**Abstract**

The spina bifida is a congenital anomaly that results in an abnormal formation of the spine and the spinal cord. The two dominant types of spinal dysraphism are based on appearance - open spina bifida if the lesion is visible and closed spina bifida if the lesion is not visible on the body surface. These conditions lead to a different spectrum of neurological effects according to the degree of neurulation disruption. The prevalence of neural tube defects has different rates among different ethnicity, geography, gender, and countries. Genetic, nutritional and environmental factors play a role in the etiology and pathogenesis of the spina bifida. Congenital anomalies in the vast majority concern children living in the early neonatal period who have important medical, social or educational needs. The lifetime cost of a child born with the spina bifida is estimated at over €500,000.

**Keywords:** neural tube defects, spina bifida, spinal dysraphism, etiology, pathophysiology, meningomyelocele

### **1. Introduction**

Spinal dysraphism encompasses congenital problems that result in an abnormal bony formation of the spine and the spinal cord. This congenital pathology is caused by the maldevelopment of the ectodermal, mesodermal, and neuroectodermal tissues. The spina bifida is a congenital anomaly that arises from incomplete development of the neural tube. It is commonly used as a nonspecific term referring to any degree of neural tube closure. The two dominant types of spinal dysraphism are based on the appearance – spina bifida aperta if the lesion is visible and spina bifida occulta if the lesion is not visible [1]. Common manifestations are meningocele, myelomeningocele, lipomeningocele, lipomyelomenigocele, myeloschisis, and rachischisis [1]. Spinal neural tube defects basicaly exist in two forms – open and closed spinal dysraphism. The most simple form with minimal involvement of nervous tissue is closed dysraphism (spina bifida occulta) where the vertebral defect is hidden. More severe open spinal dysraphisms (spina bifida aperta) mostly represented by meningocele or myelomeningocele result in various degrees of neurological deficit according to affected spine level, extent of lesion and amount of structures involved (**Figure 1**). In this defect there is a communication between nerve tissue and external environment leading to exposure to amniotic fluid and later leads to high risk of infection. Defect can be covered by a thin membrane. The exposed neural tissue degenerates *in utero,* resulting in

**Figure 1.** *Types of spinal dysraphism (public domain, source: wikipedia.org).*

neurological deficit that varies with level of the lesion. The vertebrae at the level of the lesion lacks neural arches, and so are incomplete dorsally. Spina bifida is commonly associated with several other developmental abnormalities which makes a multidisciplinary medical plan paramount to survival and positive outcomes. The spina bifida correlates with cutaneous conditions such as port-wine stain, hemangioma, hypertrichosis, fibroma pendulum, pigmentary nevus, lipoma, dermal sinus, and deviation of the gluteal furrow [2]. Motor and sensory neurological deficit is inconsistent. The result of nerve structures involvement is usually paraparesis – weakness of lower extremities which in more severe degrees leads to impaired walking or immobility. In patients with severe forms of spina bifida degree of disability strongly correlates with axial level of the lesion [3]. Long term 40-years follow-up of 117 children in the United Kingdom who underwent surgical repair during the 1960s and 1970s showed only 17% of survivors with high level of lesion (above T11) and these patients have higher risk of pressure sores and significantly lower possibility to become community walker. Survival in patients with lesion below L3 vertebra was 61%. Loss of skin sensitivity increases the risk of development of pressure sores what makes frequent skin control necessary. Incontinence of stools and urine is very frequent as well as orthopedic complications, such as contractures, talipes, dislocation of the hip joint, kyphosis and scoliosis. Patients with open forms of spina bifida often display also Chiari II malformation (herniation of the hindbrain) and hydrocephalus that could also require shunting procedure. The mobility and the need for care can be predicted from the neurological deficit. [4]. The lifetime cost of a child born with the spina bifida is estimated at over €500,000, of which 37% comprises direct medical costs with the remaining being indirect costs including special educational and caregiver needs, and loss of employment potential. The direct medical cost for spina bifida patients throughout their life is very high. The most significant amount of financial cost consumpts initial diagnosis and early treatment, inpatient care and the treatment of comorbidities in adult life. The indirect lifetime cost in these patients is even higher due to great impact of their increased overall morbidity. The results from the economic evaluations demonstrate that folic acid fortification in food and pre-conception folic acid consumption are cost-effective ways to reduce the incidence of neural tube defects [5, 6]. Considering all possible medical and economic consequences of the issue of diagnosis of spina bifida, there is an emerging need for clarification of exact etiology and pathophysiological mechanisms with emphasis on possible primary prevention, as well as early and effective treatment of spina bifida and also all upcoming complications.

**5**

*Etiology and Pathophysiology of the Spina Bifida DOI: http://dx.doi.org/10.5772/intechopen.97467*

The prevalence of neural tube defects has different rates among different ethnicity, geography, gender, and also countries. The prevalence is higher among Whites as compared to Blacks and females as compared to males [7]. Asia has more rate of neural tube defects than western countries due to low socio-economic status of eastern countries directly affecting the economic burden and negligence over the folic acid as a part of multivitamin supplementation [8]. Worldwide data show place to place-variation of the prevalence rate assumed to be due to low standard health care facilities though the exact mechanism is still unknown. The eastern Mediterranean region exhibited high variability with a swat, Pakistan having 124 cases per 10000 births. The prevalence in the African region ranges from 5.2 to 75.4 per 10000 births, the European region ranges from 1.3 to 35.9 per 10000, and American region ranges from 1.4 to 27.9 cases per 10000. Most WHO member states (120/194) did not have any data on the prevalence of neural tube defects. As the prevalence estimates vary widely, efforts need to be stepped up to monitor neural tube disorders, especially in developing countries. The folic acid supplementation and increasing the quality of the population's diet are important factors in the prevention [9]. A study from Los Angeles showed that the rate of anencephaly and exencephaly is more than spina bifida. But normally, it is supposed that the spina bifida is more common than anencephaly. Same-sex twins had a higher incidence of neural tube defects as well as higher mortality. The study verifies the same etiology between neural tube defects and monozygotic twins. The main role here is played by the common susceptibility to environmental factors [7]. The rate of neural tube defects is more common in twins than singleton and in monozygotic twins than dizygotic twins. The spina bifida most frequently affects lumbosacral spinal level. Only about 0–5% of cases occur in the cervical spine, 5–10% in the thoracic spine, 20–30% in the thoracolumbar junction, 20–30% in the lumbar, 30–50% in the lumbosacral level and 5–15% in the sacral spine [10]. Altogether cervicothoracic spinal dysraphisms are rare, with an incidence of only 1–6,5% [11]. Myelomeningocele occurs in approximately 1 in 1200 to 1400 births. 60% of those children are community ambulators, and 80% are socially continent. The incidence is not higher in any specific ethnic group, but females have a slightly higher incidence in comparison with males [12]. An increased risk of recurrence has been reported of about 3–8% after one affected pregnancy or maternal history of the defect and the risk worsens with an increasing number of affected children [13]. Researchers performed a study in northern China that showed that the recurrence risk in neural tube defects in subsequent pregnancies was 1.7%, which was higher than in the United States. The recurrence rate of neural tube defects was approximately 5-times higher than the overall prevalence in the same region of northern China [14]. The risk of recurrence in myelomeningocele was reported 2–5% in the United States. These data suggest that the genetic basis of closed defects may be same as the basis for myelomeningocele in some families [15]. Another study showed that the recurrence rate has been approximately 2–3% in consecutive pregnancies. Higher incidence rates were reported in females, increased maternal age, and lower socio-economic status. Latin Americans were the most affected population in the United States. Females are affected up to 3- to 7-times more than males [16]. The observed prevalence of the spina bifida varies globally and is largely influenced by differences in surveillance methods, prenatal diagnosis and elective termination policies, and folic acid fortification of staple foods in a given country or region. The spina bifida is more common in countries where there is no legislation providing for the mandatory enrichment of the diet with folic acid in order to reduce its prevalence. African data were scarce, but needed, as many African nations are beginning to adopt folic acid legislation [9, 17, 18]. Ultrasound screening has a major

**2. Epidemiology**
