This article discusses in detail the causes of neural tube defects, their treatment, and ways to minimize neural tube defects.
Spina bifida is a condition resulting from the malformation of the brain, skull, spinal cord, and spine to varying degrees that occurs within the first month after conception (pregnancy).
The embryonic tissues, which will later specialize to become the central nervous system (brain and spinal cord), the skull, and the spine, start out as a flat plate that rolls into a tube (neural tube). Defects in the neural tube may be due to:
Genetic inheritance from the parents.
Malnutrition, especially the deficiency of the B vitamin, folic acid.
These have been implicated as the cause of disruption of the normal formation process leading to an incomplete neural tube.
Defects in the neural tube can cause the brain to form outside the skull - Encephalocele.
It may lead to abnormal structure of the brain and skull leading to compression of the lower brain - Arnold-Chiari II malformation.
It may lead to abnormal structure of the cerebrospinal fluid circulation causing ventricular enlargement - Hydrocephalus.
It may also lead to defects in the spine, and spinal cord - Defects in the spine and spinal cord can range from an asymptomatic opening in the lower lumbar spine (spina bifida occulta) to more severe forms, including defects in the bone and covering of the nerves or dura (meningocele) or most severe, a defect in the bone, dura, and an incompletely formed spinal cord exposed to the environment (myelomeningocele). The thin layer of tissue present over the spinal cord and cerebrospinal fluid containing space around it in meningocele and myelomeningocele usually ruptures, if left untreated, leading to meningitis (bacterial infection around the central nervous system) which can lead to more severe disability or death.
Usually, these defects are in the posterior midline.
Neural tube defects occur with an incidence of between 0.1 to 1 per thousand births in developed countries but are significantly higher in undeveloped countries. The intake of 400 micrograms of Folic acid through the daily food intake of women of childbearing age regularly before they become pregnant substantially reduces but does not eliminate the possibility of occurrence.
Surgery for meningocele and myelomeningocele closes the potential for exposure of the spinal cord to the environment and usually protects it from further damage. Unfortunately, because the nerves are not well-formed, permanent disability and dysfunction, including loss of bladder, bowel, and sexual function as well as significant weakness or paralysis of at least the lower leg and foot, will still occur in the case of myelomeningocele. Despite this impairment, many children can learn to ambulate with bracing and crutch or cane devices.
The obstruction of cerebrospinal fluid flow (hydrocephalus) leads to increasing pressure on the brain, which lowers the blood supply to the neurons (nerve cells) and directly impairs their development. The process often accelerates after surgery for the myelomeningocele because its escape outside the body, which can lead to infection, is prevented. In the first two years of life, the head may abnormally enlarge (macrocephaly) as the plates that form the skull are not yet fused. Sometimes the hydrocephalus delays its progression until the child is older and skull plates have already closed, leading to the rapid onset of blindness, confusion, coma, and then death.
It is now well known that surgery for hydrocephalus in this situation results in most children functioning within the realm of normal intelligence, while no treatment in the face of progressive hydrocephalus certainly will result in permanent loss of intellectual function, coordination, vision, and even death. The most common treatment for hydrocephalus is the placement of a ventriculoperitoneal shunt (a tube and valve system that controls pressure or flow) which creates a detour of the cerebrospinal fluid from the brain to the peritoneal space (the space between the abdominal organs), where it is absorbed.
Newer alternatives involve placing a surgical telescope in the brain and attempting to open a channel to restore flow which may also include destroying the choroid plexus (tissue that produces the cerebrospinal fluid). The advantage of these newer procedures over traditional shunt surgery is controversial. Those who do undergo this type of procedure may not respond and still require a ventriculoperitoneal shunt. Unfortunately, ventriculoperitoneal shunts may suddenly stop functioning or become infected, needing repeat surgery. For reasons not always clear, a subset of children ends up having multiple operations, especially in the first few years of life.
Children with myelomeningocele can develop choking and upper extremity weakness or spasticity (stiffness caused by abnormal spasm of the muscles) from an Arnold-Chiari malformation. This may require removing the skull and sometimes the posterior part of the upper cervical vertebrae to remove pressure on the brain.
Occasionally at or near adolescence, a child with a history of myelomeningocele surgery will start to lose what lower extremity function they previously had. It is theorized that tethering of the spinal cord (restriction of the movement of the spinal cord up the spinal canal, which normally occurs with growth) causes mechanical disruption and/or decreased blood supply, leading to further dysfunction.
This can be difficult to assess as MRI (magnetic resonance imaging), which is used to evaluate the spinal cord, most often shows the spinal cord to be below its normal position and be tethered even in those with stable function.
Sometimes abnormal curvatures of the spine from the defects and muscle weakness threaten respiratory function or nerve function and require reconstructive spine surgery.
The treatment of tethered cord syndrome for a child with a history of myelomeningocele surgery can be a difficult decision. Often, anxious parents feel the desperation in wanting more function and may give a misleading history of loss of function. Some have advocated this type of surgery as a way to restore control of bladder or bowel function. Still, this loss of function is due to the original incomplete formation of the nerves rather than a later tethering in most cases.
In the past, surgery was often delayed for some time for spina bifida and the associated hydrocephalus with the idea that these children would be sentenced to live poor-quality lives. But this has been proven wrong. Today, most experts advocate surgery as early as possible to reduce the risk of infection and further injury. While the child is in the mother’s womb, attempts at the surgery are made in a few centers, but the benefit of this procedure which puts both mother and child at risk over early intervention after birth, is not yet clear.
Occulta, closed neural tube defects, meningocele, and myelomeningocele are the different types of spina bifida.
A child with spina bifida can walk with or without assistance like crutches, walkers, braces, or wheelchairs. A wheelchair is the mode of support in highly affected persons as their legs are paralyzed.
Though the etiology behind spina bifida is not known, it is probably reported due to gestational folate deficiency. It can also occur due to genetic or environmental factors.
Spina bifida cannot be cured entirely. Instead, it can be managed and prevented from complications. Depending on the stage and severity of the defect, treatment involves surgery, medications, and physiotherapy.
Spina bifida affects the sexual health of the person, but she is fertile and is fit to conceive and give a full-term birth.
Spina bifida in adults generally produces back pain and pain at the back of the legs. It is common in persons with spina bifida occulta, although it can be asymptomatic at times.
Spina bifida can be limited by starting folic acid supplements at the very early stage of pregnancy. Even more, it is advisable to begin it by at least 12 weeks before conception.
Infants with spina bifida develop hydrocephalus in which there is increased fluid encompassing the brain. Thereby, ventricles of the brain are filled with water and result in brain swelling.
Babies are more prone to spina bifida if the conceiving mothers have obesity, diabetes, and a history of miscarriage. Also, teenage mothers and those conceiving their first child have a higher risk.
Spina bifida causes disabilities that include improper growth, deformities of the muscle and skeleton, nervous problems, and intellectual inability.
Children with spina bifida find it challenging to carry out their day-to-day activities, urinary and bowel abstinence, and shape their independent future.
Effects of spina bifida include learning troubles like lack of concentration, memory, planning abilities, hand-eye coordination, motive.
Spina bifida happens in the early weeks of pregnancy, even before the woman finds out she is pregnant. It is detected in the ultrasound scan taken before the 18th week.
Regular follow-up, adequate care, and observation are needed in children diagnosed with spina bifida. Growth evaluation, the necessity for vaccinations and medical conditions, and supportive medical care are essential.
Fluids in the head contain extraneous proteins that damage the mesodermal organs like the heart, causing heart problems.
Last reviewed at:
21 Dec 2021 - 4 min read
Query: Hi doctor, I have pain in the lower back when I lay on a sofa or bed. When I stand, I have the pain in my back. This symptom appears only in the evening. It never happens in the morning or afternoon. I have taken X-ray and analytics. The results are: SV 1 spina bifida. There is a mild tilt of t... Read Full »
Query: Hello doctor, Do people who have spina bifida and have urinary and bowel incontinence also have fertility issues? Read Full »
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