Open spina bifida develops when the spine fails to close at some point along its length during fetal development.
Failure of the vertebrae, the bony part of the spinal column, to close around the spinal cord results in different forms of spina bifida. Myelomeningocele (MMC) is the most common type and occurs when both the meninges (membranous coverings) and the spinal cord protrude through the spinal defect. Myeloschisis is the most severe type and occurs when the spinal cord protrudes with no meninges covering the defect. These forms of spina bifida are oftentimes accompanied by a condition known as Arnold Chiari II Malformation, or herniation of the hindbrain (brain stem). When cerebral spinal fluid (CSF) escapes from the open spinal defect, it causes the hindbrain to descend into the spinal canal. This blocks CSF circulation and may lead to hydrocephalus, or accumulation of CSF in the brain.
MMC leads to injury and loss of spinal cord tissue at and below the defect. The abnormal spinal cord development, intrauterine trauma, and the toxic exposure to amniotic fluid may contribute significantly to the newborn’s neurological status (“two-hit hypothesis”). Because of these in-utero factors, fetuses with open spina bifida may benefit from correction before birth to improve function after birth.
In 2003, the NIH sponsored a multi-center randomized controlled trial of in utero repair of MMC vs. standard neonatal repair, the Management of Myelomeningocele Study (MOMS), the results of which were published in 2011. Prenatal repair resulted in reduction of the need of shunting at 12 months of age, decreased rate of hindbrain herniation by one-third at 12 months, doubling of the ability to ambulate without the assistance of orthotics, and produced a level of function that was two or more levels better than expected according to anatomic levels. However, the in utero repair was performed via open maternal-fetal surgery, which means the mother’s abdomen is opened (laparotomy) and her uterus is opened (hysterotomy), and was associated with significant risks, including higher rates of preterm birth, fetal bradycardia, oligohydramnios, placental abruption, pulmonary edema, maternal transfusion at delivery, and a 35% risk of uterine thinning or dehiscence or rupture. Furthermore, the legacy of open in utero repair in regards to a patient’s future pregnancies is an approximately 28% risk of uterine dehiscence or rupture.
Our group has worked on developing a minimally-invasive technique (so-called ‘keyhole surgery’) for the antenatal treatment of MMC, translating an experience of more than 10 years in the animal model to a viable clinical application. The technique developed by our group in collaboration with colleagues in Brazil does not require does not require hysterotomy (uterine incision). Rather, small instruments are placed into the womb through tiny incisions, and with the use of partial CO2 insufflation, the open spina bifida is repaired. This approach minimizes the risks of the surgery for the mother, while preserving the potential benefits of the in utero repair for the fetus.
The following management options will be offered to all eligible patients.
Who is a candidate for fetoscopic surgical treatment?
Details of the procedure
We offer two fetoscopic approaches to correcting the open spina bifida defect, both of which require general anesthesia and a 2-day inpatient stay:
Patients will remain in the hospital for about 2 days after surgery. Patients will then be sent home and asked to maintain minimal physical activity. This entails remaining at home for the duration of the pregnancy, except for doctor visits. Patients will have alternate follow-up visits between our office and their referring maternal-fetal medicine doctor every 1-2 weeks. Patients will also have a follow-up fetal MRI about 4 weeks after surgery. Patients may be given the option of a vaginal delivery, based on obstetric indications. Postnatal testing will be performed at 6, 12, 24, 30, 48, and 60 months of age.
Our group specializes in the assessment, counseling and management of patients with high-risk pregnancies in Florida.