Abstract
Neural tube defects are a common occurrence in many pregnancies. Some of them have fairly minimal consequences and in fact, many children born with these defects lead normal lives. Spina bifida is one of these defects and is indeed one of the most common. The defect emanates from the failure of the neural tube to close properly leaving an opening. This paper aims to look at this defect from several perspectives including a brief description of the disorder, clinical presentation, pathophysiology, the usual age of onset and relevant ethnic and cultural risk information. The paper will also look at the genetic issues associated with the disease. Finally, the paper will explore the diagnostic process, medical management and prognosis of the disease.
Spina bifida is a congenital defect that affects the spine and that manifests itself during pregnancy. It is ranked as the most common birth defect of the central nervous system (Fletcher & Brei, 2010). The prevalence for the disease on a global scale is 1 in every 1000 births. The disease is plagued by a lot of complexity and consequently, the diagnosis as well as the treatment of infants who are born with the defect often begins prior to birth and throughout adulthood and involves multiple disciplines. Because of the prevalence of the defect in recent decades, research on it has flourished and currently, there are vast literature resources on it.
Spina bifida is classed as neural tube defect which occurs at any place along the human spine if the neural tube fails to close fully (Fletcher & Brei, 2010). It sometimes results in a situation whereby the vertebrae that overlies the spinal cord does not form fully and therefore remains unfused leaving a significant opening. The opening can sometimes be so large such that some part of the spinal cord actually protrudes through it. Occasionally the protruding part of the spinal cord may be surrounded by a sac filled with fluid (Fletcher & Brei, 2010).
In regard to the disease’s pathophysiology, the disease emanates from the failure of the neural tube to close in the first four weeks of embryonic development. This is at a stage when the mother is unaware of her pregnancy. In normal cases, the neural tube closure is supposed to take place precisely 25-28 days after the mother’s egg has been fertilized (Green et al., 2009). Research shows that there are a couple of human factors and conditions that increases the chances of the neural tube failing to close. This includes ingestion of medications such as anticonvulsants, obesity, high body temperature of the mother from either fever or other artificial sources such as electric blankets or hot tubs.
It has also been shown that a deficiency of folic acid is another factor that contributes actively to the pathogenesis of the disorder. In fact, mothers are often encouraged to take a high dosage of folic acid, such as 4mg/ day before the pregnancy and even in the course of it. Doing this significantly decreases the probability of the disorder’s development disorder by a massive 70% (Green et al., 2009).
Research has also been shown that the prevalence of the disorder varies significantly with gender, race and ethnicity. In regard to gender, the defect is more common in girls than in boys. However, scientific explanations for this trend are yet to be established. In term of race, the defect tends to be more common in white and Hispanic women than in black women black women (Bullet et al., 2009). For example, statistics show that the prevalence of the disease is lower by 30% for black children than for white children (Bullet et al., 2009).
There are several versions of spina bifida with the most common being spina bifida occulta, spina bifida meningocele and spina bifida myelomeningocele (Mitchell et al., 2004). Each of these versions clinically present themselves in different ways.
The occulta version is associated with; a dimple or depression in the lower back, soft fatty deposits, a small hair patch at the lower back and finally a port-wine nevi. The meningocele version may present itself via a saclike cyst protruding outside the spine. The occulta and meningocele versions are not usually associated with neurological deficits. The two types of spina bifida may however be accompanied by bladder and bowel incontinence. The third type of spina bifida- the spina bifida myelomeningocele- presents more severe impairments. These include, bladder incontinence, spastic or flaccid paralysis, hydrocephalus, musculoskeletal deformities (such as hip dysplasia, scoliosis, clubfoot, knee contracture and hip dislocation), postural reactions that are delayed and trunk hypotonia (Au et al., 2010).
Although much research has been conducted on spina bifida, even more needs to be done in order to fully establish the relationship between the disorder and genetics. Scientists have not been fully able to explain the genetic and hereditary questions regarding spina bifida.
A genetic link however exists because at least 70% of spina bifida cases are associated with folic acid deficiency which is a suggestion of the presence of a genetic metabolic link (Au et al., 2010).
In the general population, the chances of a child having the defect are 0.1 to 0.2 %. If a mother has previously had a child with the disorder, the chances of the mother having another affected child are 5% (Au et al., 2010). These chances are further accentuated if, in the family, there has been a relative who has given birth to a child with the disorder. In addition, a mother who herself was born with the defect has a higher chance of having a child with the same disorder. However, only about 5% of all spina bifida cases involves direct heredity effects. Therefore, a woman with spina bifida only has about 1 to 5% of having a child with the defect (Au et al., 2010). The chances are increased to about 15% if both parents were born with the disorder. This shows that spin bifida is a very complex condition that does not merely involve passing of genetic characteristics from the parent to the child.
Preliminary research has however been able to identify some genes that are associated with the condition. For example, some genes in the body that are involved in the metabolism of glucose are linked with people born with the disorder (Au et al., 2010). An example of this gene is VANGL 1 (Au et al., 2010). Another gene known as MTHFR has also been linked with the disorder. This is a gene that is essentially a code for one of the proteins utilized in the metabolism of folic acid (vitamin b9) whose deficiency has been proven to be directly related to spina bifida cases (Au et al., 2010).. Another gene that is also related to the metabolism of folic acid is SMHT1 and cases of spina bifida are more common in people where this gene has been altered (Greene et al., 2009). The mentioned genes are affected more than others depending on the race (Au et al., 2010).
Therefore as shown, there is still more information that needs to be established in regards to the relationship between spina bifida and genetics. The closest that scientist have gotten to pin-pointing the direct genes that are associated with the disease is a study that was conducted by a team of researchers in Genoa, Italy. This was at the Instituto G. Gasilini. This team of researchers was able to establish three specific mutations of the VANGL1 gene that implicate this gene as a potential risk factor for neural tube defects such as spina bifida.
For mothers trying to have a baby or who are in the initial state of pregnancy, it is recommended that they visit physicians for testing and so that migratory measures can be taken to alleviate the consequences of the condition in the infant (Au et al., 2010)..
The most common diagnostic process of spina bifida involves several prenatal screening tests. One of these is the screening of the maternal blood. Maternal blood screening tests the amount of alpha-fetoprotein (AFP) whose high levels in the maternal blood can be an indication that the baby has spina bifida (Cameron and Moran, 2009). Here, blood is drawn from the mother and tested for AFP (a protein that is produced by the baby). Small amounts of AFP cross over the placenta into the blood stream of the mother and this is perfectly normal. However, large amounts of AFP could be an indication of a neural tube defect (Cameron and Moran, 2009).
The other option for diagnosis and testing is ultrasound. If high levels of AFP have been indicated, an ultrasound can be carried out to establish why this is the case. An ultrasound will explicitly show any spinal defects, for instance, an opening in the spine or even some brain features in the baby that could suggest the presence or occurrence of spinal bifida.
Amniocentesis is the other method that is used for diagnosis. Here the doctor uses a medical needle to draw a little sample of amniotic fluid from the fluid sac surrounding the baby. Levels of AFP are the tested from the drawn sample. If there is an open neural defect in the baby, there is a high AFP level in the amniotic fluid sac since this protein can leak into the baby through the opening (Au et al., 2010).
The management and prognosis of the defect involve several aspects. A newborn who has been born with the neural tube open should be carefully nursed, and the specific section of the spine where the defect is conspicuous should be covered with a sterilized and wet saline dressing (Cameron & Moran, 2009).
A multidisciplinary approach is however needed when it comes to managing the defect in a child with the disorder. This multidisciplinary approach should incorporate aspects of treatment as well as coping mechanisms. Treatment may involve physical surgery to rectify the defect while coping mechanism are aimed at helping the bay to cope with condition and lead a relatively normal life.
Treatment should have the aim of maximizing the infant mobility, ameliorating or preventing spina bifida complications and encouraging normal development, as well as the leading of an independent life.
Management of the disease can also involve repair measures. For instance, surgery of the fetus can be done in the first few days of life to correct the malformation of the spinal cord. For instance, if the spinal cord is expose, the surgeon can perform an operation to push back the exposed tissues or nerves back into the body of the baby.
Orthopedic assessment and consequent orthopedic surgery are other forms of intervention. Orthopedic surgery becomes necessary when the patient experiences problems related to bone development. Physiotherapy has also been found to be very effective in the management process. Children are often given adaptive training that enables them to function properly in spite of the disease.
Conclusion
As shown in the above discussion, Spina bifida is a congenital defect that affects the spine. This defects manifests itself during pregnancy. It is one of the many neural tube defects and occurs when the vertebrae that overlies the spinal cord does not form fully and therefore remains unfused leaving a significant opening. Although the disease does not follow the conventional patterns of disease heredity, genetic links to the disorder have been established. The research on the same is not conclusive and even more needs to be done. Pregnant mothers can undergo screening to establish the probability of occurrence of the disease in their children. When it comes to the defect's management, a multidisciplinary approach that incorporates both treatment and coping mechanisms is needed.
References
Au, K. S., Ashley‐Koch, A., & Northrup, H. (2010). Epidemiologic and genetic aspects of spina bifida and other neural tube defects. Developmental disabilities research reviews, 16(1), 6-15.
Boulet, S. L., Gambrell, D., Shin, M., Honein, M. A., & Mathews, T. J. (2009). Racial/ethnic differences in the birth prevalence of spina bifida-United States, 1995-2005. Morbidity and Mortality weekly report, 57(53), 1409-1413.
Cameron, M., & Moran, P. (2009). Prenatal screening and diagnosis of neural tube defects. Prenatal diagnosis, 29(4), 402-411.
Fletcher, J. M., & Brei, T. J. (2010). Introduction: Spina bifida—A multidisciplinary perspective. Developmental disabilities research reviews, 16(1), 1-5.
Greene, N. D., Stanier, P., & Copp, A. J. (2009). Genetics of human neural tube defects. Human molecular genetics, 18(R2), R113-R129.
