Open spina bifida, or myelomeningocele, is a birth defect that occurs when the bones in a baby’s spinal column do not properly close. The baby’s spinal cord extends through the bones and is attached to the skin, which may cause spinal cord damage. Most often, this developmental abnormality is found on the baby’s low back, but can occur anywhere along the spinal column. Symptoms related to open spina bifida vary from child to child.
Causes of a Myelomeningocele Spina Bifida
The exact cause of spina bifida is unknown, but many environmental and genetic factors are thought to play a role.
Although the precise mechanism of action is unknown, folate has been shown to decrease the incidence of open spina bifida in several population studies . In order for folate to be effective, the pregnant mother needs to consume this B vitamin (Folate 0.4 mg or 4oo mcg) prior to conception since the nervous system closes within the first few weeks of development. Fortunately, in the United States, both our cereal grains and corn maize supplies are now fortified with folic acid.
Of note, if a mother has a history of spina bifida or has had a prior pregnancy with an open neural tube defect, 4mgs of folate is recommended prior to conception.
Open neural tube defects may be diagnosed as early as 18-22 weeks into a pregnancy. An ultrasound examination or blood test can help to confirm the diagnosis. Open spina bifida may be suspected when there is an elevated maternal serum or amniotic fluid level of alpha-fetoprotein (AFP). Fetal magnetic resonance imaging (MRI) may be obtained to gain additional information about the fetus’ brain and spinal cord.
An open spinal defect may cause weakness in the infant’s lower extremities and/or bowel/bladder function due to the exposed neural tissue during in utero development. The higher the lesion on the baby’s back the more likely the infant will demonstrate weakness in their neurological/urological/orthopedic functioning. Patients with open spina bifida are managed by a multidisciplinary team of specialists to define a newborn’s function and monitor for any decline throughout childhood. This team consists of: pediatric neurosurgeons, pediatric urologists, pediatric orthopedic surgeons, physical medicine and rehabilitation specialists, nursing, social work, developmental pediatricians, and pediatric therapists.
During in utero development, open spina bifida allows escape of spinal fluid where the spinal cord is exposed. This egress of spinal fluid may lead to abnormalities in the development of the brain and spinal cord, known as the Chiari II malformation. All babies with open spina bifida have a Chiari II malformation, but not all children demonstrate symptoms related to this condition.
Many infants born with open spina bifida will have an enlargement in the spinal fluid cavities of the brain, known as the cerebral ventricles. Some children with myelomeningocele may develop progressive enlargement of the ventricles requiring either diversion of the fluid (known as a ventriculo-peritoneal shunt) or creation of an alternate brain pathway (known as an endoscopic third ventriculostomy, or ETV) for adequate fluid management. A pediatric neurosurgeon will monitor the infant with open spina bifida for progressive enlargement of the ventricles, or hydrocephalus.
After confirming the diagnosis of an open fetal spina bifida, the fetal team will discuss the long term implications of this diagnosis for the child as well as various treatment options. Both prenatal and postnatal closure of the open defect will be discussed and the mother will be informed if she is a candidate for prenatal closure consideration.
The Chicago Institute for Fetal Health is one of the only fetal centers in the country that offers a minimally invasive approach for spina bifida repair in utero. Babies who have the defect closed surgically before being born have been shown to have better long-term prognoses. View the video below for more information on one type of this surgery.
In a randomized trial (MOMS trial ref.), prenatal closure of the open myelomeningocele has been shown to decrease the need for permanent CSF diversion at 12 months in a fetus with ventricles less than 15 mm as well as improved lower extremity strength when assessed at 30 months. Prenatal surgery, however, carries significant risks for the mother and unborn child and must be carefully considered for each pregnancy.
For infants born with an open defect, closure of the back occurs within 1-3 days following birth. The newborn is then closely monitored for development of hydrocephalus or Chiari II symptoms. Baseline evaluations are completed to determine the infant’s neurological/urological/orthopedic function.
Long term all children born with open spina bifida are followed in Lurie Children’s Spina Bifida Center, which provides multidisciplinary, compassionate, and comprehensive care for children and adolescents with spina bifida. From prenatal consultation through young adulthood, a collaborative approach brings together a team of specialists who are dedicated to providing high quality care. Our renowned experts in neurosurgery, orthopedic surgery, and urology collaborate with teams from rehabilitation services, clinical nutrition, and family services to provide innovative and comprehensive clinical care for our patients and their families.
To schedule an appointment with The Chicago Institute for Fetal Health, call 1.866.FETAL24. To schedule an appointment in Spina Bifida Clinic or Tethered Cord Clinic, call 312.227.4220 and speak to Dani Gacek, Spina Bifida Administrative Coordinator.