What is spina bifida (myelomeningocele)?
Spina bifida is a birth defect that occurs when the bones in a baby’s spine do not fully form during early pregnancy. This happens between 20 and 28 days of gestation, often before a woman knows she is pregnant. This results in an opening on the back that leaves a section of the spinal cord and spinal nerves exposed. Usually, the exposed spinal cord and nerves are contained in a sac that is exposed to amniotic fluid. Continuous bathing of the fragile developing spinal cord in amniotic fluid over the course of gestation is thought to result in progressive neurologic injury.
Spina bifida occurs in about 3 to 4 babies in every 10,000 live births. We don’t know why spina bifida happens. Research suggests that getting enough folic acid before and during the first six weeks of pregnancy can help prevent it. When you find out you’re pregnant, your doctor will want to make sure you’re eating enough greens, nuts and fortified cereal to help reduce the chances of having a baby with spina bifida. You may also want to take folic acid supplements.
The types of spina bifida include:
- Spina bifida occulta. This is a mild form of spina bifida in which the spinal cord and the surrounding structures remain inside the baby, but the back bones in the lower back area fail to form normally. There may be a hairy patch, dimple, or birthmark over the area of the defect. Other times, there may be no abnormalities in the area.
- Meningocele. This is a moderate form of spina bifida in which a fluid-filled sac is visible outside of the back area. The sac does not contain the spinal cord or nerves.
- Myelomeningocele. This is the most serious and common form of the disease. With this form of spina bifida, a little bit of the baby’s spinal cord and nerves protrude through an opening in the spine into a flat disc or sac that’s visible on the back. The opening in the spinal cord also results in loss of the fluid surrounding the nervous system. This causes the brain to be positioned further down into the upper spinal column than normal, which is called a Chiari II malformation. When this happens, the normal flow of fluid out of the brain is obstructed, causing hydrocephalus, an excess of cerebrospinal fluid within the brain. After birth, most children with hydrocephalus need to have the extra fluid shunted out of the brain into the abdomen via a ventriculoperitoneal shunt.
Depending on the lesion’s location, myelomeningocele may cause bladder and bowel problems; sexual dysfunction; weakness and loss of sensation below the defect; orthopaedic malformations such as club foot or problems of the knees or hips; and inability to move the lower legs (paralysis). Generally, the higher the defect is located on the spine, the more severe the complications. Approximately 80 percent of defects are found in the lower back area. The remaining 20 percent of the defects are located in the back of the neck or upper back areas.
How is the condition diagnosed?
At about 15 weeks gestation, a blood test measuring the levels of alpha-fetoprotein can show the physician that there might be a problem. A routine ultrasound is can also detect the myelomeningocele, as well as the conditions that can result from it, such as hydrocephalus, the Chiari malformation, and any problems with the lower extremities. In all cases, we perform a fetal MRI to gain more detailed information and we perform a fetal echocardiogram to rule out any problems with the heart.
Severe spina bifida (myelomeningocele) will be obvious right after the baby is born. For example, your doctor will able to see a fluid-filled sac that pokes out from the baby’s back. For milder cases (spina bifida occulta), there might be a dimple or hairy patch of skin on the spinal column.
How is spina bifida treated?
After evaluation by our maternal-fetal medicine specialists, our nurse navigator will arrange for you to meet with members of our multidisciplinary team, including a genetic counselor, neonatologist, and pediatric neurosurgeon. The decision of whether prenatal or postnatal spina bifida treatment is appropriate is influenced by several considerations, including gestational age, the level of the myelomeningocele lesion on the spine, presence of the Chiari II malformation, and a number of important maternal health factors. Prenatal repair also requires a significant commitment on the part of the mother and her support person.
Our team helps each family fully understand the benefits and risks of spina bifida treatment so they can make the best decision for their unique situation. Our team also counsels and supports families who choose to terminate the pregnancy.
A cesarean delivery may be recommended to decrease the risk of damage to the spinal cord that may occur during a vaginal delivery. However, a safe vaginal delivery is often possible, especially with small lesions. Babies born with a meningocele or a myelomeningocele usually require care in the neonatal intensive care unit (NICU) for evaluation and for surgery to close the defect.
Treatment options depend on how severe the case is.
- Spina bifida occulta. This form of the condition does not need any surgical treatment, but you pediatrician will closely follow your baby’s development for signs of neurological impairment.
- Meningocele. Your baby will need surgery soon after birth, but not immediately. During this surgery, the pediatric neurosurgeon will put the meninges (the three membranes that surround your baby’s brain and spinal cord) back and seal up the hole in the vertebrae (back bone).
- Myelomeningocele. A few babies might qualify for prenatal surgery to repair the spinal defect. This surgery has risks, especially a higher likelihood of preterm birth, and is only performed at a few select centers in the United States. Our team will provide you with the necessary information to help you decide if you would like to be evaluated for prenatal surgery and coordinate your referral to a center. However, if you decide surgery is not right treatment plan for you, your baby have surgery after delivery within a day or two after birth. One of our pediatric neurosurgeons will perform the repair of the spinal defect.
With this surgery, the neurosurgeon places the nerves and spinal cord back into the vertebrae and repairs all of the layers of the spinal column, muscles and skin. Some surgeries take several hours to complete since there are multiple layers to repair. The baby will require a breathing tube during the surgery and for some time after, until the anesthesia wears off and he or she is breathing normally. Once the baby is awake from surgery, he or she can begin feeding. While waiting for feeding to start the baby will get nutrition through an IV. After surgery the baby may have restrictions on his or her positioning until the back begins to heal. You will be able to hold your baby, but positioning aids may be needed to support the baby and avoid disturbing the surgical site. Although, surgery can help protect the nerves and spinal cord from future infection, it cannot restore muscle function or sensation to a normal state.
- Hydrocephalus. About 90 percent of babies with myelomeningocele will develop this condition, sometimes referred to as “water on the brain.” Your doctors will want to drain this fluid shortly after birth, sometimes at the same time as the back repair and sometimes in a second surgery. This condition is corrected by placing a small tube in the ventricle (where the spinal fluid is stored in the brain), and shunting the fluid to the baby’s abdomen. Even if your baby doesn’t show signs of this condition at birth, it might develop at a later time. Your neonatologist, neurosurgeon and pediatrician will monitor your baby’s progress. To monitor the amount of hydrocephalus frequent ultrasounds will be obtained.
How will spina bifida affect my baby during and after surgery?
According to the Spina Bifida Association, there is some good news about babies with spina bifida:
- 90 percent of babies with spina bifida live well into adulthood.
- 80 percent have normal intelligence.
- 75 percent participate in modified sports activities.
The majority of children can manage their bladder and bowel output by doing self- catheterization (using a tube to drain urine from the bladder).
The outcome for your baby depends on a few factors. These include:
- Where the nerves were damaged on the spine – if the nerves were damaged in the lower part of the spine, this will increase your baby’s odds of not using a wheelchair or braces when he or she gets older
- If your baby was born with any other brain defects
- The treatment option for your baby
- The size of the lesion
Dayton Children’s Hospital provides comprehensive long-term follow-up clinic for children with spina bifida. This team includes multiple specialists and therapist to help you manage your child’s care and to monitor progress. Children are seen in this clinic from the time of repair through adolescence. Our team works closely with each family and primary care pediatrician to help you access appropriate community services.
Photo credit: Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities.