*3.1.2 Iniencephaly*

It is a rare severe defect of the occipital bone, with cervical spina bifida and retroflexion of the head on the cervical spine. An occipital encephalocele may be present. Like anencephaly, there is a strong female preponderance (**Figure 2**).

**107**

*3.1.3 Anencephaly*

*Diagram of iniencephaly.*

**Figure 2.**

(**Figure 3**) [12].

*3.1.4 Myelomeningocele*

the meningeal sac.

**3.2 Closed NTDs**

*3.2.1 Encephalocele*

and ventricle).

*Common Congenital Neural Tube Anomalies: Epidemiology, Classification, Management…*

In this defect, the cranial portion of the neural tube fails to close, resulting in exencephaly. This ends up in the neural tissue getting a destructive exposure to an intra-amniotic environment which turns the exencephaly into anencephaly

In this defect, the posterior part of the spinal portion of the neural tube fails to close; This defect occurs most commonly in the lumbar region. A bony defect in the vertebral arch provides the condition for the meningeal sac to herniate (**Figure 4**). Myelocele is a similar condition that involves the spinal cord without protrusion of

It is defined as a sac-like protrusion of the brain accompanied with or without meninges through an opening in the skull (**Figure 5**). According to the type of involved tissues, encephaloceles are classified as meningocele (herniation of meninges), encephalomeningocele (herniation of both meninges and brain), and encephalomeningocystocele (herniation of meninges, brain,

*DOI: http://dx.doi.org/10.5772/intechopen.97182*

*Common Congenital Neural Tube Anomalies: Epidemiology, Classification, Management… DOI: http://dx.doi.org/10.5772/intechopen.97182*

**Figure 2.** *Diagram of iniencephaly.*

*Congenital Anomalies in Newborn Infants - Clinical and Etiopathological Perspectives*

dysraphism (OSD) with cutaneous stigmata to be 2.8% [10].

In general, NTDs are classified into open and closed defects [11].

This is the most severe presentation of NTDs and involves both the spinal and cranial parts of the neural tube (**Figure 1**) [12]. Craniorachischisis is a combination of anencephaly with a contiguous bony defect of the spine, both without the neural

It is a rare severe defect of the occipital bone, with cervical spina bifida and retroflexion of the head on the cervical spine. An occipital encephalocele may be present. Like anencephaly, there is a strong female preponderance (**Figure 2**).

Despite remarkable developments in diagnostic technologies and therapeutic modalities, the epidemiology of congenital CNS anomalies has not changed significantly. The prevalence of CNSA varies widely according to geographic regions and socioeconomic situations and is reported to be between 1 and 10 in every 1000 live births [7, 8]. The incidences of anencephaly and spina bifida per 10000 births range from 0.7 in central France to 0.9 in Canada, 7.7 in the United Arab Emirates, and 11.7 in South America [9]. A recently published systematic review and metaanalysis, which included 6558 infants, has reported a prevalence of occult spinal

**2. Incidence**

**3. Classification**

**3.1 Open NTDs**

*3.1.1 Craniorachischisis*

tissue's meningeal cover.

*3.1.2 Iniencephaly*

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**Figure 1.**

*Diagram of Craniorachischisis.*

## *3.1.3 Anencephaly*

In this defect, the cranial portion of the neural tube fails to close, resulting in exencephaly. This ends up in the neural tissue getting a destructive exposure to an intra-amniotic environment which turns the exencephaly into anencephaly (**Figure 3**) [12].

#### *3.1.4 Myelomeningocele*

In this defect, the posterior part of the spinal portion of the neural tube fails to close; This defect occurs most commonly in the lumbar region. A bony defect in the vertebral arch provides the condition for the meningeal sac to herniate (**Figure 4**). Myelocele is a similar condition that involves the spinal cord without protrusion of the meningeal sac.

### **3.2 Closed NTDs**

#### *3.2.1 Encephalocele*

It is defined as a sac-like protrusion of the brain accompanied with or without meninges through an opening in the skull (**Figure 5**). According to the type of involved tissues, encephaloceles are classified as meningocele (herniation of meninges), encephalomeningocele (herniation of both meninges and brain), and encephalomeningocystocele (herniation of meninges, brain, and ventricle).

**Figure 3.** *Diagram showing anencephaly.*

#### **Figure 4.**

*Diagram showing spina bifida occulta, memingocele and myelomeningocele.*
