Encephalocele is a debilitating condition that is frequently associated with a host of cranial and facial abnormalities. Read and know more about the types, symptoms, causes, diagnosis, treatment and prognosis of this life-threatening disorder.
The condition is a rare form of Neural tube defect (NTD) that is observed at the time of birth. In this disorder, the neural tube is unable to close completely during the fourth week of pregnancy. The neural tube is a hollow, embryonic structure that gradually develops into the central nervous system, comprising of the brain and spinal cord. This in turn creates a gap or hole through which cerebrospinal fluid, brain tissue, and the membrane covering the brain (Meninges) protrude into a sac-like formation.
The neurological condition is known by several names like:
Picture 1 - Encephalocele
- Cranium bifidum
The disorder can be classified into a number of forms based on its location.
In this form, the midline of the upper region of the skull is affected. An extrinsic mass protrudes through the front region of the skull. It is also called “Anterior Encephalocele” and is the rarest form of the condition.
A cutaneous mass invariably occurs in the midline, but posterior to the parietal eminence. Parietal bones are bones in the human skull that form the sides and roof of the cranium when joined together. The center of the smooth, external surface of these bones is marked by a prominent section called parietal eminence.
The congenital form is manifested by large but rare lesions that project through the occipital region, which constitutes the back and lower part of the cranium or skull. The lesions can vary from small pedunculated swellings to big lumps. These large growths can be even more than 20 cm in diameter. In some cases, the abnormal masses may exceed the size of the head from which they arise. The condition often poses a big surgical challenge. The type is more likely to be associated with other neurological abnormalities and is also called “Posterior encephalocele”.
The condition can be further classified into the following subtypes:
Congenital abnormal masses develop between the nasal and the forehead region.
The malformation is specifically observed between the nose and ethmoid sinus – the two of the four-paired paranasal sinuses of the ethmoid bone. This particular bone in the skull separates the nasal cavity from the brain.
In this sub-type, the sac-like protrusions are present between the nasal region and orbit- the cavity or socket of the skull in which the eye and its appendages are situated.
The spinal cord develops normally in this type, but the cerebral or spinal meninges protrude from an opening in the skull or the vertebral column. In this form, the bulging mass contains only the cerebrospinal fluid and is absent with neural tissues.
The condition is marked by sac-like protrusions of the brain tissues and meninges through a defect in the skull.
The condition normally affects 1 out of 5000 live births worldwide. Occipital Encephalocele is more common in Europe and North America, whereas Frontal Encephalocele is more often seen in Africa, Malaysia, Russia, and Southeast Africa.
The disorder is generally accompanied by many craniofacial anomalies that comprises of a group of deformities in the growth of the head and facial bones. Other forms of malformation in the brain may also occur in this type of neural tube defect. Some of the general symptoms observed in the affected individuals are:
It is the most severe form of cerebral palsy in which all the four limbs and the trunk are adversely affected. Affected individuals develop problems in the muscles that control the mouth and tongue, difficulty with speech, and mental deficiency. A few patients may even develop motor impairment.
In this condition, affected patients may experience poor coordination and unsteadiness due to the failure of the brain to regulate the posture of the body as well as the movement of limbs. Lack of muscle coordination is due to a defect in the cerebellum that lies beneath the back section of the cerebrum.
It is rare medical disorder in which the circumference of the head is smaller than normal due to incomplete development or growth of the brain.
In this disorder, there is an abnormal buildup of cerebrospinal fluid in the ventricles of the brain. The tremendous pressure exerted by the fluid can compress and damage the brain.
Individuals with this condition may have frequent episodes of epileptic attacks or fits due to sudden onset of abnormal electrical discharge within the brain.
Vision impairment or functional loss of vision may occur at varying degrees in patients with naso-orbital form of the disorder.
In this condition, an affected child may not reach the developmental milestones at the same time as other children of the same age.
Sufferers usually have below-average intellectual function and decreased learning ability.
The exact etiology of this condition has not been determined by the medical experts yet. As aforementioned, the neural tube fails to close completely during fetal development, causing sac-like protrusions of the meninges. These congenital abnormalities may arise due to a genetic cause. It is more common in families with a history of spina bifida and anencephaly, both of which are severe neurological disorders. Exposure to certain environmental substances before or during pregnancy may inhibit the proper development of the neural tube during the embryonic stage. Some of these substances include:
- Teratogens: These substances interfere with fetal development, causing birth defects.
- Trypan blue: It is a vital stain used to color dead tissues or cells blue.
- Arsenic: It is a poisonous element found in nature whose minimal exposure could be detrimental to the fetus.
Obtrusive deformities mark the presence of the condition and could be easily detected after the birth of an infant. Diagnosis, however, could be difficult in individuals with small defects such as in the nasal or forehead region. In addition to these anomalies, there are several growth and mental retardation issues that are commonly seen in the affected patients.
Imaging studies, comprising of the computerized tomography (CT) and magnetic resonance imaging (MRI) may assist physicians to diagnose the small lesions, commonly found in the nasal region.
Evaluation of the cerebrospinal fluid in the case of meningocele or encephalomeningocele can be performed by inserting a needle into it within the spinal canal. The test is done to determine the cause of increased pressure in the brain, which is due to hydrocephalus. It can also help in finding out the other related neurological abnormalities.
The treatment of the congenital disorder depends on its type and severity. Surgical correction of the defect that develops in the skull of the neonates is the only technique to treat the condition. Large protrusions can be removed easily without any major loss in the developmental stages of the infants. The basis of the treatment is to close the defect in order to prevent infection and desiccation or drying of the brain. The non-functional cerebral tissues, lying outside the cranium are also removed. There is a high chance of nasal elongation or long nose deformity during a total craniofacial construction. In order to avoid this problem, proper surgery as well as management of the condition is highly essential. The steps that are usually followed during surgery involve:
Picture 2 - Encephalocele Image
- Repositioning of the protruding mass into the skull
- Removal of the lumps
- Correction of the deformities to reduce the pressure that would otherwise delay the normal development of the brain
For the majority of Encephalocele patients, the post-surgical prognosis of the condition depends on factors like:
- Location of the protrusions
- Type of brain tissue involved
Affected individuals can grow normally in the absence of any developmental delays and if the surgery is successful. However, if both neurologic and developmental problems arise health care providers must focus on reducing these anomalies. Complete recovery is possible if much of the bulging mass consists of cerebrospinal fluid. On the other hand, only a few complications may develop if the condition involves a large amount of brain tissue.
Although the condition cannot be prevented completely, certain steps can be taken to decrease the chances of development. Proper intake of folic acid in the first few weeks of pregnancy may reduce the occurrence of this form of NTD. Folate is an important constituent in the synthesis and regulation of new cells required for DNA and RNA synthesis. It is also plays an essential role in the nucleic acid synthesis and methylation. Physicians normally recommend pregnant women to consume 400 micrograms of folic acid daily. It is also important to refrain from smoking and drinking to ensure proper growth of the fetus.
Encephalocele accounts for the highest number of fetal deaths worldwide due to which many women go for an early pregnancy termination. Pre-natal screening is very essential for timely recognition of the condition. Despite the poor prognosis of this disorder, many women continue their pregnancy. In such cases, health care providers must offer palliative care as an option to the newborns.