Etiology of hydrocephalus: 1, cerebrospinal fluid circulation pathway obstructed by the ventricular system or the outlet of the fourth ventricle; 2, cerebrospinal fluid circulation obstructed by the subarachnoid space; 3, cerebrospinal fluid circulation pathway obstructed by granular or venous return; 4, cerebrospinal fluid over-secretion or abnormal composition. Surgical treatment: 1, release the obstruction; 2, reduce cerebrospinal fluid secretion; 3, third ventriculostomy; 4, shunt surgery.