If a neural tube defect is detected during pregnancy in an ultrasound examination, it comes as a great shock to the parents-to-be. Depending on the severity of this malformation, the baby may not be able to survive or may be born with disabilities, some of them severe. In Germany, the risk of giving birth to a child with a neural tube defect is about 1 in 1000. To prevent this from happening in the first place, every woman of childbearing age should take appropriate precautions and consume sufficient folic acid in good time.
What is a neural tube defect?
A neural tube defect results from a developmental abnormality between about day 18 and day 28 after conception. During this time, the precursor to the nervous system, the neural plate, forms in the embryo. Initially, it is an elongated indentation in an area that later develops into the child’s back. As cell division progresses, this indentation closes by day 28 after the egg and sperm combine to form the neural tube, which gives rise to the spinal cord, spine, brain and skull. In the case of a neural tube defect, it does not close completely. This defect can occur in one or more places of the future spinal column and can vary in size. The consequence is a so-called “open back”, a spina bifida or anencephaly. Anencephaly translates as “without a brain“. Babies born with this severe form of neural tube defect are missing large parts of the brain and the top of the skull. These children are not viable. They are either stillborn or die shortly after birth.
Causes
A neural tube defect can have many causes. They may be genetic, due to chromosomal abnormalities, or caused by metabolic influences and harmful substances. A neural tube defect can also be triggered by a viral infection, for example with rubella, high fever or exposure to radiation through X-rays or a CT scan in early pregnancy. Furthermore, women who have to take antiepileptic drugs and also women with type 1 diabetes are at risk, especially if they are poorly controlled. Folic acid deficiency is another possible cause.
Symptoms, complaints, and signs
The symptoms of spina bifida depend on the area of the spine that is damaged and whether the spinal cord bulges outward through the gap created in the neural tube. In the mild form, spina bifida occulta, affected individuals are often unaware of their deformity unless a doctor detects it during an X-ray examination. Such a neural tube defect causes non-specific complaints such as back pain, skin changes in the area of the spinal defect, or weakness of the bladder sphincter. However, if the spinal cord or meninges are affected by the neural tube defect and the nerve tissue is damaged, the spectrum of complaints ranges from minor movement disorders to paraplegia. Other symptoms may include scoliosis (a curvature of the spine), muscle atrophy and joint deformities. Spina bifida rarely causes brain damage. However, some infants develop hydrocephalus, which is when the back end of the cerebellum protrudes into the spinal canal. This does not cause brain damage, but it can affect the circulation of cerebrospinal fluid. Most affected children have normal intelligence, however.
Diagnosis and course of the disease
A neural tube defect is usually detected by ultrasound examination. Large defects in the neural tube are visible as early as twelve weeks’ gestation. Less pronounced vertebral abnormalities can be detected between sixteen and twenty weeks. However, if the back of the fetus is difficult to assess or if there is a high risk, an amniocentesis may also be necessary. Less conclusive is the triple test (blood test) in the fourth month of pregnancy.
Complications
Whether complications arise from a neural tube defect depends on where the defect is located. For example, a particularly extreme form of neural tube malformation, anencephaly, is incompatible with life because large portions of the brain do not even form in this case. The newborn dies after a few weeks. The second form of neural tube defect, spina bifida, shows different appearances with different effects.Thus, the defect may go completely unnoticed if the spinal cord is not involved. If the spinal cord is involved and the defect is open with exposure of the neural tissue, the neural tube must be surgically closed immediately after birth or even before. Otherwise, there is a risk of severe infection, which can be fatal. Even afterwards, most patients need lifelong care. In severe cases, sufferers are at risk of paraplegia. Some patients suffer from urinary and fecal incontinence. Sometimes both the spinal cord and the brain are affected. In this case, the child’s mental development may also be negatively affected. However, it is not possible to make precise statements about the prognosis in this regard. In most cases, the children develop normally intelligently. Often, there is also a neurogenic bladder, which requires constant medical treatment, otherwise the loss of kidney function could develop as a complication.
When should you go to the doctor?
Neural tube defects occur in the closely monitored first trimester of pregnancy. That is why it is very important so early that the woman regularly attends the scheduled preventive examinations. In this context, a neural tube defect in the fetus can be detected and treated. In this way, the later consequences after birth can at best be contained to such an extent that the baby can lead a largely normal life. If a neural tube defect is already so severe that the child would be born with disabilities, the woman can still decide now to have a late abortion. Screening during pregnancy is also important to detect any nutritional deficiencies and other risk factors for a neural tube defect and to intervene in time. If a baby is born with a neural tube defect, the pediatrician is already required immediately after birth and must determine whether the ultrasound images correspond to the actual state of health of the newborn. Many newborns need surgery immediately after birth, depending on the type and severity of the neural tube defect, because the earlier treatment takes place, the better a congenital neural tube defect can be treated. Any surgical scars also heal quite well at such an early age and can become almost invisible later in life. In this way, the newborn can also still have a normal life.
Treatment and therapy
American scientists began closing a neural tube defect prenatally 20 years ago. To reach the baby, this required opening the abdomen and uterus through larger incisions. In the meantime, a minimally invasive surgical method has been developed to close spina bifida while the baby is still in the womb – German Center for Fetal Surgery and Minimally Invasive Therapy (DZFT). This prenatal intervention has a beneficial effect on the function of the lower extremities as well as on the bladder and rectum. It can also limit the development of hydrocephalus. The best conditions for this intervention are in the early 20s weeks of pregnancy. If babies are born with an open back, then germs can invade and cause further nerve damage. Therefore, the open spinal cord structures must be surgically closed in the first one to two days after birth. If hydrocephalus is also diagnosed, an additional artificial drain is created for the excess cerebrospinal fluid. Regular bladder and bowel emptying must also be ensured if paralysis is present here. For affected children, a high-fiber diet and sufficient fluid intake are important to keep the stool consistency soft. The goal of subsequent therapy will be to allow children to have a great deal of independence and mobility. A pediatrician and adolescent doctor knows the different specialties that can help with this. He or she can coordinate and provide information sharing.
Outlook and prognosis
For the prognosis in neural tube defects, the resulting disease is important. If the defect manifests itself in the form of spina bifida occulta, affected individuals usually do not notice the malformation and it is possible to lead a normal life. The situation is different in the case of myelomeningocele.This is a serious disease that can cause significant problems in childhood and adolescence as well as in adult life. Infections, urinary tract and kidney problems, paralysis, and hydrocephalus (water on the brain) are common symptoms of this disease. Often, affected individuals also show significant difficulties on a social level; mental retardation and psychiatric problems are not uncommon. Very severe cases also show more extensive damage, which extremely reduces the survivability of the affected children. However, even with myelomeningocele, most affected individuals can lead a good life and integrate in both social and professional life. Treatment of a neural tube defect always involves surgery. Depending on the type and severity, this usually takes place immediately after birth. This is particularly important for the prognosis, because the earlier the treatment is performed, the better the prospects for later life.
Prevention
The best preventive measure against a neural tube defect is an adequate supply of folic acid at the latest at the beginning of pregnancy, and even better already when a desire to have a child manifests itself. A developing baby needs this vitamin for its cells, tissues and organs. It plays an important role in the development of the brain and spinal cord. An adequate folic acid supply minimizes the risk of a neural tube defect by half.
Here’s what you can do yourself
When prospective parents learn that their child has a neural tube defect, it comes as a shock at first. This is especially true if the defect is severe and, in all likelihood, the child will not survive. Other forms of neural tube defects may be surgically corrected during pregnancy (prenatal) or a few days after birth. Children with a neural tube defect are usually dependent on help throughout their lives. This makes it very difficult for the parents of the affected children. Depending on the individual diagnosis of the defect, psychotherapeutic support or various self-help groups can help. Help for self-help is offered on the one hand by the Anencephaly-Infoseite (www.anencephaly.info), which provides its information in several languages. Another Internet address is that of the Arbeitsgemeinschaft Spina Bifida und Hydrocephalus e. V., a self-help group that has been in existence since 1966 (www.asbh.de). In the worst of all cases, help is available from the Bundesverband Verwaiste Eltern und trauernde Geschwister in Deutschland e.V. (www.veid.de). Generally helpful for patients affected by a neural tube defect is to drink plenty of fluids and to eat a diet rich in fiber. Both should keep the stool soft and thus facilitate bowel movements. Physical therapies allow the patient to become and remain mobile and thus independent. It is therefore essential to take advantage of the therapies prescribed by the doctor.
