Introduction

Any condition that affects newborns or unborn babies can be a cause for worry among new parents. Delivery of a healthy baby is every parent’s greatest wish, and unfortunately, it is not always the case due to unforeseen circumstances. Many conditions that can affect newborn babies can be treated when caught early and allowing the child to live a self-sufficient and fulfilling life. This article seeks to define Encephalocele and aims to provide information on this rare condition, how it is diagnosed and managed and can encourage further research.

What is encephalocele?

Encephalocele is a rare defect that occurs during the development of a foetus, belonging to a group of defects called Neural Tube Defects, which play an important role in the development of both the brain and spinal cord. The neural tube begins as a groove in the foetus and folds over to form the brain and spinal cord. When the neural tube does not close completely during development, it can cause neural tube defects. 

Encephalocele is a rare defect that occurs when there is an opening in the skull and a protrusion of a sac that contains brain matter and meninges, a covering for the brain and spinal cord, externally. When the sac contains only meninges, it is referred to as a meningocele. This opening can occur anywhere along the skull from the nose to the back of the head.

Usually, the defect is located along the midline and covered by skin containing brain matter, including the meninges. Encephalocele may also occur asymmetrically. Internal encephaloceles may occur and are usually discovered later in life during evaluation of conditions like epilepsy.

Encephalocele usually occurs in approximately 1 in 10000 live births, representing around 15% to 20% of Neural Tube Defects. Rarely, encephaloceles may develop from a tumour or a traumatic event, causing the protrusion of brain matter through a defect.

Types of encephaloceles

There are different types of encephaloceles that can occur: 

• Occipital Encephalocele- Encephalocele at the back of the head

This is the most commonly seen type of encephalocele and occurs when the protrusion happens at the back of the head or the skull base.

• Anterior Encephalocele- Encephalocele that occurs in the Front part of The Head

The protrusion of the sac is near the forehead or near the nose. There are many theories attempting to explain this type of encephalocele. One of the theories suggests a failure of neural folds joining anteriorly, causing skull development failure. An alternative theory suggests that there may be a malformation in the bone at the front, resulting in the protrusion of the sac.. This type of encephalocele may result in facial deformities, including increased distance between the eyes.

• Parietal Encephalocele- Encephalocele occurring in the parietal region of the skull

This is the rarest form of encephalocele. The parietal region refers to the region in the head formed of two large parietal bones that form the upper sides and top of the skull. When an opening or a defect occurs in this region, it can lead to the protusion associated with encephalocele.

Risk factors and causes of encephalocele

The specific cause of encephalocele has not been identified. Research shows that there is an intermingling of inherited factors and environmental factors that may result in neural tube defects. 

The risk of an encephalocele in an isolated birth is between 2% to 5%. In 10% of cases, abnormalities of the chromosomes, the structures which carry genetic material and DNA, are detected. These may be more common, especially during inbreeding or marriage between close relatives, where defective genes are carried on within the family.

Infections during early pregnancy, such as Toxoplasma, herpes Simplex virus, Rubella, and Cytomegalovirus, have been implicated in the development of encephalocele. 

Acquired forms of encephalocele are rare and may arise from tumours, surgical procedures and injuries that cause protrusion of brain matter.

Presentation of encephalocele

The identification of encephaloceles is governed by the location and size, and is usually presented as a lump covered by skin. If the skin is broken or ulcerated, this can increase the risk of infection, including meningitis. 

The most common type of encephalocele is the occipital encephalocele, which is located at the base of the skull and the protrusion is covered by skin containing cerebrospinal fluid; therefore may appear translucent. Seizures may occur when affected by this type of encephalocele. Hydrocephalus, due to fluid buildup in the head,  is also a common occurrence in occipital encephaloceles.

An anterior encephalocele involving the area around the nose may cause nasal obstruction, resulting in breathing difficulties and snoring. Leakage of cerebrospinal fluid through the nose and facial disfigurement are other common types of side effects observed in this type of encephalocele.

Diagnosis of encephalocele

Diagnosis of encephalocele can happen both before birth (prenatal) or after birth (postnatal).

Prenatal diagnosis can be made using an ultrasound to visualise the defect. However, MRI scanning of the foetus can enable better diagnosis. These findings must always be confirmed in the postnatal period through physical examination, use of X Ray, CT scans and MRI scans of the newborn. The confirmation also allows differentiation from any other skull defects that may have a similar presentation.

Smaller-sized encephaloceles may be missed at birth and present with developmental issues, including:

• Hydrocephalus is due to a fluid buildup in the brain
• Growth delay
• Visual issues
• Flaccid arms and legs due to loss of tone
• Seizures
• A small head
• Delay of development milestones

Management of encephalocele

Encephalocele can be diagnosed prior to delivery (prenatal period) using ultrasound and foetal MRI scans that would show the deformity. Testing the amniotic fluid for genetic abnormalities may also be carried out during this period. If diagnosed in the prenatal period, the pregnant mother should consult with different specialists to understand the condition and the expectations better. Genetic counselling is also advisable to explain any future complications which may occur. 

The risks associated with the pregnancy and delivery should clearly be discussed, as the patient may be offered the option for early pregnancy termination.

When the pregnancy is carried to term, delivery should be carefully planned to involve paediatric, surgical and neurology specialists in a hospital with excellent facilities or access to a neonatal care unit. Delivery is ideal at 38 weeks of pregnancy via caesarean section to avoid damaging the exposed tissue through vaginal birth.  However, this should always be discussed with a specialist in advance to ensure the best treatment option., 

Treatment can vary and is determined by the different aspects and properties of the encephalocele. The location, size, presence or absence of the skin-protective covering, and the extent of the protrusion are some factors that should be taken into consideration before making any important decisions. Surgical intervention by neurosurgery specialists is the mainstay of treatment. 

Surgery can be conducted to restore the protruding tissue into the skull and to close the defect tightly, allowing the protection of the brain matter. Surgical intervention can be delayed when there is a skin covering over the encephalocele. In the absence of skin or in situations where there is damage, emergency surgery can be performed to protect the brain from infections and injury to brain matter. 

Outcomes and impact of encephalocele

Prognosis of encephalocele can be determined by the location, size and contents of the defect.

Encephaloceles vary in size. Larger encephaloceles may risk more developmental impairment compared to smaller encephaloceles. Common complications associated with encephaloceles include: 

• Development Disabilities
• Hydrocephalus
• Neurological deficiencies
• Meningitis
• Leakage of cerebrospinal fluid
• Recurrence following surgery

Posterior encephaloceles carry a higher risk of disability and death compared to other types of encephaloceles. 

When other severe malformations exist concurrently with encephaloceles, the risk of death is increased due to complications from these other malformations.

When premature delivery occurs or the growth of the foetus is restricted in the womb, there is a higher chance of stillbirths and death soon after birth.

Summary

To summarise, encephalocele is a malformation that may occur in the foetus and newborn. The cause of congenital encephalocele has not been stated clearly. It is thought to have multiple factors leading to its development, including genetics, factors in the environment, infections during early pregnancy, and some drugs. There may also be a relation between the development of neural tube defects and folate deficiency. This has not been proven, however. Research suggests that the use of folic acid prior to and during the first trimester of pregnancy may reduce the risk of neural tube defects.

Encephalocele may be acquired due to injury, tumours, or post-surgery, resulting in a defect that allows protrusion of brain matter.

When an encephalocele is diagnosed, examination should be done to find other malformations, as they tend to occur concurrently.

The survival of foetuses with encephalocele depends on the type, location and contents of the defect. It is also affected by the presence or absence of other malformations and their severity. 

Damage to brain tissue is likely to occur, especially when active neurological tissue is contained in the defect, resulting in altered mental capabilities and developmental inadequacies. 

The delivery of babies with diagnosed encephalocele should be done at a hospital with a paediatric intensive care unit and neonatal specialists. Ideally, the delivery is done via caesarean section to minimise damage to the protruding sac containing brain tissue.

Children with encephaloceles have been shown to live long, fulfilling lives with proper care and management.