<prompt> Commonest cause of non-communicating hydrocephalus in children is -Congenital anomalyPerinatal injuryPost-inflammatory obstructionBrain tumors  <response>: Ans. is a i.e., Congenital anomaly Hydrocephalus o Hydrocephalus is characterized by an increased volume of CSF in association with progressive ventricular dilatation. o Hydrocephalus resulting from obstruction within the ventricular system is called obstructive or noncommunicating hydrocephalus. o Hydrocephalus resulting from obliteration of subarachnoid cisterns or malfunction of the arachnoid villi is called nonobstructive or communicating hydrocephalus. 