Congenital hydrocephalus is when a child is born with an excessive accumulation of cerebrospinal fluid (CSF) in the brain. CSF is a clear fluid that surrounds the brain and spinal cord. This excess fluid causes an abnormal widening of spaces in the brain called ventricles (ventriculomegalia) and can create a harmful pressure on brain tissue.[3463] Symptoms of hydrocephalus vary and may include an unusually large head with thin, transparent scalp, bulging forehead with increased spaces between the bones of the skull (fontanelles), and a downward gaze. Other symptoms may include seizures, abnormal reflexes, slow heartbeat and respiratory rate, headaches, vomiting, irritability, weakness, and visual problems.[3463][11570][14305]
It is caused by genetic and non-genetic factors. The most common cause of congenital hydrocephalus are variations (mutations) in the L1CAM gene, where there is a narrow passageway between the third and fourth ventricles (aqueductal stenosis). Other causes include mutations in many other genes, brain and/or spinal cord malformations, infections, bleeding inside the cavities of the brain (intraventricular hemorrhage), trauma, exposition to certain drugs (teratogens) or a congenital tumor of the brain.[3463][14305] Congenital hydrocephalus can be an isolated malformation or be part of a syndrome where there are other associated malformations.[3463] It is most often treated by surgically inserting a shunt system to transport the excess CSF and allow for re-absorption. If left untreated, blindness and continuing mental deterioration may occur.[3463][11570][14305]
Hydrocephalus may be subdivided according to the particular defect that exists in the brain and whether the cerebrospinal fluid pressure is high or normal:[3463][14306]
There are also 2 other forms of hydrocephalus that usually affect only adults:[3463][14306]
Hydrocephalus may also be classified in congenital or acquired. Acquired hydrocephalus develops at the time of birth or at some point afterward and may be caused by injury or disease.[3463][11954]
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