Also known of as cranium bifidum, encephalocele describes a rare defect where a baby’s skull does not close properly during development.
Parts of the brain or the membranes that cover it (meninges) protrude through the opening that is left in the skull.
The encephalocele may occur as a groove in the middle of the skull between the forehead and the nose or at the back of the skull.
The severity of the condition varies depending on where the encephalocele is located.
Types of encephalocele
Encephaloceles are classified according to their location as one of the following:
If the protruding portion contains cerebrospinal fluid (CSF) and meninges, it may be referred to as a meningocele, while a bulge that contains brain tissue may be called a meningoencephalocele.
Encephaloceles are rare, occurring in 1 in 5,000 live births worldwide. In Europe and North America, encephaloceles are more likely to affect the back of the head and in Southeast Asia, Africa and Russia, they are more likely to affect the front of the head. The condition is more common among families that have a history of spina bifida.
The defect occurs because the neural tube does not completely close during fetal development. It is not clear exactly why this happens, but studies have suggested that certain toxins such as arsenic and trypan blue can damage the fetus and cause an encephaolcele to form. Maintaining adequate folic acid levels before and during pregnancy has been shown to help prevent this neural tube defect and women who are trying for a baby are advised to take a 400 mg supplement of folic acid each day.
Encephaloceles often give rise to deformity of the brain and craniofacial abnormality. Some of the symptoms seen in this condition include hydrocephalus (build up of CSF in the brain), paralysis of the limbs, microcephaly (small head size), ataxia (uncontrolled muscle movement), delayed growth and development, convulsions and vision problems.
Diagnosis and treatment
The presence of an encephalocele is often immediately noticeable after birth, although a small defect in the nose or forehead area may go undetected at first.
Currently, the treatment is reparative surgery, which is usually performed during childhood/infancy. The success of surgery depends on the location and size of the encephalocele but large protrusions can generally be managed without causing major disability. Bulging areas of brain material are pushed back inside the skull, correcting the deformity and relieving the pressure that can hinder normal brain development. Sometimes, shunts may be inserted to drain excess CSF from the brain.
Reviewed by Sally Robertson, BSc