If these complications do occur, then the baby is at risk of developing a haemorrhage from rupture of the fragile vessels. This can lead to a blood clot developing, which in some cases is big enough to break through the wall of the ventricle. Should the clot block the flow of CSF, the baby will develop hydrocephalus. The blockage may be temporary or permanent. Even if a blood clot does not develop, the blood cells from the haemorrhage can cause blockage.
Most babies born with spina bifida have hydrocephalus.
In addition to the lesion in the spinal cord, there are abnormalities in the structure of certain parts of the brain which develop before birth. The increase in pressure due to this can also compress the abnormal parts of the brain even further. This is an infection of the membranes covering the brain. The inflammation and debris from this infection block the drainage pathways resulting in hydrocephalus. Meningitis can occur at any age but it is more common in children.