Hydrocephalus

===Communicating===
Communicating hydrocephalus, also known as nonobstructive hydrocephalus, is caused by impaired CSF reabsorption in the absence of any obstruction of CSF flow between the ventricles and subarachnoid space. This may be due to functional impairment of the [[arachnoid villi|arachnoidal granulations]] (also called arachnoid granulations or [[Pacchioni's granulations]]), which are located along the [[superior sagittal sinus]], and is the site of CSF reabsorption back into the venous system. Various neurologic conditions may result in communicating hydrocephalus, including subarachnoid/intraventricular hemorrhage, meningitis, and congenital absence of arachnoid villi. Scarring and fibrosis of the subarachnoid space following infectious, inflammatory, or hemorrhagic events can also prevent reabsorption of CSF, causing diffuse ventricular dilatation.<ref>{{Cite book| vauthors = Kaye A, Fox C, Diaz J |title=Essentials of Pediatric Anesthesiology |publisher=Cambridge University Press |year=2014 |pages=106 }}</ref>
[[File:Hydrocephalus_cranial_deformity_2.jpg|75px|thumbnail|right|An adult  with congenital hydrocephalus in the [[Philippines]]]]