Determination of anatomic level of myelomeningocele by prenatal ultrasound

Absence of a Hernia Sack in Patients Undergoing Prenatal Repair of Spina Bifida Increases the Risk of Developing Shunt-Dependent Hydrocephalus

Spina bifida aperta (SBA), with (myelomeningocele) or without (myeloschisis) a hernia sack, is the most common congenital defect of the central nervous system. Prenatal surgical closure of SBA lowers the risk for developing shunt-dependent hydrocephalus, which offers a chance at improved motor, urinary, and gastrointestinal function. A total of 96 patients who had undergone open surgery prenatal repair for SBA were analyzed. The patients were divided into two groups: Group I-12 patients (12.5%)-without a hernia sack (myeloschisis) and Group II-84 patients (87.5%)-with a hernia sack (myelomeningocele). In this study, we demonstrated that prenatal SBA repair was statistically significantly less often associated with the need for ventriculoperitoneal shunting (p > 0.00001). The shunting was statistically significantly more often required in patients from Group I (p > 0.004). The absence of a hernia sack increases the risk for developing shunt-dependent hydrocephalus in patients after prenatal SBA repair. However, as prenatal SBA repair is associated with better motor, urinary, and gastrointestinal function, increased risk of developing shunt-dependent hydrocephalus in fetuses without a hernia sack should not be treated as a contraindication to prenatal intervention.

Fetal Surgery for Myelomeningocele: Neurosurgical Perspectives

More than 30 years have elapsed since it was recognised that folic acid supplementation could substantially reduce the risk of open neural tube defects (ONTDs). During that time, many countries have adopted policies of food fortification with demonstrable reduction in the incidence of both cranial and spinal ONTDs. Improved prenatal detection and termination has also resulted in a reduction in the number of affected live births. Nonetheless, in the USA about 1500 children, and in the UK around 500 children are born each year with myelomeningocele (MMC) and so the management of MMC and its complications continues to constitute a significant clinical workload for many paediatric neurosurgical units around the world.Until recently, the options available following antenatal diagnosis of MMC were termination of pregnancy or postnatal repair. As a result of the MOMS trial, prenatal repair has become an additional option in selected cases (Adzick et al., N Engl J Med 364(11):993-1004, 2011). Fetal surgery for myelomeningocele is now offered in more than 30 centres worldwide. The aim of this chapter is to review the experimental basis of prenatal repair of MMC, to critically evaluate the neurosurgical implications of this intervention and to describe the technique of 'open' repair, comparing this with emerging minimally invasive alternatives.