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

Abstract

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

Percutaneous minimally invasive fetoscopic surgery for spina bifida aperta. Part I: surgical technique and perioperative outcome

“…The technically more simple fetoscopic closures have been critisized by surgeons who believe that fetal repair must adhere to the postnatal standards of repair. This non‐evidence based practice was recently challenged by Pedreira and colleagues from Sao Paulo. They developed and recently introduced clinically a simplified fetoscopic spina bifida closure technique in sheep, which resulted in better preservation of nerve tissue and less adherence of the spinal cord to the scar when compared with the classic technique performed by a neurosurgeon.…”

Cryopreserved human umbilical cord versus biocellulose film for prenatal spina bifida repair in a physiologic rat model

“…We anticipated 100% cellular infiltration into the HUC patches on the basis of our previous sheep study and human cases. In the BCF patches, we anticipated the cellular infiltration to be less than 30% on the basis of the previous studies . With the assumption that HUC would promote cellular migration better than BCF and using a one‐sided Fisher's exact test, we determined that seven fetuses would be required in each arm (14 fetuses total) to detect a difference with power set at 80% and p‐ value set to 0.05.…”

Tissue Engineering Strategies for Fetal Myelomeningocele Repair in Animal Models

“…To date, experimental studies of tissue engineering approaches to prenatal repair of MMC can be divided into 2 groups according to the goals of the investigators: (1) to prevent amniotic fluid-induced neural damage by providing coverage of the defect using scaffolds [31,32,33,34,35,36,37,38] and (2) to place a scaffold and/or cells between the neural tissue and the skin repair to prevent adhesion of the repair to the cord (tethering) and/or to provide neurotrophic factors or regenerate neural tissue [39,40,41,42,43,44]. …”