2 The condition, current treatments and procedure
2.1 Neural tube defects happen because the neural tube does not fuse during early embryonic development. Open neural tube defects are those in which the affected region of the neural tube is exposed on the body's surface. The most common neural tube defect is spina bifida where the defect is in the spine. Myelomeningocele (open spina bifida) is the most severe type of spina bifida, in which the baby's spinal canal remains open along several vertebrae in the back. The spinal cord and protective membranes around it push out and form a sac which is exposed on the baby's back. Children born with myelomeningocele may experience motor neurological deficits including muscle weakness and paralysis of the lower limbs, sensory deficit, bowel, bladder and sexual dysfunctions and learning difficulties. The condition can be associated with Chiari II malformation (hindbrain herniation) and hydrocephalus.
2.2 Conventional treatment for myelomeningocele (open spina bifida) is immediate surgical repair of the defect within days of birth to prevent further damage to nervous tissue and reduce the risk of central nervous system infection. The immediate management may also include ventricular-peritoneal shunt placement to relieve hydrocephalus. The condition can also be treated prenatally with the aim of decreasing morbidity in the child.
2.3 Fetoscopic prenatal repair is typically done before 26 weeks of pregnancy. It is done using general anaesthesia and with partial CO2 insufflation of the uterine cavity. Under ultrasound guidance an endoscope is introduced through a port followed by the introduction of additional ports to allow the passage of instruments. Once the fetus is positioned adequately, the skin around the fetal neural placode/elements is dissected. Occasionally a biocellulose patch may be placed between the neural elements (defect) and the skin. Myofascial flaps are created and sutured on top of the biocellulose patch. The skin is then sutured using interrupted stitches over the patch or, for a large defect, a dermal regeneration patch substitute can be used for repair.
2.4 A number of variations to the procedure have been described and the technique is still evolving.