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Myelomeningocele Repair

What is fetoscopic myelomeningocele repair?

Myelomeningocele is the most severe form of spina bifida and it occurs when nerves from the spinal cord protrude through the opening in the spine and become exposed to the outside. Traditional fetal myelomeningocele repair is performed through an incision of the uterus. This type of approach to the fetus requires cesarean delivery of all future pregnancies and is associated with an approximately 10% risk of partial or complete opening of the uterine scar at any time following surgery. Because of the significant maternal risks of open fetal surgery, a less invasive form of uterine access using a small camera (fetoscopy) has been developed.

The Johns Hopkins Center for Fetal Therapy is one of a few in the world that have successfully performed fetoscopic spina bifida repair. Mothers who meet inclusion criteria for fetal surgery have the option to participate in an FDA-monitored protocol for fetoscopic spina bifida repair (Clinical trials.gov ID NCT03090633). Following fetoscopic repair, women may deliver closer to their due date and have the option of vaginal delivery for the current and future pregnancies.

What are the benefits of prenatal myelomeningocele repair?

The primary treatment of a myelomeningocele consists of closure of the defect before birth – typically between 19 to 26 weeks’ gestation. The randomized trial of prenatal versus postnatal surgical repair (MOMS trial) established that closure of the neural tube defect by fetal surgery has significant benefits for the infant after birth. These include:

  • An over 50 percent reduction in the need to perform shunting treatment for hydrocephalus
  • Almost tenfold reduction in hindbrain herniation and Chiari 2 malformation at age 1
  • A better of level of function of the spinal cord
  • Doubling of the ability to walk without assistance

The MOMS trial established the role of fetal surgery for improving infant outcomes in patients with spina bifida.

Who is eligible for prenatal myelomeningocele repair?

Fetal myelomeningocele repair is offered only for singleton pregnancies that have an isolated spina bifida defect. This means there are no genetic abnormalities and no other structural anomalies. In addition, there are the following specific criteria:

  1. Severe Myelomeningocele
    • Upper lesion border between T1-S1
    • Chiari 2 malformation
    • Preserved hip and leg movement
  2. Absence of major maternal medical conditions
  3. Absence of obstetric risk factors
    • Prior preterm birth before 37 weeks
    • Short cervical length
    • Prior classical cesarean section or major uterine surgery
    • Abnormality of the uterus
  4. Absence of surgical risk factors
    • Prepregnancy body mass index >35 kg/m2
    • Unwillingness to accept blood transfusions

In preparation for fetal myelomeningocele repair, patients undergo a detailed assessment of the fetal anatomy by prenatal ultrasound and MRI imaging and review of the medical history at our center and get an opportunity to meet with the pediatric neurosurgeon and neonatologists. Once we confirm eligibility and patients elect to undergo fetal myelomeningocele repair, the procedure is scheduled between 19+0 to 25+6 weeks’ gestation. 

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