Rogério C. Abou-Jamra

Successful Fetal Surgery for the Repair of a ‘Myelomeningocele-Like’ Defect Created in the Fetal Rabbit

Objective: To study the correction of a ‘myelomeningocele-like’ defect in fetal rabbits. Methods: Twelve pregnant rabbits had a spinal defect surgically created in 40 of their fetuses at 23 days of gestation. Immediate repair was performed in 30 fetuses (group I), and 10 remained uncorrected (group II). After 30 days, the fetuses were harvested and the anatomopathological aspects where compared using Fisher’s exact test. Results: Three different techniques to apply a cellulose graft were used for correction in 8 (technique A), 7 (technique B), and 15 animals (technique C), but only one (technique C) was successful. The survival rate at 30 days was 66.7% (10/15) in group I and 80% (8/10) in group II. A ‘myelomeningocele-like’ defect was present in all fetuses in group II, while in group I the defect was successfully repaired in 80% of the surviving fetuses (p < 0.01). Conclusion: The surgically created spinal defect was successfully repaired, and also the fetal rabbit could be established as a model for the study of intrauterine correction of a myelomeningocele-like defect.

Gasless Fetoscopy: A New Approach to Endoscopic Closure of a Lumbar Skin Defect in Fetal Sheep

Objective: To develop a new endoscopic approach to the correction of a myelomeningocele-like defect in fetal sheep. Methods: The fetuses of 9 pregnant ewes, with an average gestational age of 115 days, were subjected to a 3.0 × 2.0 cm removal of the skin over the lumbar spine, performed through hysterotomy. The uterus was closed, and three 5-mm endoscopic cannulas, without valve mechanisms, were inserted. In the pilot phase (2 animals), we initially worked exclusively in the amniotic fluid space. In the study phase, we partially withdrew the fetus from the amniotic fluid to completely expose its back. By simply allowing air to enter the amniotic cavity (without gas injection), a working space was created using a uterine lift device. The skin around the defect was dissected, and a biosynthetic cellulose material was applied to cover the area. A continuous suture of the skin was performed to completely hide the material. Results: The combined air/fluid space allowed the skin to be successfully closed in 6 out of 7 cases in the study phase. All fetuses were alive at the end of the procedures. Time to complete the endoscopic part of the procedure fell from 3 to 1 h by the end of this series. Premature birth occurred in 2 of the 4 cases allowed to continue with the pregnancy. Conclusion: A new gasless fetoscopic surgery technique was developed as an alternative to current techniques used for fetal endoscopic surgery.

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

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.

A Different Technique to Create a ‘Myelomeningocele-Like’ Defect in the Fetal Rabbit

Objective: To evaluate the fetal survival rate using a modified technique to surgically create a ‘myelomeningocele-like’ defect in a rabbit model. Methods: Six white New Zealand rabbits had a spinal defect created in their fetuses at 23 days of gestation. At 30 days of gestation, the fetuses were harvested for anatomo-pathologic evaluation. Results: The defect was created in 19 fetuses and an attempt to correct it was made in 15 cases (group I), and 4 fetuses where left without correction (group II). At 30 days, a ‘myelomeningocele-like’ defect was present in all surviving fetuses. The total survival rate was 73.68% (14/19); 11 fetus survived in group I and 3 in group II. Conclusion: The technical modifications, including fetal positioning and exposure of its back prior to the incision of the lamina, associated with a different technique for myometrium closure, offer an alternative and probably safer method to surgically create a spinal defect in the fetal rabbit.

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

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.

Estudo de uma nova técnica para criação cirúrgica de um defeito semelhante a meningomielocele em fetos de coelhos

OBJETIVO: Avaliar a sobrevida fetal usando uma nova tecnica cirurgica para criacao de um defeito semelhante a meningomielocele em fetos de coelho. METODOS: Foram utilizadas seis coelhas da linhagem Nova Zelândia que tiveram um defeito espinhal criado em seus fetos no 23° dia de gestacao. O defeito foi criado em 19 fetos e a tentativa de correcao foi feita em 15 casos (grupo I), 4 fetos permaneceram sem correcao (grupo II). No 30° dia de gestacao, os fetos foram submetidos a avaliacao anatomo-patologica. RESULTADOS: No 30° dia a meningomielocele estava presente em todos os fetos sobreviventes. A sobrevida total foi de 73,68% (14/19), 11 fetos sobreviveram no grupo I, e 3 no grupo II. CONCLUSAO: A tecnica modificada apresenta sobrevida fetal satisfatoria, no modelo experimental de criacao de defeito espinhal em fetos.

OC124: A different technique for the correction of a ‘myelomeningocele-like’ defect in ovine fetus

Objective: To evaluate the accuracy of three-dimensional ultrasonography in predicting the level of the defect in spine bifida. Patients and Methods: Between January 2005 and January 2006, the level of spine bifida was evaluated prenatally on three-dimensional ultrasonography (3DUS) using the rendered bone mode. All cases underwent postnatal surgery immediately after birth. Prenatal results obtained on 3DUS were compared to surgical level and to radiological level. Results: Up to now, 21 cases were completely evaluated. The correct surgical level was predicted in 9 (42.86%) cases; difference of one level was observed in 9 (42.86%) fetuses and difference of 2 levels in 3 (14.28%). Up to 1 and to 2 levels of agreement were observed in 18 (85.71%) and 21 (100%) cases. Using the postnatal radiological diagnosis, the correct level was predicted in 9 (42.86%) cases; difference of one level was observed in 9 (42.86%) fetuses and difference of 2 levels in 2 (14.29%). Up to 1 and to 2 levels of agreement were observed in 18 (85.71%) and 21 (100%) cases respectively. Conclusions: In our experience, 3DUS (rendered skeletal mode) is a good method to evaluate the level of spine bifida, with difference of two levels in 14.29% of cases when compared to postnatal surgical and radiological diagnosis.

Modification of the gasless fetoscopy technique for the treatment of large myelomeningocele: a study in sheep

OBJECTIVE To change the gasless fetoscopy technique in order to reduce the diameter of entry orifices in the myometrium. METHODS Seven pregnant ewes were submitted to fetoscopy for repairing a large skin defect measuring 4.0 × 3.0 cm, created in the fetal lumbar region at the gestational age of 100 days. The defect was repaired through continuous suture of the skin with approximation of borders. Gasless fetoscopy was used for performing the suture with three orifices to allow entry of the trocar into the myometrium. A 5.0-mm optical trocar, and 3.5-mm grasping, dissecting and suturing forceps were used. After surgery, pregnancy was maintained until the animals were euthanized on the 133rd day of gestation, and the fetuses were evaluated. RESULTS Seven pregnant ewes underwent surgery; the first two cases were characterized as the Pilot Group, in which the endoscopic technique was modified and caliber reduction was possible in two out of three entry orifices in the myometrium. In the five remaining cases (Study Group), the repair was successfully carried out in all the fetuses, and the mean duration of fetoscopy was 98 minutes. There was a case of maternal death attributed to intrauterine infection. Mean intrauterine permanence after surgery was 12 days. CONCLUSIONS The technique was successfully modified, allowing reduction of the uterine orifices necessary to perform the repair of a skin defect in the fetal lumbar region through a new fetoscopy technique. The impact of this modification in repair of myelomeningocele in human fetuses should be studied.

P42.01: Alternative technique for prenatal correction of myelomeningocele in cases of myeloschisis

Purpose: In up to 20–30% of myelomeningocele (MMC) cases corrected in utero, fetal skin closure cannot be accomplished due to the size of the defect (myeloschisis). Our aim was to develop a new technique to correct myeloschisis. Method: A skin defect at lumbar fetal region (4 × 3cm) was created at 100 days’ gestation in 7 ovine fetuses, and was correct applying a new endoscopic ‘‘gasless’’ technique (Pedreira et al., 2008). The skin edges were approximated under tension (but not closed) using a continuous running suture and an interposed bovine tendon derived dermal matrix (Integra USA) (3 × 2 cm). This was placed above a biosynthetic cellulose material (Nexfill Brazil) to be used as duramater substitute. At term, fetuses where harvested and the wound was analysed both macro and microscopically. Results: A total of 7 fetuses were operated, in the first two cases we needed to change to an open surgery approach and the other 5 where successfully closed endoscopically. All fetuses survived to the end of the procedure. One maternal death (infection related) occurred the day after the procedure. Two pre-term deliveries occurred days 3 and 4 after the procedure. At birth matrix adherence to the wound edges was observed in all cases. Pathological analysis performed at 3, 4, 15, 21, 25 and 35 days after surgery showed the expected normal fibroblast migration into the dermal matrix and its integration with the adjacent fetal dermis. Conclusions: Dermal matrix can be used as an alternative in cases where primary skin closure in spina bifida cannot be accomplished.

OC125: New “suspension” endoscopic technique to correct fetal myelomeningocele: a pilot study in the ovine model

days 74 and 78 after conception. At 98 to 112 days an attempt to correct the defect was made in 11 cases and 6 fetuses remained uncorrected (control group). Using an open uterine approach the fetus was partially exposed from its tail to the lumbar spine. The skin around the defect was dissected below the dermis to permit the placement of an interface material over the exposed neural tissue and the skin. The skin was then completely closed over the defect using a separated suture. Pregnancy was allowed to continue and lambs were sacrificed between 137–145 days of gestation. The specimens were submitted to macroscopic and microscopic analysis. The correction was considered successful when more then 70% of the skin was closed. Results: The survival rate after the creation of the defect was 68% (17/25) and 90% (10/11) after correction. Macroscopically the skin was completely closed in 7 out of 10 cases in the corrected group and in 2 out of 6 cases in the control group. Neverthless 80% (8/10) were considered successful in the corrected cases. Transverse sections of fetal spine were microscopically analyzed in average 132 days of gestation (range 118–145 days) and the medulla had been reached in all fetuses in both groups. Conclusions: The new simplified technique was successful in the correction of the defect. We believe it can be more easily applied in an endoscopic approach for correction a human myelomeningocele.