Spina Bifida

The spinal cord is a tube-like structure made of nerves and nerve tissue that extends from the brain to the tailbone. It's surrounded and protected by a bony canal called the spine. In normal development, the spine closes completely around the spinal cord.

Spina bifida occurs when part of the spine, usually lower in the back, fails to close and leaves the spinal nerves exposed, which can result in mild defects or serious neurological problems.

Common Spina Bifida Conditions

Spina Bifida Occulta

Spina bifida occulta is the mildest form, in which the spinal cord remains covered by the skin of the fetus's back. Because the nerves have some protection from damage, babies who are born with this variety typically do not have problems at birth. Signs of spina bifida occulta may be visible over the location of the spine defect, and may include a tuft of hair, collection of fat, birthmark or small dimple, or skin discoloration.

Meningocele

Meningocele is a more severe form of spina bifida, in which the thin membranes (meninges) around the spinal cord protrude through a gap in the skin. The spinal cord is not fully exposed but is more vulnerable. Meningocele is the rarest form of spina bifida and often requires repair at birth to remove the membranes without damaging the nerves.

Myelomeningocele

The most severe form--and what the term “spina bifida” most often refers to -- is myelomeningocele (MMC), in which the spinal cord is completely exposed. MMC is frequently associated with nerve malfunction, which varies in severity based on the location of the defect along the spine: the higher in the back, the more nerves and muscles are involved, the more likely the baby will have neurological problems at birth. These may include muscle weakness (sometimes paralysis) and poor bowel and bladder control.

Myeloschisis

Myeloschisis is a severe form of a neural tube defect where the open neural tube appears as a flattened, plate-like mass of nervous tissue with no overlying membrane.  

How Common Is Spina Bifida?

Spina bifida occurs once in every 1,000 births, with varying severity. MMC is the most common form. According to the Centers for Disease Control and Prevention (CDC), each year about 1,645 babies are born with spina bifida.

How Is Spina Bifida Diagnosed?

The brain and spinal cord are surrounded by cerebrospinal fluid (CSF). In spina bifida, CSF leaks into the amniotic fluid through the opening in the spine. This increases the concentration of fetal proteins in the amniotic fluid, especially alpha-fetoprotein (AFP). High levels of AFP can be detected through amniocentesis, a common procedure in which a fine needle is inserted through the mother's abdominal wall and uterus to extract a small amount of amniotic fluid.

AFP eventually enters the mother's blood, where it can also be detected. Elevated levels of the protein (known as maternal serum alpha-fetoprotein) can suggest the presence of spina bifida, but can also indicate other fetal conditions. When a pregnant woman’s AFP level is elevated, she will be referred for an ultrasound to help diagnose spina bifida or other causes of the increased AFP levels. 

If spina bifida is suspected on ultrasound, magnetic resonance imaging (MRI) may be ordered to confirm the findings and help determine severity. MRI is painless and free of radiation, and does not affect the developing fetus.

What Can Spina Bifida Do to a Fetus Before Birth?

Recent research shows that prolonged exposure of the spinal cord and nerves to direct trauma and amniotic fluid may be toxic and increase damage to the spinal cord.

Additionally, babies with severe forms of spina bifida often suffer from hydrocephalus (“water on the brain”), in which an excess of CSF causes the brain to swell. Typically, this fluid must be drained at birth through the placement of a fine tube (shunt).

If there is too much CSF, the brainstem and cerebellum (the parts of the brain that control motor and sensory function) may shift or sag, known as a "Chiari-II" malformation. This can have fatal or near-fatal consequences for the fetus or newborn, including paralysis.

Spina Bifida 1

Deformity of the skull in spina bifida: lemon-shaped, instead of smooth oval.

Spina Bifida 2

Spina bifida (arrow) at the lower end of the spinal cord.

How Can Spina Bifida Be Treated Before Birth?

Fetal surgery to treat spina bifida was not available until recently and our program is the first in the region to offer it. In 2011, a study published in the New England Journal of Medicine showed that in most cases, fetal surgery was able to stop CSF from leaking and correct the Chiari-II malformation[1]. The percentage of affected toddlers walking without assistance at age two and a half was 42 percent when treated with fetal surgery, compared with 21 percent for those treated after birth. The study also showed that fetal surgery reduces the chances of requiring a shunt to correct hydrocephalus.

While the mother is under general anesthesia, an incision is made through the abdominal wall and uterus, exposing the fetus and revealing the spina bifida. The opening in the spine is closed using microsurgical techniques and the fetus is returned to the uterus for the remainder of the pregnancy.

Not all patients qualify for, or would benefit from, this treatment. The operation must be performed early enough in pregnancy (typically around 25 to 26 weeks) to be truly effective. The most common complication for the fetus is prematurity: any major surgical intervention on the uterus and the fetus increases the risk of rupturing the membranes and thereby early delivery, sometimes very prematurely. Premature infants are known to be at a greater risk of respiratory, neurological and other complications. Before fetal surgery is recommended, detailed evaluation of the condition and multiple consultations are needed.

What If I Would Like to Consider Fetal Surgery?

After the diagnosis of spina bifida has been made, you will have a discussion with a maternal fetal medicine specialist on the options of treatment, including fetal surgery. A referral will be made to the Fetal Treatment Program, where findings will be reviewed to see if the patient (both mother and fetus) qualify for fetal surgery. 

Fetal surgery may be offered in the following circumstances:

  • Myelomeningocele (including myeloschisis) defect located between the lower thoracic (chest) area of the spine and the sacrum (area above the tailbone)
  • Chiari-II malformation diagnosed by MRI and fetal ultrasound
  • Normal fetal karyotype (size, shape and number of chromosomes) by amniocentesis
  • Gestational age at referral between 19 and 25-6/7 weeks (5 to 7 months)
  • Age of the mother is at least 18 years

Unfortunately, fetal surgery may not be safe in the following circumstances:

  • Multiple gestation (twins, triplets, etc.)
  • Contraindications to surgery or anesthesia for the mother such as severe asthma, cardiac disease, refusal to accept a blood transfusion
  • If the mother has been diagnosed with severe hypertension (high blood pressure)
  • Insulin-dependent, pregestational diabetes (high blood sugar present even before pregnancy)
  • Infectious diseases such as HIV, Hepatitis B or C in the mother
  • Severe obesity – BMI greater than 40 (Grade 3 obesity), or greater than 35 with obesity-related morbidity (e.g. hypertension, diabetes). Maternal BMI of 35 to 40 will be evaluated on a case-by-case basis
  • Fetal kyphosis (curve of the spine) greater than, or equal to, 30º at the level of the defect
  • Other fetal problems not related to the Spina Bifida such as a heart defect or intracranial hemorrhage (bleeding within the brain)
  • Shortened cervix (opening to the uterus) less than 20 mm or dilated cervix
  • Early labor in the current pregnancy
  • History of early delivery (before 37 weeks). This does not include induction of labor or delivery prior to 37 weeks if done for a fetal or maternal illness. A history of stillbirth will require further review
  • Placenta previa or abruption (location of the placenta is over the area of the uterus called the cervix or a part of the placenta has prematurely separated from the uterus)- a history of vaginal bleeding in this pregnancy will have to be evaluated before fetal surgery could be offered
  • Problems with the uterus such as large or multiple fibroids, abnormalities in the uterus such as a bicornuate or unicornuate uterus, uterine septum and double uterus. Any prior uterine surgery such as classical Cesarean section, myomectomy (removal of fibroids) or previous open fetal surgery
  • Instances where the mother’s blood fights against certain proteins in the blood. These conditions are known as Rh isoimmunization, Kell sensitization or history of Neonatal Alloimmune Thrombocytopenia
  • Deemed not eligible due to psychosocial criteria after evaluation with a psychologist

If the mother and fetus both qualify for fetal surgery, the mother will then be scheduled for multiple consultations to discuss the pros and cons of fetal surgery. She will meet with the high-risk obstetrician (maternal-fetal medicine specialist), fetal surgeons, pediatric neurosurgeon(s), an anesthesiologist who specializes in giving anesthesia to pregnant women, and a social worker. All of these consultations help educate the mother and help her make important decisions regarding her pregnancy and whether fetal surgery is the right option for her.

What If I Choose To Have Fetal Surgery?

If you qualify for fetal surgery and decide to move forward, you will be admitted to the hospital at around 25 weeks for surgery. Prior to being admitted you will receive two shots of a medication called betamethasone to help your baby’s lungs mature in case the baby is born soon after fetal surgery. You will then be admitted to Women and Infants Hospital where you will have blood work drawn on the day of surgery.

Your actual surgical procedure will be performed at Rhode Island Hospital. Your team will consist of physicians and nurses from both Women and Infants Hospital (maternal fetal medicine and neonatology) and Rhode Island Hospital/Hasbro Children’s Hospital (pediatric surgery, pediatric neurosurgery and anesthesia) will perform the operation. The operation lasts one to two hours and you will recover in the post-anesthesia care unit (PACU, or recovery room) for several hours. You will then be transferred back to Women and Infants Hospital, where you will stay on the labor and delivery (L&D) unit for observation. Because this type of surgery is very invasive, you must be monitored closely for signs of labor, your water breaking, and fetal distress. Once you are stabilized on the L&D unit, you will be transferred to the Antepartum Care Unit, where you will stay until it is time to go home. You can expect to be in the hospital for about four days.

All patients must be on medication to help stop contractions until 36 weeks of pregnancy. You will need to be on modified bedrest for at least two weeks after surgery. Return to normal activity will depend on whether you develop contractions with increased activity. You will need to be out of work for the remainder of your pregnancy. After surgery, you should be cared for by a high-risk pregnancy service that will allow standardized postoperative care, ultrasound evaluation and delivery. If you are local, that care will be provided by the Maternal Fetal Medicine Department at Women and Infants Hospital and ultrasound surveillance will be provided by the Prenatal Diagnosis Center. You will need weekly follow up visits to assess any pain you are having, wound healing, signs of rupture of the membranes, and premature labor. Weekly ultrasounds to assess the amount of amniotic fluid, whether the membranes are intact, and fetal assessment will be scheduled. Monthly measurements of the baby’s head and growth will also be completed. 

You will be asked to stay in close contact with our nurse coordinator with any signs and symptoms of labor, membrane rupture, decreased fetal movement and other signs that the baby or you are having complications.  There may be times that you have to be admitted to the hospital for the duration of your pregnancy or even early delivery. 

What If I Choose Not To Have Fetal Surgery?

You should continue your routine prenatal care with your obstetrician or have your care transferred to a high-risk obstetrician for specialized care for both you and your fetus. You should discuss with your obstetrician if your care needs to be transferred to a high-risk obstetrician. Your fetus should be followed by monthly ultrasounds to monitor your baby’s growth, and for signs of worsening hydrocephalus. 

What Are My Delivery Options?

If fetal surgery has been performed, the uterus is more fragile and Cesarean section is mandatory. If you opt to have the spina bifida repaired after birth, route of delivery (either vaginal or C-section) will be determined by your obstetrician. 

A newborn with spina bifida is at risk for severe infections and other complications, so it is recommended that mothers deliver in a center with immediate access to a specialized neonatal intensive care unit and immediate availability of pediatric neurosurgeons and pediatric plastic surgeons.

What Will Happen at Birth?

After the birth, the baby with spina bifida will be monitored very closely for any neurological, respiratory or infectious problems. If the mother did not undergo a fetal surgery to repair the spina bifida, the exposed spinal cord will be protected with a sterile bandage to avoid further injury. Tests will be performed to determine which nerves are affected by the spina bifida.

A consultation with a pediatric neurosurgeon and pediatric plastic surgeon (as well as other specialists, such as urologists) will be obtained rapidly, and a procedure to repair the defect typically occurs in the first few days of life. If there is associated hydrocephalus, a shunt to drain the brain of excess CSF may be placed as well.

If the mother has had fetal surgery for the baby’s spina bifida, the baby will be admitted to the newborn intensive care unit (NICU) for observation, assessment of the incision, and evaluation for associated complications of spina bifida (hydrocephalus, Chiari-II malformation, clubfoot, etc.).

What Is the Long-Term Outcome for Spina Bifida Patients?

The long-term outcome for babies with spina bifida varies based on the location of the defect (the higher on the spine, the worse the chances of normal lower extremity function) and the presence of other complications.

Hydrocephalus is the most common associated condition; however, as long as the excess fluid in the brain is successfully drained, children can develop normally. Sometimes, the shunts malfunction or become infected, which requires further treatment and operations. A recent study of mothers who participated in the Management of Myelomeningocele study (MOMS) found enduring effects of prenatal surgery for myelomeningocele with improved motor functioning and a reduction in Chiari-II malformations and hydrocephalus, as well as better gross and fine motor functioning and quality of life, with reduced negative impacts on families[2].

Spina bifida is not usually deadly (although there is an increased chance of sudden death within the first two years). Neurological and motor function (particularly of the legs) as well as bowel and bladder function can be affected to varying degrees. Children and adults with spina bifida are at a higher risk of serious infections, including urinary and kidney infections.

References:

  1. "The Management of Myelomeningocele Study," sponsored by the National Institutes of Health.
  2. Houtrow AJ, Thom EA, Fletcher JM, et al. "Prenatal Repair of Myelomeningocele and School-age Functional Outcomes." Pediatrics. 2020;145(2):e20191544