Goals of Treatment Hydrocephalus can present in an acute or subacute fashion Most children with hydrocephalus will need surgical treatment CLINICAL PEARLS AND PITFALLS Hydrocephalus has been categorized as obstructive (noncommunicating) or nonobstructive (communicating) Most cases of pediatric hydrocephalus, even congenital, have a delayed diagnosis Hydrocephalus is rarely a stand-alone diagnosis and is often secondary to additional pathology Hydrocephalus is the excess accumulation of cerebrospinal fluid (CSF), usually as the result of obstruction in CSF absorption, resulting in raised ICP CSF is produced by the choroid plexus which is located within all four ventricles in the brain Under normal conditions, the CSF exits the fourth ventricle to circulate in the subarachnoid space to be absorbed back into the venous system largely through arachnoid villi located at the superior sagittal sinus Obstructive (or noncommunicating) hydrocephalus does not allow for the CSF to leave the ventricular system, and nonobstructive (or communicating) hydrocephalus occurs when the obstruction to CSF absorption lies outside the ventricular system in the subarachnoid space or at the arachnoid villi Common causes of obstructive hydrocephalus include stenosis of the cerebral aqueduct (from congenital causes, midbrain tumors, following hemorrhage or infection) and posterior fossa tumors Common causes of nonobstructive hydrocephalus include scarring of the subarachnoid space and arachnoid villi following intraventricular hemorrhage (IVH) in premature infants or meningitis In congenital conditions such myelomeningocele, the cause of hydrocephalus is likely multifactorial and may involve both obstructive and nonobstructive elements Genetic causes are a less likely cause, including X-linked aqueductal stenosis and primary ciliopathies