Hydrocephalus

===Shunt complications===
Examples of possible complications include shunt malfunction, shunt failure, and shunt infection, along with infection of the shunt tract following surgery (the most common reason for shunt failure is infection of the shunt tract). Although a shunt generally works well, it may stop working if it disconnects, becomes blocked (clogged) or infected, or it is outgrown. If this happens, the CSF begins to accumulate again and a number of physical symptoms develop (headaches, nausea, vomiting, [[photophobia]]/light sensitivity), some extremely serious, such as [[seizure]]s. The shunt failure rate is also relatively high (of the 40,000 surgeries performed annually to treat hydrocephalus, only 30% are a person's first surgery) and people not uncommonly have multiple shunt revisions within their lifetimes.<ref>{{Cite web | vauthors = Benner KW, Spellen S, Jeske A |title=Pharmacology of Shunt Infections |url=https://www.uspharmacist.com/article/pharmacology-of-shunt-infections |access-date=2022-05-18 |website=www.uspharmacist.com |language=en}}</ref>

Another complication can occur when CSF drains more rapidly than it is produced by the [[choroid plexus]], causing symptoms of listlessness, severe headaches, irritability, light sensitivity, auditory [[hyperesthesia]] (sound sensitivity), hearing loss,<ref name=":3" /> nausea, vomiting, [[dizziness]], [[Vertigo (medical)|vertigo]], [[migraines]], seizures, a change in personality, [[weakness]] in the arms or legs, [[strabismus]], and [[Diplopia|double vision]] to appear when the person is vertical. If the person lies down, the symptoms usually vanish quickly. A [[CT scan]] may or may not show any change in ventricle size, particularly if the person has a history of slit-like ventricles. Difficulty in diagnosing over-drainage can make treatment of this complication particularly frustrating for people and their families. Resistance to traditional [[analgesic]] pharmacological therapy may also be a sign of shunt overdrainage or failure.<ref>{{cite journal | vauthors = Nagahama Y, Peters D, Kumonda S, Vesole A, Joshi C, J Dlouhy B, Kawasaki H | title = Delayed diagnosis of shunt overdrainage following functional hemispherotomy and ventriculoperitoneal shunt placement in a hemimegalencephaly patient | journal = Epilepsy & Behavior Case Reports | volume = 7 | pages = 34–36 | date = 2017-01-24 | pmid = 28348960 | pmc = 5357741 | doi = 10.1016/j.ebcr.2016.12.003 }}</ref>

Following placement of a ventriculoperitoneal shunt there have been cases of a decrease in post-surgery hearing. It is presumed that the cochlea aqueduct is responsible for the decrease in hearing thresholds. The cochlea aqueduct has been considered as a probable channel where CSF pressure can be transmitted. Therefore, the reduced CSF pressure could cause a decrease in Perilymphatic pressure and cause secondary endolymphatic hydrops.<ref name=":3" /> In addition to the increased hearing loss, there have also been findings of resolved hearing loss after ventriculoperitoneal shunt placement, where there is a release of CSF pressure on the auditory pathways.<ref>{{cite journal | vauthors = Sammons VJ, Jacobson E, Lawson J | title = Resolution of hydrocephalus-associated sensorineural hearing loss after insertion of ventriculoperitoneal shunt | journal = Journal of Neurosurgery. Pediatrics | volume = 4 | issue = 4 | pages = 394–396 | date = October 2009 | pmid = 19795973 | doi = 10.3171/2009.4.PEDS09103 }}</ref>

The diagnosis of CSF buildup is complex and requires specialist expertise. Diagnosis of the particular complication usually depends on when the symptoms appear, that is, whether symptoms occur when the person is upright or in a prone position, with the head at roughly the same level as the feet.<ref>{{cite journal | vauthors = Krishnan SR, Arafa HM, Kwon K, Deng Y, Su CJ, Reeder JT, Freudman J, Stankiewicz I, Chen HM, Loza R, Mims M, Mims M, Lee K, Abecassis Z, Banks A, Ostojich D, Patel M, Wang H, Börekçi K, Rosenow J, Tate M, Huang Y, Alden T, Potts MB, Ayer AB, Rogers JA | display-authors = 6 | title = Continuous, noninvasive wireless monitoring of flow of cerebrospinal fluid through shunts in patients with hydrocephalus | journal = npj Digital Medicine | volume = 3 | issue = 1 | pages = 29 | date = 2020-03-06 | pmid = 32195364 | pmc = 7060317 | doi = 10.1038/s41746-020-0239-1 }}</ref>

Standardized protocols for inserting cerebral shunts have been shown to reduce shunt infections.<ref>{{cite journal | vauthors = Yang MM, Hader W, Bullivant K, Brindle M, Riva-Cambrin J | title = Calgary Shunt Protocol, an adaptation of the Hydrocephalus Clinical Research Network shunt protocol, reduces shunt infections in children | journal = Journal of Neurosurgery. Pediatrics | volume = 23 | issue = 5 | pages = 559–567 | date = February 2019 | pmid = 30797206 | doi = 10.3171/2018.10.PEDS18420 | s2cid = 73507028 }}</ref><ref>{{cite journal | vauthors = Kestle JR, Riva-Cambrin J, Wellons JC, Kulkarni AV, Whitehead WE, Walker ML, Oakes WJ, Drake JM, Luerssen TG, Simon TD, Holubkov R | display-authors = 6 | title = A standardized protocol to reduce cerebrospinal fluid shunt infection: the Hydrocephalus Clinical Research Network Quality Improvement Initiative | journal = Journal of Neurosurgery. Pediatrics | volume = 8 | issue = 1 | pages = 22–29 | date = July 2011 | pmid = 21721884 | pmc = 3153415 | doi = 10.3171/2011.4.PEDS10551 }}</ref> There is tentative evidence that preventative antibiotics may decrease the risk of shunt infections.<ref>{{cite journal | vauthors = Arts SH, Boogaarts HD, van Lindert EJ | title = Route of antibiotic prophylaxis for prevention of cerebrospinal fluid-shunt infection | journal = The Cochrane Database of Systematic Reviews | volume = 6 | pages = CD012902 | date = June 2019 | issue = 6 | pmid = 31163089 | pmc = 6548496 | doi = 10.1002/14651858.CD012902.pub2 }}</ref>