maternal death. In total, six cases were available for pathological analysis, three in each group. In Group 1, there were adherence of the spinal cord to the scar (meningo-neural adhesion) and spinal cord architecture loss with posterior funiculus destruction and no visualization of grey matter. In Group 2, we observed in all cases formation of a neo-dura mater, separating the nervous tissue from adjacent muscles, and preserving the posterior funiculus and grey matter. Conclusion: The new simplified technique was better than the classic neurosurgical technique. It preserved the nervous tissue and prevented the adherence of the spinal cord to the scar. This suggests the current technique used for the correction of spina bifida in humans may need to be reassessed. de ovelhas. Métodos: Em 9 fetos, foi criado um defeito semelhante à mielomeningocele (laminectomia e excisão de dura-máter) no 90° dia de gestação. O tipo de correção foi randomizado. No Grupo 1, o defeito foi corrigido usando a técnica neurocirúrgica clássica, com a sutura de três camadas (dura-máter, músculo e pele), realizada por um neurocirurgião. No Grupo 2, um especialista em Medicina Fetal utilizou a técnica simplificada, colocando um fragmento de celulose biossintética sobre a medula e suturando apenas da pele sobre a celulose. Próximo ao termo da gestação (132 dias), os fetos foram sacrificados para análise anatomopatológica. Resultados: Ocorreram dois casos de aborto e uma morte materna, restando seis casos para avaliação -três em cada grupo. No Grupo 1, todos os casos mostraram aderência da medula à cicatriz (meningoadesão) e perda da arquitetura medular, com destruição do funículo posterior e perda da visualização da substância cinzenta. No Grupo 2, observou-se, em todos os casos, a formação de uma neodura-máter, separando o tecido nervoso do músculo adjacente, sendo que o funículo posterior e a substância cinzenta estavam preservados. Conclusão: A técnica simplificada foi superior à neurocirúrgica, com maior preservação da medula e evitando as aderências do tecido nervoso. Os presentes achados sugerem que a técnica utilizada atualmente na correção de mielomeningocele em fetos humanos deva ser reavaliada. Keywords