Current Evidence Infections are a common cause of hydrocephalus in infants and children An estimated 1% of pediatric patients who survive bacterial meningitis, including gram-negative organisms (particularly Escherichia coli ) which occur most frequently in the neonatal age group, Haemophilus influenzae, Streptococcus pneumoniae, and group B streptococci, develop progressive hydrocephalus Other less common infectious causes of hydrocephalus in children include tuberculosis meningitis whose worldwide prevalence is rising, toxoplasmosis (or other members of the TORCH group) usually diagnosed in the perinatal period, and viral meningitis and encephalitis Head trauma has been recognized as a common cause of hydrocephalus About 4% of patients develop posttraumatic hydrocephalus requiring surgical CSF diversion True congenital hydrocephalus, meaning hydrocephalus present at birth, has an estimated incidence of 0.2 to 0.8/1,000 live births in the United States The incidence of congenital hydrocephalus associated with conditions, such as Dandy–Walker malformation (approximately 85% to 95%), myelomeningocele (approximately 80% to 90%), and IVH of prematurity (approximately 35%), is better established Midline arachnoid cysts and tumors related to the ventricular system can cause hydrocephalus by obstruction of the CSF pathways Tumors may also cause hydrocephalus by spilling blood or protein into the CSF, making the CSF more viscous, overloading the absorptive capacity of the arachnoid villi, and resulting in a communicating hydrocephalus Clinical Considerations Clinical Recognition Infants presenting symptoms include macrocephaly, bulging fontanelle, excessive irritability, lethargy, or vomiting Sunsetting of the eyes may be present This usually occurs later in the clinical course and consists of a spectrum of findings, including components of Parinaud syndrome (downward eye deviation, lid retraction, and convergenceretraction nystagmus) As raised ICP progresses, infants may develop bradycardia and/or apneic episodes In older children, the more common presenting symptoms include headache, nausea, or vomiting These symptoms tend to be more common in the mornings, when ICP is higher after having been recumbent overnight Other symptoms may include visual field deficits or double vision This