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Spine | Spina Bifida

Spina Bifida (or Neural Tube Defect) is a structural defect of a baby’s central nervous system that occurs while a fetus is still inside the womb. This results in an opening in the fetus’ spinal column that exposes the spinal cord and the surrounding tissues. While this condition is not life-threatening, it can lead to children being born with significant disabilities. The most common type is a myelomeningocele (MMC) (an open neural tube defect), and, in selected cases, this can be repaired before the baby is born.

Essential Information

  • Myelomeningocele, or an open neural tube defect (NTD), is the most severe form of spina bifida, and occurs when an opening in the spine allows the spinal cord to be exposed.
  • This is caused by a failure of the spinal column to close early during fetal development.
  • Spina bifida is most often found during the routine anatomical ultrasound at 18-22 weeks gestation.
  • Myelomeningoceles are surgically treated after the baby is born but in some cases, surgeons may be able to repair this while the baby is still in the mother’s womb.

Overview

Myelomeningocele is a form of spina bifida, which affects approximately 120-150 babies in Canada each year. It is a result of the spinal column failing to close early during fetal development, causing permanent damage to the baby’s spinal cord and nervous system. The spinal cord and the nerves that surround are exposed through the open vertebrae of the spine.

Babies with myelomeningocele may have varying degrees of disability affecting their lower limbs and their bladder or bowel function. The degree of disability depends largely on the location of the spinal defect (with more disability seen with higher defects). Many individuals will require mobility supports such as leg braces, crutches or wheelchairs. More than 70% of children with myelomeningocele will require a shunt to be placed to relieve the pressure that builds up as a result of the accumulation of fluid around the brain (called hydrocephalus). This ventriculoperitoneal (VP) shunt, must remain in place for an individual’s entire life, and may occasionally become blocked, causing further complications and need to be replaced. Some affected children may have negative developmental and cognitive outcomes. One-third of adults with myelomeningocele require substantial lifelong daily support.

Treatment

Treatment of spina bifida is available both before and after birth. The timing and choice of procedure depends on a number of important criteria, including gestational age at diagnosis, severity of the condition and the mother’s general health. Treatment of defects in-utero involves closing the spinal defect to prevent further spinal cord damage and may reverse the swelling on the brain.

The Management of Myelomeningocele Study (MOMS), a groundbreaking trial published in the New England Journal of Medicine in 2011, showed that, in babies who underwent the in-utero procedure:

  • Brain malformations were reversed by one-third
  • The need for walking aids or a wheelchair was halved
  • The need for brain shunts was reduced by half

As a result, the Society of Obstetrics and Gynaecologists of Canada (SOGC) now requires that any pregnant woman whose fetus has been diagnosed with an open NTD be counselled about this treatment option.

In Canada, prenatal surgery is performed exclusively at the Ontario Fetal Centre.

Referral Information (for physicians)

Inclusion criteria

  • Open fetal spina bifida with upper level of the bony defect between T1 and S1
  • Chiari II malformation.

Exclusion criteria

  • Associated genetic anomalies or major anatomic anomalies.
  • Significant maternal comorbidities precluding safe surgery or anesthesia
  • Maternal BMI >40 kg/m.
  • Abnormal placentation.
  • Cervix <20mm or history of spontaneous preterm birth.
  • History of classical uterine incision or hysterotomy
  • Severe fetal kyphosis (>30°).

Practically

  • Early referral is necessary to allow for comprehensive work-up, multidisciplinary counselling and planning.
  • Surgery is performed between 23 and 25 weeks gestation.
  • Normal karyotype or microarray results are required prior to surgery.
  • Fetal MRI and echocardiography will be organized at SickKids.
  • After fetal myelomeningocele (fMMC) surgery, patients will remain in the hospital for at least one week.
  • After discharge, patients will be required to stay within one hour of Mount Sinai for the first 3-4 weeks after surgery but will then be referred back to their local centre familiar with the management of spina bifida postnatally, for further ongoing care and delivery.
  • Local patients will be followed and delivered at Mount Sinai Hospital.