ABSTRACT
The term ‘hydrocephalus’ denotes the presence of an excessive amount of cerebrospinal fluid (CSF), which is usually under increased pressure with abnormal enlargement of the cerebral ventricles. It results from an imbalance between the production and absorption of CSF. It is most frequently caused by an intraventricular or extraventricular blockage in the normal circulation and absorption of CSF. Hydrocephalus may be classified as communicating and non-communicating. In noncommunicating hydrocephalus, the obstruction is in the ventricular system and may be caused by the ArnoldChiari malformation, aqueductal stenosis, neoplasm, hemorrhage or obstruction of the fourth ventricular outlet (Dandy-Walker malformation). The term ‘communicating hydrocephalus’ is used for situations where there is a free flow of CSF into the subarachnoid space; this may rarely be due to a choroid plexus papilloma, sometimes with the Arnold-Chiari malformation or more commonly following inflammatory conditions.
