Hydrocephalus

==Cause==

===Congenital===
[[File:Hydrocephalus with sunset eyes.jpg|thumb|A one-year-old girl with hydrocephalus showing "sunset eyes", before shunt surgery]]
[[File:Kleeblattschadel Syndrome 3.jpg|thumb|Hydrocephalus in a child with kleeblattschadel]]
Congenital hydrocephalus is present in the infant prior to birth, meaning the fetus developed hydrocephalus ''[[Uterus|in utero]]'' during [[fetal development]]. The most common cause of congenital hydrocephalus is aqueductal stenosis, which occurs when the narrow passage between the third and fourth ventricles in the brain is blocked or too narrow to allow sufficient cerebral spinal fluid to drain. Fluid accumulates in the upper ventricles, causing hydrocephalus.<ref>{{cite web |title=The Hydrocephalus Association |url=http://www.hydroassoc.org |archive-url=https://web.archive.org/web/20060820210617/http://www.hydroassoc.org/ |archive-date=2006-08-20}}</ref>

Other causes of congenital hydrocephalus include [[neural tube|neural-tube]] defects, [[arachnoid cyst]]s, [[Dandy–Walker syndrome]], and [[Arnold–Chiari malformation]].
The [[cranial bone]]s fuse by the end of the third year of life. For head enlargement to occur, hydrocephalus must occur before then. The causes are usually genetic, but can also be acquired and usually occur within the first few months of life, which include intraventricular matrix hemorrhages in [[premature infants]], infections, type II Arnold-Chiari malformation, aqueduct atresia and stenosis, and Dandy-Walker malformation.<ref>{{Citation | vauthors = Nagra G, Del Bigio MR |title=Pathology of Pediatric Hydrocephalus |date=2018 |url=https://doi.org/10.1007/978-3-319-31889-9_43-1 |work=Pediatric Hydrocephalus |pages=1–25 | veditors = Cinalli G, Ozek MM, Sainte-Rose C |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-319-31889-9_43-1 |isbn=978-3-319-31889-9 |s2cid=81899785 |access-date=2022-05-17 }}</ref><ref>{{Cite web |title=Congenital Hydrocephalus - an overview {{!}} ScienceDirect Topics |url=https://www.sciencedirect.com/topics/nursing-and-health-professions/congenital-hydrocephalus |access-date=2022-05-17 |website=www.sciencedirect.com}}</ref> Hydrocephalus can also occur with [[craniosynostosis]], being a constant feature of [[Kleeblattschaedel|kleeblattschadel]] and frequently seen in syndomic cases (mostly in [[Crouzon syndrome]]).<ref>{{Cite journal |last1=Cinalli |first1=G. |last2=Sainte-Rose |first2=C. |last3=Kollar |first3=E. M. |last4=Zerah |first4=M. |last5=Brunelle |first5=F. |last6=Chumas |first6=P. |last7=Arnaud |first7=E. |last8=Marchac |first8=D. |last9=Pierre-Kahn |first9=A. |last10=Renier |first10=D. |date=February 1998 |title=Hydrocephalus and craniosynostosis |url=https://pubmed.ncbi.nlm.nih.gov/9452225/ |journal=Journal of Neurosurgery |volume=88 |issue=2 |pages=209–214 |doi=10.3171/jns.1998.88.2.0209 |issn=0022-3085 |pmid=9452225}}</ref> Hydrocephalus has also been seen in cases of [[congenital syphilis]].<ref>{{cite journal | vauthors = Arnold SR, Ford-Jones EL | title = Congenital syphilis: A guide to diagnosis and management | journal = Paediatrics & Child Health | volume = 5 | issue = 8 | pages = 463–469 | date = November 2000 | pmid = 20177559 | pmc = 2819963 | doi = 10.1093/pch/5.8.463 }}</ref>

In newborns and toddlers with hydrocephalus, the head circumference is enlarged rapidly and soon surpasses the 97th percentile. Since the skull bones have not yet firmly joined, bulging, firm [[anterior fontanelle|anterior]] and [[posterior fontanelle]]s may be present even when the person is in an upright position.{{citation needed|date=May 2022}}

The infant exhibits fretfulness, poor feeding, and frequent vomiting. As the hydrocephalus progresses, [[torpor]] sets in, and infants show lack of interest in their surroundings. Later on, their upper eyelids become retracted and their eyes are turned downwards ("sunset eyes") (due to hydrocephalic pressure on the [[mesencephalic tegmentum]] and [[paralysis]] of upward gaze). Movements become weak and the arms may become [[Tremor|tremulous]]. Papilledema is absent, but vision may be reduced. The head becomes so enlarged that they eventually may be bedridden.<ref>{{Cite web  |title=What You Should Know About Macrocephaly |url=https://www.webmd.com/brain/what-you-should-know-about-macrocephaly |access-date=2022-05-17 |website=[[WebMD]] |language=en}}</ref>

About 80–90% of fetuses or newborn infants with [[spina bifida]]—often associated with [[meningocele]] or [[myelomeningocele]]—develop hydrocephalus.<ref>{{cite web |url=http://www.spinabifidamoms.com/english/about.html |title=Spina Bifida |publisher=Spinabifidamoms.com |access-date=2014-01-29 |url-status=dead |archive-url=https://web.archive.org/web/20131101014750/http://www.spinabifidamoms.com/english/about.html |archive-date=2013-11-01}}</ref>

===Acquired===
This condition is acquired as a consequence of CNS [[infections]], [[meningitis]], [[brain tumors]], [[traumatic brain injury|head trauma]], [[toxoplasmosis]], or [[stroke|intracranial hemorrhage]] (subarachnoid or intraparenchymal), and is usually painful.<ref>{{Cite web|url=https://www.ucsfbenioffchildrens.org/conditions/acquired_hydrocephalus/|title=Acquired Hydrocephalus {{!}} Conditions & Treatments {{!}} UCSF Benioff Children's Hospital|website=www.ucsfbenioffchildrens.org|access-date=2020-04-09}}</ref>