Congenitally or peri-/postnatally acquired; the former causes are decreasing due to early prenatal diagnosis (1 isolated congenital hydrocephalus in 1000 newborns. With myelomeningocele, congenital hydrocephalus occurs in up to 90 percent as a concomitant malformation), the latter (acquired) causes are increasing on account of rising prematurity (perinatal intracranial hemorrhage).

Without treatment:
1. Increasing macrocrania.
2. Mental retardation or loss of acquired skills with irreversible neuropsychological deficit.

Disturbance in cerebrospinal fluid (= CSF) circulation or absorption.

There are numerous pathologies leading to hydrocephalus, which have a substantial influence on its prognosis.
Congenital: Malformations (as aqueductal stenosis) or acquired during pregnancy (as toxoplasmosis of the mother).
Acquired: Following peri- or postnatal intracerebral hemorrhage or meningitis, or due to a brain tumor.

The clinical presentation depends on the age of the child and on the rate of development of the disturbance in CSF circulation.
Unborns, neonates and infants: Macrocrania and ventriculomegaly in ultrasound. Macrocrania at first clinical presentation (head circumference more than the 97th percentile) or abnormal increase within time. Sunset phenomenon, enlarged and tense anterior fontanel in upright position in a quiet patient, split sutures, dilated scalp veins. Deceleration, arrest or loss of development.
Toddlers and older children: Vomitus, headache and irritability. Papilledema, neuropsychological deficits; the latter may be minimal at the beginning or at first glance (slowly developing or long-standing hydrocephalus).

Measurement of head circumference: Mean of three values obtained in the largest frontooccipital plane.

a) Death (nearly 50 % within 10 years) or
b) Survival with variable loss of function.

1. Treated hydrocephalus with shunt insufficiency.
2. Hereditary macrocrania.
3. Infrequent pathologies such as congenital intracranial cysts, chronic subdural hematoma, achondroplasia, encephalopathies and metabolic disorders with cerebral involvement, catch-up growth of the head.

In case of an open fontanel: ultrasound as screening examination. In every case: CT or MRI. Examinations to discover the cause of the hydrocephalus.

Ventriculoperitoneal shunt. In selected cases: endoscopic ventriculostomy.

The prognosis depends on the cause of the hydrocephalus and the promptness of treatment. With treatment, normal global intelligence is observed in 2/3 of the cases, in isolated congenital hydrocephalus in 50 %. In 90 % there is a life-long shunt dependency with the possibility of shunt failures. In case of endoscopic ventriculostomy, similar follow-up times as in shunted patients are not yet available.