Amniotic Fluid Exchange for the Prevention of Neural Tissue Damage in Myelomeningocele:An Alternative Minimally Invasive Methodto Open in utero Surgery

Abstract

Objective: Experimental studies have shown that neural tissue damage in myelomeningocele (MMC) is acquired, resulting from exposure of neural tissue to amniotic fluid (AF). Similar to neural tissue damage in MMC, in gastroschisis, intestines exposed to AF are damaged. In gastroschisis, intestinal damage can be prevented by changing the composition of the AF with partial AF exchanges. An experimental study was performed to investigate whether the neural tissue damage in MMC can be prevented by AF exchange. Methods: Thirteen-day-old fertilized chick eggs were used. In group 1, the amnio-allantoic membrane was opened to create a common cavity, and MMC was created (MMC-only group). In group 2, after creation of MMC, amnio-allantoic fluid exchange was performed (MMC-plus-exchange group). Chicks were extirpated for histopathologic examination 5 days later. Results: While edema, focal calcification, fibrosis, capillary cell proliferation and scattered mononuclear cells were observed in the MMC-only group, histopathologic changes were mild in the exchange group. The number of neuron-specific enolase stainings (+) neural cell count was significantly higher in the exchange group compared to the MMC-only group (p < 0.01). Conclusion: Exposure of MMC to AF causes structural neural tissue damage that can be prevented by AF exchange. AF exchange is minimally invasive compared to open in utero surgery for the closure of MMC. By AF exchange, neural tissue damage that occurs during the gestational period may be prevented.

Evaluation and Management of Lumbosacral Myelomeningoceles in Children

“…Amniotic fluid exchange was also previously reported by Olguner et al [16] and they concluded that the exposure of myelomeningocele to amniotic fluid causes structural neural tissue damage that can be prevented by amniotic fluid exchange. This is an experimental study performed in chick eggs and not proven in humans [16]. In our series, we performed repair of myelomeningocele by reconstructing the neural placode and closing the dura in a watertight fashion.…”

“…Endoscopic coverage of foetal myelomeningocele in utero is recently and widely performed by many surgeons but its benefits on neurological recovery has not been understood yet [14,15]. Amniotic fluid exchange was also previously reported by Olguner et al [16] and they concluded that the exposure of myelomeningocele to amniotic fluid causes structural neural tissue damage that can be prevented by amniotic fluid exchange. This is an experimental study performed in chick eggs and not proven in humans [16].…”

Fetal surgery for neural tube defects

“…The fact that aminotic fluid exchange might prevent neural tissue damage in a chick embryo model suggests that at least a portion of the damage might be from chemical neurotoxicity. 18 It has been suggested that fetal meconium might play a role in this. 19 Laminectomy in early-gestation fetal sheep might result in the hindbrain hernia that is a component of the Chiari II malformation.…”

Reduction in neural injury with earlier delivery in a mouse model of congenital myelomeningocele

“…Gastroschisis (abdominal wall defect) has been managed with elective cesarean delivery primar ily to prevent bowel damage during labor, a notion that has been challenged when similar outcomes were found when elective cesarean delivery was compared with nor mal delivery. 21 In that study, however, cesarean deliveries were late, and the study cannot be used to test the current hypothesis based on a hostile amniotic environment. Re cent studies including cases managed with elective cesar ean delivery around 34 weeks of gestation showed better neonatal outcome in comparison with controls regarding tolerance of feeding and hospital stay.…”