Myelomeningocele is a severe birth defect affecting the spine and spinal cord. It is the most serious form of spina bifida, a neural tube defect. This condition results from incomplete closure of the neural tube during early fetal development, leading to varying degrees of disability.
Understanding Myelomeningoceles and Their Causes
Myelomeningocele is an anatomical defect where the spinal cord and its protective coverings, the meninges, protrude through an opening in the backbone, often forming a fluid-filled sac on the baby’s back. This occurs when the neural tube, which forms the brain and spinal cord, does not fully close between day 17 and day 30 of gestation. The severity of symptoms depends on the defect’s location and size along the spine, with higher lesions leading to more severe impairments.
The cause of myelomeningocele is multifactorial, involving genetic predispositions and environmental influences. Insufficient folic acid (vitamin B9) intake before and during early pregnancy is a significant preventable risk factor. Other factors that increase risk include a family history of neural tube defects, certain anti-seizure medications, and uncontrolled diabetes in the pregnant individual.
Detecting Myelomeningoceles
Myelomeningoceles are often detected during pregnancy through prenatal screening. A common screening is the maternal serum alpha-fetoprotein (MSAFP) blood test, usually performed between 15 and 20 weeks of gestation. Elevated MSAFP levels can indicate a higher risk of neural tube defects, including myelomeningocele.
If initial blood screenings suggest a risk, a detailed prenatal ultrasound scan visualizes the fetal spine and brain. Ultrasound identifies the physical defect and associated brain anomalies, such as Chiari II malformation. When screenings are positive, amniocentesis may confirm the diagnosis.
After birth, myelomeningocele is visible as a sac on the baby’s back. Diagnosis is confirmed through physical examination and imaging tests. MRI or CT scans provide detailed images of the spinal cord and neural elements, assessing the defect’s extent and planning surgical intervention.
Treatment Approaches
Fetal surgery, or in utero repair, is an advanced option where the myelomeningocele is surgically closed while the baby is still in the womb, typically between 19 and 26 weeks of gestation. This procedure aims to reduce progressive damage to the spinal cord and nerves from amniotic fluid exposure. Benefits include a reduced need for a shunt to treat hydrocephalus and improved motor function.
Eligibility for fetal surgery is assessed by considering gestational age, lesion location and severity, and the health of both mother and fetus. Traditional open fetal surgery involves a uterine incision and carries maternal risks, such as increased likelihood of C-sections. Less invasive fetoscopic techniques use tiny incisions and may allow for vaginal delivery in future pregnancies.
Following birth, immediate surgical closure of the defect is performed within 24 to 72 hours. This postnatal surgery prevents infection of exposed neural tissue and further nerve damage. The goal is to restore nerve tissue to the spinal canal and close the defect.
Immediate post-operative care involves meticulous wound management to prevent infection and promote healing. Infants are positioned prone or side-lying to protect the surgical site. Monitoring for complications, especially hydrocephalus, is continuous, often involving daily head circumference measurements and regular head ultrasounds.
Managing Associated Conditions and Long-Term Care
Hydrocephalus, a buildup of cerebrospinal fluid in the brain, is a common complication affecting up to 90% of individuals with myelomeningocele. This condition is managed by surgically implanting a ventriculoperitoneal (VP) shunt, which drains excess fluid from the brain’s ventricles to the abdominal cavity. Shunts can be prone to complications like blockage or infection, requiring ongoing monitoring and revisions.
Bladder and bowel dysfunction are common challenges due to nerve damage affecting control. Management for neurogenic bladder often involves clean intermittent catheterization (CIC) to empty the bladder, along with medications. Bowel management programs include dietary adjustments, medications, and sometimes enemas.
Mobility challenges vary widely depending on the spinal defect’s level, ranging from muscle weakness to partial or complete leg paralysis. Physical therapy maximizes functional mobility through exercises, gait training, and assistive devices like braces, crutches, or wheelchairs. Occupational therapy assists with daily living activities, and ongoing monitoring addresses issues like pressure sores.
Individuals with myelomeningocele may experience other associated conditions. These include orthopedic issues like scoliosis, hip dislocations, and clubfoot, which may require intervention. Skin problems, such as pressure sores, are also common due to decreased sensation. Learning differences, attention problems, and difficulties with reading or math may arise, and some individuals may experience seizures.
Long-term care for individuals with myelomeningocele requires a multidisciplinary approach involving a team of specialists. This team includes neurosurgeons, urologists, orthopedists, physical therapists, and occupational therapists. This coordinated care addresses complex medical, developmental, and social needs throughout life, supporting optimal function and quality of life.
Prevention Strategies
Adequate folic acid intake before conception and during early pregnancy is the most effective prevention strategy for myelomeningocele. All individuals planning or who could become pregnant should take a daily supplement containing 0.4 to 0.8 milligrams (400 to 800 micrograms) of folic acid. This supplementation should begin at least one month before conception and continue through the first two to three months of pregnancy.
For individuals who have previously had a pregnancy affected by a neural tube defect, a higher daily dosage of folic acid, typically 4 milligrams, may be prescribed. Folate, the natural form of vitamin B9, is found in many foods. Foods rich in folate include dark green leafy vegetables, legumes, citrus fruits, asparagus, and fortified grains and cereals.