Congenital: The estimated incidence is 0.2 to 0.8/1000 live births in the United States (2).
Post-infectious hydrocephalus: It is estimated that 1% of children who survive a bacterial meningitis will develop hydrocephalus (4).
Head trauma: Approximately 4% of all patients will require CSF diversion (7).
X-linked hydrocephalus (aqueductal stenosis): X-linked hydrocephalus comprises less than 4% of all cases of hydrocephalus, but it accounts for 8–15% of primary hydrocephalus in boys (15).
Tumors: Approximately 85% of children with posterior fossa tumors present with some degree of hydrocephalus, and about 20–30% develop permanent hydrocephalus (76).
Cranial vault anomalies: Approximately 12% of children with syndromic craniosynostosis develop hydrocephalus (77).
Majority known by 2 years of age: The majority of children who present with hydrocephalus do so before 2 years of age, with most of these cases related either to congenital conditions or to complications of premature birth.
Decreasing incidence with age: After 2 years of age, the incidence decreases with increasing age, with most of these cases resulting from obstructive tumors or aqueductal stenosis.
Only with X-linked hydrocephalus: Aside from X-linked hydrocephalus (which occurs only in males), there is no obvious sex predilection in pediatric hydrocephalus.
None known: There is no known difference in the worldwide geographic distribution of hydrocephalus.
See Relationships below
Relationships to Other Disease States and Syndromes
CNS tumors: Hydrocephalus can result from mechanical obstruction of the CSF pathways, most often in the vicinity of the fourth ventricle, overloading the absorptive capacity of the arachnoid villi by spilling blood or protein into the CSF and overproduction of CSF in cases of choroid plexus papilloma or “hypertrophy.”
Infectious meningitis: Hydrocephalus may occur with bacterial meningitis due to gram-negative organisms, Haemophilus influenzae, Streptococcus pneumoniae, group B streptococci, and other bacterial organisms, and, less commonly, tuberculosis, toxoplasmosis, and viral meningitis and encephalitis.
Cranial vault anomalies: Chronic venous hypertension due to jugular foramen stenosis has been proposed as an etiology for hydrocephalus in some children with complex craniosynostosis and achondroplasia. Cerebellar tonsillar herniation may also result in hydrocephalus in some children with this condition.