An encephalocele (pronounced en-kef- a-lo-seal) is a rare neural tube defect, which is present at birth. It may also be known as cranium bifida.
Encephaloceles occur when the bones of the skull do not fuse properly during early fetal development, creating a gap. A protruding sac-like formation occurs in this gap. The sac may be covered in skin or just a thin membrane, and can contain the membrane that covers the brain (meninges), cerebrospinal fluid, brain tissue, and sometimes blood vessels.
At the moment we don’t have all the answers to this. We know there are many factors which can increase the risk of a baby having a neural tube defect. In most cases, an encephalocele occurs sporadically (out of the blue), but some can occur where there is a previous family history of neural tube defects.
Occipital encephaloceles are more common in Europe and North America, whereas anterior encephaloceles are more common in Southeast Asia, Africa, Malaysia and Russia. They occur in 1 in every 5,000 births.
Occasionally, encephaloceles are small and aren’t diagnosed until the baby is born. Most often they are diagnosed by ultrasound scan early in pregnancy. Some parents may choose to end the pregnancy at this stage.
If the pregnancy continues, delivery of the baby is usually by a planned caesarean section. Further assessment and imaging of the baby after birth will provide more information to the extent of the encephalocele.
The location of the encephalocele, its size, the contents of the protruding sac, and how it is treated – as well as the possibility of the presence of other conditions – will all affect the outcome for your baby.
Some very large encephaloceles may be incompatible with life, and affected babies may not survive the pregnancy.
For babies with a smaller anterior encephalocele, there’s less likelihood that brain tissue will protrude into the sac. In these cases, surgery – performed by a neurosurgeon – can have a good outcome.
Encephaloceles with small protruding sacs in the midline and occipital areas, and no involvement of brain tissue can usually be improved or reduced by neurosurgery.
Where brain tissue and blood vessels are present in the protruding sac, surgery is more difficult and may even be too risky to undertake. Consultations and assessments by specialists including neurosurgeons, craniofacial specialists and plastic surgeons (a multidisciplinary team) will be undertaken to decide if surgery is a possibility.
The risks are high and – if it can go ahead – surgery is performed in a specialist hospital which has previous experience of this type of surgery.
This depends on the assessment of the baby, whether the protruding sac is covered in skin or just a fine membrane, and the contents of the sac. Extensive assessment will be required and it may be necessary for any planned intervention to be done in stages.
A shunt may be inserted to relieve some of the pressure caused by the build-up of cerebrospinal fluid.
Sometimes surgery may be done only to assist with management of the encephalocele and to help with palliative care.
Each baby is different, and – much like approaches to surgery – the challenges they face will depend on the size and location of the encephalocele, as well as the extent of the involvement of brain tissue and blood vessels.
Small, frontal encephaloceles tend to have a better outcome with minimal issues
after surgery. Larger encephaloceles involving brain tissue and blood vessels pose a greater risk of associated difficulties.
Common issues may include hydrocephalus, visual problems, epilepsy, neurological problems, developmental delay, paralysis of limbs, microcephaly, delayed growth, uncoordinated muscle movement, and learning disability.
Before planning another pregnancy, it is important to take a daily high dose of folic acid (5mg), which is available on prescription only, at least two months before conceiving. Vitamin B12 taken alongside may also help. By doing this the risk of conceiving a baby with any neural tube defect is greatly reduced. Genetic counselling may be helpful as part of your planning, and your GP can refer you for this.