hydrocephalus

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The clinical presentation of hydrocephalus varies with age as well as chronicity.

Infants:

Hydrocephalus is difficult to detect clinically before delivery, although enlarged ventricles can be spotted on ultrasonography as early as 18–20 weeks gestation.{{cite journal | vauthors = Kahle KT, Kulkarni AV, Limbrick DD, Warf BC | title = Hydrocephalus in children | language = English | journal = Lancet | volume = 387 | issue = 10020 | pages = 788–799 | date = February 2016 | pmid = 26256071 | doi = 10.1016/S0140-6736(15)60694-8 }} Since infants' skulls are not fully fused together at the cranial sutures yet, they have soft spots on their skulls known as open fontanelles.{{cite journal | vauthors = Lu VM, Shimony N, Jallo GI, Niazi TN | title = Infant Hydrocephalus | journal = Pediatrics in Review | volume = 45 | issue = 8 | pages = 450–460 | date = August 2024 | pmid = 39085190 | doi = 10.1542/pir.2023-006318 }} This anatomic characteristic means that infants' skulls can visibly grow in size when cerebrospinal fluid accumulates. Therefore, infants with hydrocephalus may present with an enlarged skull (or rapid growth in skull size), bulging fontanelles, or separated cranial sutures.{{cite journal | vauthors = Pindrik J, Schulz L, Drapeau A | title = Diagnosis and Surgical Management of Neonatal Hydrocephalus | journal = Seminars in Pediatric Neurology | volume = 42 | pages = 100969 | date = July 2022 | pmid = 35868728 | doi = 10.1016/j.spen.2022.100969 | series = Perinatal Neurology }} Parents or physicians may also note that the infant is more irritable or tired than normal. Other symptoms include seizures, inability to look upwards ("sunset eyes" or "setting sun" sign), and pauses in breathing. Infants may also present with lack of weight gain or failure to meet motor and developmental milestones.{{cite book | vauthors = Işık U, Özek MM | chapter = Clinical Findings of Children with Hydrocephalus |date=2018 | title = Pediatric Hydrocephalus |pages=1–19 | veditors = Cinalli G, Ozek MM, Sainte-Rose C | chapter-url=https://link.springer.com/referenceworkentry/10.1007/978-3-319-31889-9_46-1 |access-date=2025-01-23 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-319-31889-9_46-1 |isbn=978-3-319-31889-9 }} Imaging can be done to confirm the suspected diagnosis of hydrocephalus. In infants, the open fontanelles allow for use of head ultrasonography. This allows pediatricians to minimize radiation exposure and come up with a diagnosis quickly. If further information is needed, an MRI can be done.

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Of note, hydrocephalus in infants can occur as part of a syndrome, and therefore patients may present with other characteristic symptoms. An example of one such syndrome is the Walker-Warburg syndrome, in which patients may also have holoprosencephaly and several other cranial defects. The VACTERL disorders (vertebral anomalies, anal atresia, cardiac defects, tracheoesophageal fistula, renal and radial anomalies, and limb defects) may also include hydrocephalus, and can then be called VACTERL-H. Hydrocephalus can also occur as part of neurocutaneous disorders such as neurofibromatosis type I (NF I) and tuberous sclerosis. Lastly, patients with trisomy disorders (trisomy 9,19p, 13, 18, and 21) as well as triploidy have been noted to have hydrocephalus.File:Parinaud syndrome 2.jpgChildren:

In older children, the fontanelles are closed, so there is no visible change in head size. Since there is limited expansion of the skull, symptoms are more representative of the effects of increased intracranial pressure on a child's developing brain. The most common presenting features in this age group are memory and concentration issues as well as motor and gait abnormalities. Nausea, vomiting, and a tremor of the arms and legs are also common features in older children. Patients may also have papilledema (swelling of the optic disc), worsening vision, and difficulty looking upwards on examination. A key feature in this age group includes headaches, due to the intracranial hypertension caused by the increased CSF in the closed space of the skull. These headaches tend to occur early in the morning as patients have been in a horizontal position throughout the night, which increases ICP.

Symptoms that may occur in older children can include:{{cite journal | vauthors = Riveros Gilardi B, Muñoz López JI, Hernández Villegas AC, Garay Mora JA, Rico Rodríguez OC, Chávez Appendini R, De la Mora Malváez M, Higuera Calleja JA | title = Types of Cerebral Herniation and Their Imaging Features | journal = Radiographics | volume = 39 | issue = 6 | pages = 1598–1610 | date = October 2019 | pmid = 31589570 | doi = 10.1148/rg.2019190018 | s2cid = 203924869 }}

• Brief, shrill, high-pitched cry
• Changes in personality, memory, or the ability to reason or think
• Changes in facial appearance and eye spacing (craniofacial disproportion)
• Crossed eyes or uncontrolled eye movements
• Difficulty feeding
• Excessive sleepiness
• Headaches
• Irritability, poor temper control
• Loss of bladder control (urinary incontinence)
• Loss of coordination and trouble walking
• Muscle spasticity (spasm)
• Slow growth (child 0–5 years)
• Delayed milestones
• Failure to thrive
• Slow or restricted movement
• Vomiting{{Cite web |title=Hydrocephalus |url=https://www.nlm.nih.gov/medlineplus/ency/article/001571.htm |website=MedlinePlus |vauthors=Kaneshiro NK, Zieve D, Black B | collaboration = A.D.A.M. Editorial Team }}

Since increased intracranial pressure can damage the brain, thought and behavior may be negatively affected. Learning disabilities, including short-term memory loss, are common among those with hydrocephalus. Affected children tend to score better on verbal IQ than on performance IQ, a pattern which is thought to reflect the distribution of nerve damage to the brain. Hydrocephalus that is present from a young age can cause long-term problems with speech and language. Children can have trouble understanding complex and abstract concepts or difficulty retrieving stored information. They may also have a nonverbal learning disorder or spatial/perceptual disorders. Children affected by hydrocephalus may also have difficulty in understanding concepts within conversation. This is thought to be due to an inability to understand or interpret context. These children may tend to use words they know or have heard.{{cite journal | vauthors = Barnes MA, Dennis M | title = Discourse after early-onset hydrocephalus: core deficits in children of average intelligence | journal = Brain and Language | volume = 61 | issue = 3 | pages = 309–334 | date = February 1998 | pmid = 9570868 | doi = 10.1006/brln.1998.1843 | s2cid = 13336454 }}{{Citation |title=Hydrocephalus Associated with Spina Bifida: Specific Pathophysiology and Therapeutic Problems |vauthors=Oi S |date=1999 |work=Spina Bifida |pages=177–184 |publisher=Springer Japan |isbn=978-4-431-70260-3}} However, the severity of hydrocephalus can differ considerably between individuals, and some are of average or above-average intelligence. Aside from learning disabilities, a child with hydrocephalus may also have coordination and visual problems. They may reach puberty earlier than the average child (this is called precocious puberty). About one in four develops epilepsy.{{cite journal | vauthors = Parent AS, Teilmann G, Juul A, Skakkebaek NE, Toppari J, Bourguignon JP | title = The timing of normal puberty and the age limits of sexual precocity: variations around the world, secular trends, and changes after migration | journal = Endocrine Reviews | volume = 24 | issue = 5 | pages = 668–693 | date = October 2003 | pmid = 14570750 | doi = 10.1210/er.2002-0019 }}

Adults:

In adults, acute hydrocephalus can have many of the same signs and symptoms (headaches, vomiting, nausea, papilledema, sleepiness, or coma) of increased intracranial pressure (ICP) that are seen in children.{{cite journal | vauthors = Langner S, Fleck S, Baldauf J, Mensel B, Kühn JP, Kirsch M | title = Diagnosis and Differential Diagnosis of Hydrocephalus in Adults | language = de | journal = RoFo | volume = 189 | issue = 8 | pages = 728–739 | date = August 2017 | pmid = 28511266 | doi = 10.1055/s-0043-108550 }} Increased volumes of CSF can also result in hearing loss, including sensorineural hearing loss (SNHL).{{cite journal | vauthors = Dixon JF, Jones RO | title = Hydrocephalus-associated hearing loss and resolution after ventriculostomy | journal = Otolaryngology–Head and Neck Surgery | volume = 146 | issue = 6 | pages = 1037–1039 | date = June 2012 | pmid = 22166958 | doi = 10.1177/0194599811431234 | s2cid = 38240969 }} Hearing loss is a rare but well-known sequela of procedures resulting in CSF loss.{{cite journal | vauthors = Satzer D, Guillaume DJ | title = Hearing loss in hydrocephalus: a review, with focus on mechanisms | journal = Neurosurgical Review | volume = 39 | issue = 1 | pages = 13–24; discussion 25 | date = January 2016 | pmid = 26280639 | doi = 10.1007/s10143-015-0650-2 | s2cid = 24439157 }} Elevated ICP can also cause a portion of the brain to move out of place (uncal or tonsillar herniation), which can result in brain stem compression and possibly death.

By contrast, chronic dilatation (especially in the elderly population) may present in a more insidious manner. Hakim's triad of gait instability, urinary incontinence, and dementia is a relatively typical manifestation of a form of hydrocephalus known as normal pressure hydrocephalus (NPH). Focal neurological deficits may also occur, such as abducens nerve palsy and vertical gaze palsy (Parinaud syndrome due to compression of the quadrigeminal plate, where the neural centers coordinating the conjugated vertical eye movement are located). The symptoms depend on the cause of the blockage, the person's age, and how much brain tissue has been damaged by the swelling.

Hydrocephalus ex vacuo is a condition in which there is ventriculomegaly due to loss of brain volume which then results in a subsequent increase in CSF.{{cite journal | vauthors = Kim M, Park SW, Lee JY, Kim H, Rhim JH, Park S, Lee JY, Son H, Kim YK, Lee SH | title = Differences in Brain Morphology between Hydrocephalus Ex Vacuo and Idiopathic Normal Pressure Hydrocephalus | journal = Psychiatry Investigation | volume = 18 | issue = 7 | pages = 628–635 | date = July 2021 | pmid = 34265199 | pmc = 8328827 | doi = 10.30773/pi.2020.0352 }} This is most commonly seen in patients with neurodegenerative disorders such as Alzheimer's disease (due to hippocampal atrophy specifically).{{cite journal | vauthors = Apostolova LG, Green AE, Babakchanian S, Hwang KS, Chou YY, Toga AW, Thompson PM | title = Hippocampal atrophy and ventricular enlargement in normal aging, mild cognitive impairment (MCI), and Alzheimer Disease | journal = Alzheimer Disease and Associated Disorders | volume = 26 | issue = 1 | pages = 17–27 | date = January 2012 | pmid = 22343374 | pmc = 3286134 | doi = 10.1097/WAD.0b013e3182163b62 }} Therefore, the presenting symptoms of this condition will likely be those of Alzheimer's: memory loss, loss of language skills or comprehension (aphasia), inability to perform purposeful movements (apraxia), and inability to conduct activities of daily living independently. Hydrocephalus ex vacuo can also occur due to traumatic brain injuries or due to strokes.

Hydrocephalus can be caused by a combination of factors and is not fully understood. Any medical condition that interrupts the flow of cerebrospinal fluid (CSF) can cause this build-up of excess fluid. This occurs due to blocked pathways of cerebrospinal fluid (CSF), issues with CSF reabsorption, or increased CSF production.{{cite book | vauthors = Koleva M, De Jesus O | chapter = Hydrocephalus |date=2025 | title = StatPearls | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK560875/ |access-date=2025-01-15 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32809710 }}

Hydrocephalus can be classified as primary or secondary (acquired) based on the cause.{{cite journal | vauthors = Karimy JK, Reeves BC, Damisah E, Duy PQ, Antwi P, David W, Wang K, Schiff SJ, Limbrick DD, Alper SL, Warf BC, Nedergaard M, Simard JM, Kahle KT | title = Inflammation in acquired hydrocephalus: pathogenic mechanisms and therapeutic targets | journal = Nature Reviews. Neurology | volume = 16 | issue = 5 | pages = 285–296 | date = May 2020 | pmid = 32152460 | pmc = 7375440 | doi = 10.1038/s41582-020-0321-y }}

Primary hydrocephalus involves congenital, developmental, and genetic factors that lead to excess CSF build-up. Up to 50% of the causes of primary hydrocephalus are genetic.

Congenital hydrocephalus is defined by the presence of excess CSF at birth. It occurs due to a combination of factors, especially genetic causes prior to birth (meaning the fetus may develop hydrocephalus in utero during fetal development). The genes involved in congenital hydrocephalus involve aqueduct defects, development of the central nervous system, and cilia (involved in the movement and flow of CSF). 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 build up and hydrocephalus.{{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}}

Developmental disorders including neural-tube defects, arachnoid cysts, Dandy–Walker malformations, and Arnold–Chiari malformations can cause primary hydrocephalus. Dandy-walker malformations and Arnold-Chiari malformations lead to structural abnormalities in the brain, which disrupts the flow of CSF and causes hydrocephalus.{{cite book | vauthors = Hidalgo JA, Tork CA, Varacallo MA | chapter = Arnold-Chiari Malformation |date=2025 | title = StatPearls | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK431076/ |access-date=2025-01-23 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=28613730 }}{{cite book | vauthors = Zamora EA, Das JM, Ahmad T |chapter = Dandy-Walker Malformation |date=2025 | title = StatPearls |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK538197/ |access-date=2025-01-23 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30855785 }}

Neural tube defects are commonly caused by a deficiency of folic acid during pregnancy.{{cite book | vauthors = Singh R, Munakomi S | chapter = Embryology, Neural Tube |date=2025 | title = StatPearls | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK542285/ |access-date=2025-01-23 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=31194425 }} Spina bifida is a neural tube defect that involves defects in the development of the spine, and it can cause hydrocephalus. Myelomeningocele is the most severe type of spina bifida, involving an open spinal column and the exact mechanism of hydrocephalus involved in this condition is unclear.{{cite journal | vauthors = Norkett W, McLone DG, Bowman R | title = Current Management Strategies of Hydrocephalus in the Child With Open Spina Bifida | journal = Topics in Spinal Cord Injury Rehabilitation | volume = 22 | issue = 4 | pages = 241–246 | date = September 2016 | pmid = 29339864 | pmc = 5108507 | doi = 10.1310/sci2204-241 }}

Secondary hydrocephalus is acquired as a consequence of CNS infections, meningitis, brain tumors, head trauma, toxoplasmosis, or intracranial hemorrhage (subarachnoid or intraparenchymal).{{Cite web |title=Acquired Hydrocephalus {{!}} Conditions & Treatments {{!}} UCSF Benioff Children's Hospital |url=https://www.ucsfbenioffchildrens.org/conditions/acquired_hydrocephalus/ |access-date=2020-04-09 |website=www.ucsfbenioffchildrens.org}}

Intraventricular hemorrhage, or bleeding within the ventricles of the brain, leads to hydrocephalus in 51-89% of patients.{{cite journal | vauthors = Wang C, Bai J, He Q, Jiao Y, Zhang W, Huo R, Wang J, Xu H, Zhao S, Wu Z, Sun Y, Yu Q, Tang J, Zeng X, Yang W, Cao Y | title = Therapy management and outcome of acute hydrocephalus secondary to intraventricular hemorrhage in adults | journal = Chinese Neurosurgical Journal | volume = 10 | issue = 1 | pages = 17 | date = June 2024 | pmid = 38831472 | pmc = 11149196 | doi = 10.1186/s41016-024-00369-0 | doi-access = free }} This is because the blood in the ventricles blocks the regular flow of CSF, leading to build-up of excess CSFFile:Intracerebral hemorrhage.jpg and intraventricular hemorrhage with hydrocephalus shown on CT scan{{cite journal | vauthors = Yadav YR, Mukerji G, Shenoy R, Basoor A, Jain G, Nelson A | title = Endoscopic management of hypertensive intraventricular haemorrhage with obstructive hydrocephalus | journal = BMC Neurology | volume = 7 | pages = 1 | date = January 2007 | pmid = 17204141 | pmc = 1780056 | doi = 10.1186/1471-2377-7-1 | doi-access = free }}]]Normal pressure hydrocephalus (NPH) most often occurs in elderly patients with symptoms including gait disturbance, urinary incontinence, and cognitive issues.{{cite journal | vauthors = Passos-Neto CE, Lopes CC, Teixeira MS, Studart Neto A, Spera RR | title = Normal pressure hydrocephalus: an update | journal = Arquivos de Neuro-Psiquiatria | volume = 80 | issue = 5 Suppl 1 | pages = 42–52 | date = May 2022 | pmid = 35976308 | pmc = 9491444 | doi = 10.1590/0004-282x-anp-2022-s118 }} It is commonly divided into two categories, idiopathic NPH (with unknown cause) and secondary NPH (due to trauma, hemorrhage, etc.).

Hydrocephalus can also be caused by overproduction of CSF (relative obstruction) (e.g., choroid plexus papilloma, villous hypertrophy).{{Cite book |url=https://books.google.com/books?id=2kv-Z-L5UUAC&pg=PT353 |title=Otology, Neurotology, and Lateral Skull Base Surgery: An Illustrated Handbook |vauthors=Adunka O, Buchman C |date=11 October 2010 |publisher=Thieme |isbn=978-3-13-149621-8 |pages=353– |access-date=12 August 2013 |archive-url=https://web.archive.org/web/20140705102607/http://books.google.com/books?id=2kv-Z-L5UUAC&pg=PT353 |archive-date=5 July 2014 |url-status=live}}{{cite journal | vauthors = Nimjee SM, Powers CJ, McLendon RE, Grant GA, Fuchs HE | title = Single-stage bilateral choroid plexectomy for choroid plexus papilloma in a patient presenting with high cerebrospinal fluid output | journal = Journal of Neurosurgery. Pediatrics | volume = 5 | issue = 4 | pages = 342–345 | date = April 2010 | pmid = 20367337 | doi = 10.3171/2009.10.peds08454 }}

Brain atrophy or breakdown in elderly patients or patients with conditions like Parkinson's or Alzheimer's can lead to acquired hydrocephalus.{{cite journal | vauthors = Hladky SB, Barrand MA | title = Regulation of brain fluid volumes and pressures: basic principles, intracranial hypertension, ventriculomegaly and hydrocephalus | journal = Fluids and Barriers of the CNS | volume = 21 | issue = 1 | pages = 57 | date = July 2024 | pmid = 39020364 | pmc = 11253534 | doi = 10.1186/s12987-024-00532-w | doi-access = free }} This is likely because the breakdown of brain cells leads to ventriculomegaly (enlargement of ventricles) and increased space for CSF to fill.

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Hydrocephalus is due to an imbalance between the amount of cerebrospinal fluid (CSF) produced and the amount reabsorbed (or removed from the ventricular system).{{cite journal | vauthors = Bramall AN, Anton ES, Kahle KT, Fecci PE | title = Navigating the ventricles: Novel insights into the pathogenesis of hydrocephalus | journal = eBioMedicine | volume = 78 | pages = 103931 | date = April 2022 | pmid = 35306341 | pmc = 8933686 | doi = 10.1016/j.ebiom.2022.103931 }} The purpose of cerebrospinal fluid is to provide mechanical support, nutrients, and remove waste from the central nervous system.{{cite journal | vauthors = Liu XY, Song X, Czosnyka M, Robba C, Czosnyka Z, Summers JL, Yu HJ, Gao GY, Smielewski P, Guo F, Pang MJ, Ming D | title = Congenital hydrocephalus: a review of recent advances in genetic etiology and molecular mechanisms | journal = Military Medical Research | volume = 11 | issue = 1 | pages = 54 | date = August 2024 | pmid = 39135208 | pmc = 11318184 | doi = 10.1186/s40779-024-00560-5 | doi-access = free }} In a person without hydrocephalus, CSF continuously circulates through the brain, its ventricles and the spinal cord and is continuously drained away into the circulatory system. Alternatively, the condition may result from an overproduction of the CSF, from a congenital malformation blocking normal drainage of the fluid, or from complications of head injuries or infections.{{Cite web |date=August 2005 |title=Hydrocephalus Fact Sheet |url=http://www.ninds.nih.gov/disorders/hydrocephalus/detail_hydrocephalus.htm |archive-url=https://web.archive.org/web/20160727231854/http://www.ninds.nih.gov/disorders/hydrocephalus/detail_hydrocephalus.htm |archive-date=2016-07-27 |website=National Institute of Neurological Disorders and Stroke}}

The choroid plexus, located in the lateral ventricles, forms the majority of CSF (believed to be around 70-80%). The ependymal lining of the ventricular system, the subarachnoid space, and the blood-brain-barrier forms the rest.

CSF flows through the ventricular system through the following pathway:{{cite book | vauthors = Leinonen V, Vanninen R, Rauramaa T | chapter = Cerebrospinal fluid circulation and hydrocephalus | title = Handbook of Clinical Neurology | volume = 145 | pages = 39–50 | date = 2018 | pmid = 28987185 | doi = 10.1016/b978-0-12-802395-2.00005-5 | access-date = 2025-01-15 | isbn = 978-0-12-802395-2 | chapter-url = https://linkinghub.elsevier.com/retrieve/pii/B9780128023952000055 | publisher = Elsevier }}

Lateral Ventricles → Interventricular Foramen of Monro → Third Ventricle → Cerebral Aqueduct → Fourth Ventricle

The CSF then exits the fourth ventricle through the median aperture and lateral aperture. It goes into the subarachnoid space or central canal of the spinal cord. Then, it is absorbed by the vili of arachnoid granulations into the blood circulation.

There have also been recent theories and studies exploring the drainage of CSF.{{cite journal | vauthors = Proulx ST | title = Cerebrospinal fluid outflow: a review of the historical and contemporary evidence for arachnoid villi, perineural routes, and dural lymphatics | journal = Cellular and Molecular Life Sciences | volume = 78 | issue = 6 | pages = 2429–2457 | date = March 2021 | pmid = 33427948 | pmc = 8004496 | doi = 10.1007/s00018-020-03706-5 }} One theory involves the drainage of CSF into the lymphatic vessel system. The lymphatic vessel system clears proteins and fluid throughout the body, but whether they are involved in CSF drainage within the brain is controversial and not yet clear. Lymphatic vessels in the dura mater is a possible site of CSF drainage.

Cilia plays a role in the flow of CSF. Cilia are long microtubules on the cell membranes of many cells, including ependymal cells (which line the ventricular system). Some genetic causes of congenital hydrocephalus have been linked to issues with cilia.

When the cerebrospinal fluid builds up, it causes compression of the brain, which leads to the symptoms of convulsions, intellectual disability, and epileptic seizures. These signs occur sooner in adults because their skulls are no longer able to expand to based on the increasing fluid volume. Fetuses, infants, and young children with hydrocephalus have head enlargement, excluding the face, because the pressure of the fluid causes the individual skull bones—which have yet to fuse—to bulge outward at their juncture points.{{Cite book |title=Physical diagnosis |vauthors=Cabot RC |date=1919 |publisher=William Wood and Company |edition=7th |location=New York |page=5 |via=Google Books}}

A rare complication of hydrocephalus is hearing loss. There are a few possible mechanisms involved in hearing loss in hydrocephalus.{{cite journal | vauthors = Satzer D, Guillaume DJ | title = Hearing loss in hydrocephalus: a review, with focus on mechanisms | journal = Neurosurgical Review | volume = 39 | issue = 1 | pages = 13–24; discussion 25 | date = January 2016 | pmid = 26280639 | doi = 10.1007/s10143-015-0650-2 }} The cochlear aqueduct connects the perilymphatic space of the inner ear with the subarachnoid space of the posterior cranial fossa.{{cite journal | vauthors = Lim HW, Shim BS, Yang CJ, Kim JH, Cho YH, Cho YS, Kong DS, Koo JW, Han JH, Chung JW | title = Hearing loss following ventriculoperitoneal shunt in communicating hydrocephalus patients: a pilot study | journal = The Laryngoscope | volume = 124 | issue = 8 | pages = 1923–1927 | date = August 2014 | pmid = 24318317 | doi = 10.1002/lary.24553 | s2cid = 24667376 }} Because of the delicate relationship between pressure and hearing, hearing loss may also be caused after a shunt is placed to treat hydrocephalus.{{cite journal | vauthors = Verma M, Singh J, Singh I, Kakkar V, Yadav SP, George JS | title = To Evaluate the Pre and Post Shunt Sensorineural Hearing Loss in Hydrocephalus Patients | journal = Indian Journal of Otolaryngology and Head and Neck Surgery | volume = 71 | issue = Suppl 2 | pages = 1314–1319 | date = November 2019 | pmid = 31750171 | pmc = 6841878 | doi = 10.1007/s12070-018-1372-x }}

CSF can accumulate within the ventricles, this condition is called internal hydrocephalus and may result in increased CSF pressure. The production of CSF continues, even when the passages that normally allow it to exit the brain are blocked. Consequently, fluid builds inside the brain, causing pressure that dilates the ventricles and compresses the nervous tissue. Compression of the nervous tissue usually results in irreversible brain damage. If the skull bones are not completely ossified when the hydrocephalus occurs, the pressure may also severely enlarge the head. The cerebral aqueduct may be blocked at the time of birth or may become blocked later in life because of a tumor growing in the brainstem.{{Cite web |date=2017-12-07 |title=Hydrocephalus: Causes, symptoms, and treatments |url=https://www.medicalnewstoday.com/articles/181727 |access-date=2022-05-18 |website=www.medicalnewstoday.com |language=en}}

The classification of communicating vs. noncommunicating hydrocephalus are often used to describe the types of hydrocephalus. These terms describe the nonobstructive vs. obstructive mechanisms of the excess CSF build-up.

In communicating hydrocephalus, there is no obstruction of CSF flow. Instead, there is either an increased production of CSF or difficulty reabsorbing CSF.{{cite journal | vauthors = Mirkhaef SA, Harbaugh L, Nagra G | title = Hydrocephalus: A Review of Etiology-Driven Treatment Strategies | journal = Cureus | volume = 16 | issue = 9 | pages = e68516 | date = September 2024 | pmid = 39364470 | pmc = 11448269 | doi = 10.7759/cureus.68516 | doi-access = free }} Reabsorption occurs at the arachnoid granulations, so issues with reabsorption can occur because of arachnoid granulation impairment. There is also evidence of the lymphatic system being involved with reabsorption, so impairments of this system can also lead to excess CSF. Damage to these reabsorption sites are commonly post-hemorrhage or post-infection (such as meningitis). Scarring and fibrosis of the subarachnoid space following infectious, inflammatory, or hemorrhagic events can also prevent reabsorption of CSF, causing hydrocephalus.{{Cite book |title=Essentials of Pediatric Anesthesiology |vauthors=Kaye A, Fox C, Diaz J |publisher=Cambridge University Press |year=2014 |pages=106}}

Normal pressure hydrocephalus (NPH) is a form of chronic communicating hydrocephalus, with enlarged cerebral ventricles and intermittently increased cerebrospinal fluid pressure.{{cite book | vauthors = Das JM, Biagioni MC | chapter = Normal Pressure Hydrocephalus |date=2025 | title = StatPearls | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK542247/ |access-date=2025-01-21 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=31194404 }} The symptoms include dementia, gait changes, and urinary incontinence. It is diagnosed with continuous intraventricular pressure recordings (over 24 hours or even longer) because instant measurements can show normal pressure values. Dynamic compliance studies may be also helpful. Altered compliance (elasticity) of the ventricular walls, as well as increased viscosity of the cerebrospinal fluid, may play a role in the pathogenesis.{{cite journal | vauthors = Martin BA, Loth F | title = The influence of coughing on cerebrospinal fluid pressure in an in vitro syringomyelia model with spinal subarachnoid space stenosis | journal = Cerebrospinal Fluid Research | volume = 6 | issue = 1 | pages = 17 | date = December 2009 | pmid = 20043856 | pmc = 2806373 | doi = 10.1186/1743-8454-6-17 | doi-access = free }}

File:Hydrocephalus_cranial_deformity_2.jpg]]

In noncommunicating hydrocephalus, there is obstruction to the CSF flow. Examples of common causes include hemorrhage, tumor, traumatic brain injury that disrupt the flow, leading to build-up of CSF in the brain.

File:Khidmat Masy Hydrocephalus (19042957419).jpg

File:Hydrocephalus Shunt Child.png

Hydrocephalus is treated through surgery by creating a way for the excess fluid to drain away. An external ventricular drain (EVD), also known as an extraventricular drain or ventriculostomy, provides relief in the short term.{{cite journal | vauthors = Navaei AA, Hanaei S, Habibi Z, Jouibari MF, Heidari V, Naderi S, Nejat F | title = Controlled Trial to Compare Therapeutic Efficacy of Endoscopic Third Ventriculostomy Plus Choroid Plexus Cauterization with Ventriculoperitoneal Shunt in Infants with Obstructive Hydrocephalus | journal = Asian Journal of Neurosurgery | volume = 13 | issue = 4 | pages = 1042–1047 | date = December 2018 | pmid = 30459864 | pmc = 6208245 | doi = 10.4103/ajns.AJNS_63_17 | doi-access = free }} In the long term, some people will need any of the various types of cerebral shunts. It involves the placement of a ventricular catheter (a tube made of silastic) into the cerebral ventricles. This creates a way to bypass the flow obstruction/malfunctioning arachnoidal granulations. The excess fluid drains into other body cavities where it can be resorbed. Most shunts drain the fluid into the peritoneal cavity (ventriculoperitoneal shunt). Other shunts drain the fluid into the right atrium (ventriculoatrial shunt), pleural cavity (ventriculopleural shunt), and gallbladder.{{cite journal | vauthors = Bue EL, Morello A, Bellomo J, Bradaschia L, Lacatena F, Colonna S, Fiumefreddo A, Stieglitz L, Regli L, Lanotte MM, Garbossa D, Cofano F | title = Ventriculoatrial shunt remains a safe surgical alternative for hydrocephalus: a systematic review and meta-analysis | journal = Scientific Reports | volume = 14 | issue = 1 | pages = 18460 | date = August 2024 | pmid = 39117692 | pmc = 11310213 | doi = 10.1038/s41598-024-62366-8 | bibcode = 2024NatSR..1418460B }}

{{Further|topic=the non-invasive diagnostic medical device|ShuntCheck}}

A shunt system can also be placed in the lumbar space of the spine. This allows the excess fluid to be redirected to the peritoneal cavity (lumbar-peritoneal shunt).{{cite journal | vauthors = Ho YJ, Chiang WC, Huang HY, Lin SZ, Tsai ST | title = Effectiveness and safety of ventriculoperitoneal shunt versus lumboperitoneal shunt for communicating hydrocephalus: A systematic review and meta-analysis with trial sequential analysis | journal = CNS Neuroscience & Therapeutics | volume = 29 | issue = 3 | pages = 804–815 | date = March 2023 | pmid = 36650662 | pmc = 9928545 | doi = 10.1111/cns.14086 }} Another treatment for obstructive hydrocephalus is an endoscopic third ventriculostomy (ETV). This surgery creates an opening in the floor of the third ventricle so that CSF flows directly to the basal cisterns. This treatment can shortcut any obstruction like aqueductal stenosis. This may or may not be appropriate based on individual anatomy. Some infants can be treated with ETV and choroid plexus cauterization. Choroid plexus cauterization reduces the amount of cerebrospinal fluid produced by the brain. The technique, known as ETV/CPC, was pioneered in Uganda by neurosurgeon Benjamin Warf and is now in use in several U.S. hospitals.{{Cite web |date=22 April 2015 |title=An American surgeon pioneers surgery for kids in Uganda that helps kids in the US |url=http://www.pri.org/stories/2015-04-27/american-surgeon-pioneers-surgery-kids-uganda-helps-kids-us |url-status=live |archive-url=https://web.archive.org/web/20160302012700/http://www.pri.org/stories/2015-04-27/american-surgeon-pioneers-surgery-kids-uganda-helps-kids-us |archive-date=2016-03-02 |access-date=2016-02-10 |website=Public Radio International}}{{cite journal | vauthors = Burton A | title = Infant hydrocephalus in Africa: spreading some good news | journal = The Lancet. Neurology | volume = 14 | issue = 8 | pages = 789–790 | date = August 2015 | pmid = 26091960 | doi = 10.1016/S1474-4422(15)00138-6 | s2cid = 35920581 }}

External hydrocephalus is generally seen in infants. It involves enlarged fluid spaces or subarachnoid spaces outside of the brain. The most common sign is a head circumference above the 90th percentile. In most cases, no other signs or symptoms are reported.{{cite journal | vauthors = Khosroshahi N, Nikkhah A | title = Benign Enlargement of Subarachnoid Space in Infancy: "A Review with Emphasis on Diagnostic Work-Up" | journal = Iranian Journal of Child Neurology | volume = 12 | issue = 4 | pages = 7–15 | date = Autumn 2018 | pmid = 30279704 | pmc = 6160631 }} Rarely reported symptoms include a tense anterior fontanel, developmental delay, seizures, irritability, and vomiting.{{cite journal | vauthors = Zahl SM, Egge A, Helseth E, Wester K | title = Benign external hydrocephalus: a review, with emphasis on management | journal = Neurosurgical Review | volume = 34 | issue = 4 | pages = 417–432 | date = October 2011 | pmid = 21647596 | pmc = 3171652 | doi = 10.1007/s10143-011-0327-4 }} Usually, this condition is benign. It resolves spontaneously by two to three years of age.{{Cite book |url=https://books.google.com/books?id=0TC9Cns4Qz8C&q=Greenberg+handbook+of+neurosurgery+external+hydrocephalus&pg=PA307 |title=Handbook of Neurosurgery |vauthors=Greenberg MS |date=2010-02-15 |publisher=Thieme |isbn=9781604063264 |archive-url=https://web.archive.org/web/20230708022539/https://books.google.com/books?id=0TC9Cns4Qz8C&pg=PA307 |archive-date=2023-07-08 |url-status=live}} Thus, it usually does not need insertion of a shunt. If surgical treatment is required, a ventriculoperitoneal shunt is usually preferred. Other treatment options include using medications like acetazolamide. The condition can be diagnosed and monitored with brain sonography and CT/MRI. These tests and a good medical history can help to identify external hydrocephalus from similar conditions: subdural hemorrhages or symptomatic chronic extra-axial fluid collections which are accompanied by vomiting, headaches, and seizures.{{Cite web |title=Subdural Hematomas in the Elderly: The Great Neurological Imitator {{!}} 2000-03-01 {{!}} AHC Media: Continuing Medical Education Publishing {{!}} Relias Media - Continuing Medical Education Publishing |url=https://www.reliasmedia.com/articles/44955-subdural-hematomas-in-the-elderly-the-great-neurological-imitator |access-date=2022-05-17 |website=www.reliasmedia.com}}{{cite journal | vauthors = Ravid S, Maytal J | title = External hydrocephalus: a probable cause for subdural hematoma in infancy | journal = Pediatric Neurology | volume = 28 | issue = 2 | pages = 139–141 | date = February 2003 | pmid = 12699866 | doi = 10.1016/s0887-8994(02)00500-3 }}

Shunt surgery is one of the most common procedures in pediatric neurosurgery. Significant advances in shunt technology and surgical approaches have been made over the years. However, the lifetime risk for a revision surgery of a ventriculoperitoneal shunt in pediatric patients can reach up to 80%.{{cite journal | vauthors = Tervonen J, Leinonen V, Jääskeläinen JE, Koponen S, Huttunen TJ | title = Rate and Risk Factors for Shunt Revision in Pediatric Patients with Hydrocephalus-A Population-Based Study | journal = World Neurosurgery | volume = 101 | pages = 615–622 | date = May 2017 | pmid = 28213196 | doi = 10.1016/j.wneu.2017.02.030 }} Shunt failure rates are also high. Of the 40,000 surgeries performed annually for hydrocephalus, only 30% are a person’s first surgery. Many patients require multiple revisions during their lives.{{Cite web |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 |vauthors=Benner KW, Spellen S, Jeske A}} Common complications requiring revision include:

1. overdrainage of cerebrospinal fluid
2. obstrucion of the valve or catheter
3. infection
4. catheter disconnection/migration{{cite journal | vauthors = Hasanain AA, Abdullah A, Alsawy MF, Soliman MA, Ghaleb AA, Elwy R, Ezzat AA, Al Menabbawy A, Marei AA, Abd El Razik B, El Hamaky MI, Schroeder HW, Fleck S, El Damaty A, Marx S, Nowak S, Baldauf J, Zohdi A, El Refaee EA | title = Incidence of and Causes for Ventriculoperitoneal Shunt Failure in Children Younger Than 2 Years: A Systematic Review | journal = Journal of Neurological Surgery. Part A, Central European Neurosurgery | volume = 80 | issue = 1 | pages = 26–33 | date = January 2019 | pmid = 30508865 | doi = 10.1055/s-0038-1669464 }}

If shunt failure occurs, the cerebrospinal fluid begins to accumulate again. This can cause a number of physical symptoms develop (headaches, nausea, vomiting, photophobia/light sensitivity), some extremely serious, such as seizures. Patient factors that are associated with shunt failure includes the cause of the hydrocephalus, prematurity, male sex, spina bifida, epilepsy, severity of ventricular dilation, ethnicity, and age <1 year. The diagnosis of CSF buildup is complex and requires specialist expertise. Diagnosis can depend on whether symptoms occur. For example, whether symptoms occur when the person is upright or in a prone position (lying down) with the head at roughly the same level as the feet.{{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 | 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 }}

Overdrainage of cerebrospinal fluid occurs when the fluid drains more rapidly than it is produced by the choroid plexus. The rate of overdrainage is estimated to be about 10% to 12% within 6.5 years after shunt placement.{{cite journal | vauthors = Pudenz RH, Foltz EL | title = Hydrocephalus: overdrainage by ventricular shunts. A review and recommendations | journal = Surgical Neurology | volume = 35 | issue = 3 | pages = 200–212 | date = March 1991 | pmid = 1996449 | doi = 10.1016/0090-3019(91)90072-H }} Signs and symptoms of overdrainage includes:

• listlessness
• severe headaches
• irritability
• light sensitivity
• auditory hyperesthesia (sound sensitivity)
• hearing loss
• nausea
• vomiting
• dizziness
• vertigo
• migraines
• seizures
• a change in personality
• weakness in the arms or legs,
• strabismus
• double vision (to appear when the person is vertical or standing)

If the person lies down, the symptoms usually vanish quickly. Resistance to traditional analgesic pharmacological therapy may also be a sign of shunt overdrainage or failure.{{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 }} A CT scan may or may not show any change in ventricle size, particularly if the person has a history of slit-like ventricles. It can be challenging to diagnose over-drainage. This can make treatment of overdrainage particularly frustrating for people and their families. However, monitoring the intracranial pressure in combination with radiological findings has been found to be a useful tool for identifying cases of overdrainage. Prevention of this complication includes using adjustable pressure valves and integrated gravitational units. To alleviate the symptoms, a lumbar puncture or external lumbar or ventricular drainage could be used. To prevent chronic overdrainage, a valve exchange is recommended.{{cite journal | vauthors = Ros B, Iglesias S, Linares J, Cerro L, Casado J, Arráez MA | title = Shunt Overdrainage: Reappraisal of the Syndrome and Proposal for an Integrative Model | journal = Journal of Clinical Medicine | volume = 10 | issue = 16 | pages = 3620 | date = August 2021 | pmid = 34441916 | pmc = 8396927 | doi = 10.3390/jcm10163620 | doi-access = free }}

Shunt obstruction is the most common cause of shunt failure. The shunt can be obstructed at the catheter or the valve itself. Cases of shunt obstruction would present with similar symptoms to untreated hydrocephalus (headaches, nausea, lethargy, etc.). It can be caused by tissue, bacteria, or kinking of the catheter. Diagnosis is usually made by shunt tapping and imaging studies like CT. Treatment involves replacing or flushing the shunt to address the cause of the obstruction and restore flow through the catheter.{{Cite journal | vauthors = Paff M, Alexandru-Abrams D, Muhonen M, Loudon W |date=2018-09-01 |title=Ventriculoperitoneal shunt complications: A review |journal=Interdisciplinary Neurosurgery |volume=13 |pages=66–70 |doi=10.1016/j.inat.2018.04.004 |issn=2214-7519|doi-access=free }}

The rate of initial shunt infection ranges from 3.6 to 12.6% The signs and symptoms of shunt infection are variable, but the most common include headache, nausea, fever, swelling, and lethargy. Shunt infections are most commonly diagnosed by culturing the cerebrospinal fluid. According to studies, the most common cause of infection are bacteria, followed by fungi. The bacterial Staphylococcal species, especially coagulase-negative Staphylococcus and Staphylococcus aureus, is responsible for almost 2/3 of shunt infections.{{cite journal | vauthors = Simon TD, Schaffzin JK, Stevenson CB, Willebrand K, Parsek M, Hoffman LR | title = Cerebrospinal Fluid Shunt Infection: Emerging Paradigms in Pathogenesis that Affect Prevention and Treatment | journal = The Journal of Pediatrics | volume = 206 | pages = 13–19 | date = March 2019 | pmid = 30528757 | pmc = 6389391 | doi = 10.1016/j.jpeds.2018.11.026 }} It is believed that these organisms are introduced to the cerebrospinal fluid at the time of surgery. In the case of shunt infection, it is recommended to remove the shunt. place an external ventricular drain, and then place a new shunt.{{cite journal | vauthors = Robinson JL, Freire D, Bialy L | title = Treatment strategies for cerebrospinal shunt infections: a systematic review of observational studies | journal = BMJ Open | volume = 10 | issue = 12 | pages = e038978 | date = December 2020 | pmid = 33303443 | pmc = 7733168 | doi = 10.1136/bmjopen-2020-038978 }} Current research is dedicated to methods to prevent such infections from occurring. Using antibiotics or different shunt hardware to prevent bacterial growth is being studied. The efficacy of more vigilant shunt surveillance is also being studied. Standardized protocols for inserting cerebral shunts have been shown to reduce shunt infections.{{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 = May 2019 | pmid = 30797206 | doi = 10.3171/2018.10.PEDS18420 | s2cid = 73507028 }}{{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 | 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 }} There is tentative evidence that preventative antibiotics may decrease the risk of shunt infections.{{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 | issue = 6 | pages = CD012902 | date = June 2019 | pmid = 31163089 | pmc = 6548496 | doi = 10.1002/14651858.CD012902.pub2 }}

Shunt migration is a relatively uncommon complication that requires a shunt revision. The most common sites that the shunt catheter can migrate to include the scrotum (30.67% of cases), followed by through the anus (22% of cases). Less common sites include the large intestine, small intestine, stomach, and oral cavity. Signs and symptoms vary depending on the site of migration. For example, intestinal migrations may present with abdominal pain, fever, and vomiting, especially if it perforates the bowel. Anal migration often presents with no symptoms.{{cite journal | vauthors = Datta D, Sekar A, Guruprasad N, Bansal S | title = Shunt Migration in Children: A Patient Level Systematic Review of Risk Factors and Outcome | journal = Neurology India | volume = 70 | issue = 5 | pages = 1780–1786 | date = September 2022 | pmid = 36352565 | doi = 10.4103/0028-3886.359270 | doi-access = free }}{{cite journal | vauthors = Adel K, Fayçal A, Toufik B, Abdelhalim M | title = Bowel perforation and anal ventriculoperitoneal shunt migration: A systematic review | journal = Journal of Taibah University Medical Sciences | volume = 19 | issue = 2 | pages = 263–269 | date = April 2024 | pmid = 38234714 | pmc = 10792256 | doi = 10.1016/j.jtumed.2023.12.002 }}

Following placement of a VP 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. This could cause secondary endolymphatic hydrops. 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.{{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 }}

It is estimated that congenital hydrocephalus occurs in 8.5 out of 10,000 live births globally. The disease burden is more concentrated in Africa, Asia, and South America.{{cite journal | vauthors = Gili JA, López-Camelo JS, Nembhard WN, Bakker M, de Walle HE, Stallings EB, Kancherla V, Contiero P, Dastgiri S, Feldkamp ML, Nance A, Gatt M, Martínez L, Canessa MA, Groisman B, Hurtado-Villa P, Källén K, Landau D, Lelong N, Morgan M, Arteaga-Vázquez J, Pierini A, Rissmann A, Sipek A, Szabova E, Wertelecki W, Zarante I, Canfield MA, Mastroiacovo P | title = Analysis of early neonatal case fatality rate among newborns with congenital hydrocephalus, a 2000-2014 multi-country registry-based study | journal = Birth Defects Research | volume = 114 | issue = 12 | pages = 631–644 | date = July 2022 | pmid = 35633200 | pmc = 9288486 | doi = 10.1002/bdr2.2045 | first12 = Amy | first13 = Miriam | first10 = Saeed | first11 = Marcia L. | first14 = Laura | first15 = María Aurora | first9 = Paolo }} A study in 2019 estimated that there are 180,000 childhood hydrocephalus cases from the African continent per year. It also reported 90,000 cases from Southeast Asia and the Western Pacific. Congenital hydrocephalus was found to be associated with many factors. The health of the affected individual's mother is one factor. Exposure to medications in the prenatal period such as antibiotics is another factor. Low socioeconomic status is also a factor. In adults that are 18–64 years-old, about 11 in 100,000 cases of hydrocephalus is estimated. For adults over 65 years of age, 175 in 100,000 cases is estimated.{{cite journal | vauthors = Tullberg M, Toma AK, Yamada S, Laurell K, Miyajima M, Watkins LD, Wikkelsø C | title = Classification of Chronic Hydrocephalus in Adults: A Systematic Review and Analysis | journal = World Neurosurgery | volume = 183 | pages = 113–122 | date = March 2024 | pmid = 38143036 | doi = 10.1016/j.wneu.2023.12.094 | doi-access = free }}

File:Vimont Traite de Phrenologie 022.jpg

In the pre-historic area, there were various paintings or artifacts depicting children or adults with macrocephaly (large head) or clinical findings of hydrocephalus.{{Cite book | vauthors = Cinalli G |title=Pediatric Hydrocephalus |date=2019 |publisher=Springer International Publishing |isbn=978-3-319-27248-1 | veditors = Cinalli G, Özek MM, Sainte-Rose C |location=Cham |page=3 |language=en |chapter=History of Hydrocephalus and Its Surgical Treatment |doi=10.1007/978-3-319-27250-4 |chapter-url=http://link.springer.com/10.1007/978-3-319-27250-4 |s2cid=128359318}} The earliest scientific description of hydrocephalus was written by the ancient Greek physician, Hippocrates. He coined the word 'hydrocephalus' from the Greek ὕδωρ, hydōr meaning 'water' and κεφαλή, kephalē meaning 'head'. A more accurate description was later given by the Roman physician Galen in the second century AD.

The first clinical description of an operative procedure for hydrocephalus appears in the Al-Tasrif (1,000 AD). This was contributed by the Arab surgeon Abulcasis. He described the evacuation of superficial intracranial fluid in hydrocephalic children.{{cite journal | vauthors = Aschoff A, Kremer P, Hashemi B, Kunze S | title = The scientific history of hydrocephalus and its treatment | journal = Neurosurgical Review | volume = 22 | issue = 2–3 | pages = 67–93; discussion 94–5 | date = October 1999 | pmid = 10547004 | doi = 10.1007/s101430050035 | s2cid = 10077885 }} In his chapter on neurosurgical disease, he described that infantile hydrocephalus was caused by mechanical compression. Specifically, he wrote:

{{blockquote|The skull of a newborn baby is often full of liquid, either because the matron has compressed it excessively or for other, unknown reasons. The volume of the skull then increases daily, so that the bones of the skull fail to close. In this case, we must open the middle of the skull in three places, make the liquid flow out, then close the wound and tighten the skull with a bandage.}}

File:Hydrocephalus-baby.jpg

In the 17th century, Isbrand de Diemerbroeck proposed that the enlargement of an 18-month-old child's head was due to unhealthy diet. This diet would cause thick fluids to travel from the intestines to the skull. He proposed using a poultice and laxative to decrease the amount of fluids in the body. If those methods failed, he recommended a skin puncture to remove the fluid. In 1744, Claude-Nicolas Le Cat, a French surgeon, performed a ventricular puncture to treat a 3-month old with hydrocephalus. He attempted to perform this surgery a second time, but the patient did not survive. Also during the 18th century, an English physician named Michael Underwood reported the symptoms associated with hydrocephalus. He described vomiting, fever, dilated pupils, sensitivity to light, and diplopia. He also noted that patients eventually fell into a deep coma and died.

In 1881, Carl Wernicke pioneered sterile ventricular puncture and external drainage of CSF for the treatment of hydrocephalus. This occurred a few years after the landmark study of Retzius and Key. In 1891, Heinrich Quincke first described using a lumbar puncture to drain excess spinal fluid. This eventually led to investigating permanent treatment methods. This would require developing a continuous drain to treat hydrocephalus.{{cite journal | vauthors = Demerdash A, Singh R, Loukas M, Tubbs RS | title = A historical glimpse into treating childhood hydrocephalus | journal = Child's Nervous System | volume = 32 | issue = 3 | pages = 405–407 | date = March 2016 | pmid = 25707482 | doi = 10.1007/s00381-015-2652-3 }}{{cite journal | vauthors = Lifshutz JI, Johnson WD | title = History of hydrocephalus and its treatments | language = en-US | journal = Neurosurgical Focus | volume = 11 | issue = 2 | pages = E1 | date = August 2001 | pmid = 16602674 | doi = 10.3171/foc.2001.11.2.2 }} In 1893, Jan MIkulicz-Radecki used a permanent shunt to drain CSF successfully. It wasn't until the 20th century that hydrocephalus remained an intractable condition. This was when cerebral shunt and other neurosurgical treatment modalities were developed. In the early 20th century, the role of the arachnoid villi in absorbing cerebrospinal fluid was confirmed by Harvey Cushing. He recommended draining the fluid into the retroperitoneal space rather than the scalp. He was the first to attempt to create a shunt to the external jugular vein using a transplanted vein from the patient's father. In the 1950s, the invention of radiotracers allowed for scientists to trace the flow of cerebrospinal fluid. These findings were critical for shaping future therapies and treatments of hydrocephalus.

The first hydrocephalus shunt was placed in 1956. For the next 30 years, advances in shunt material and design were made, such as development of a valve system. Additionally, the invention of prenatal ultrasound made diagnosis of fetal hydrocephalus possible around the 1970s and 1980s. In the 1980s and 1990s, it was found that an endoscope could be used to more accurately place ventricular catheters. The advent of endoscopic procedures also resulted in endoscopic third ventriculostomies being used more commonly. This is an alternative method from shunt placement to treat hydrocephalus.

The word hydrocephalus is from the Greek {{Langx|grc|text=ὕδωρ|label=none|translit=hydōr}} meaning 'water' and {{Langx|grc|text=κεφαλή|label=none|translit=kephalē}} meaning 'head'. Other names for hydrocephalus include "water on the brain", a historical name, and "water baby syndrome".{{Cite book |url=https://books.google.com/books?id=H9KsNAWbcMcC&q=hydrocephalus+%22water+baby%22&pg=PA53 |title=Death, Modernity, and the Body: Sweden 1870-1940 |vauthors=Åhrén E |publisher=University of Rochester Press |year=2009 |isbn=9781580463126 |location=Rochester, New York |pages=53 |language=en}}

File:Hydrocephalus ribbon two tone blue.jpg]]

There are many organizations that advocate for hydrocephalus patients and promote research about its treatments. The Hydrocephalus Association was founded as a family support group in 1983 by parents of children with hydrocephalus. It has since expanded to a non-profit patient advocacy group, and has invested over $14 million in research since 2009.{{Cite web |title=Learn About the Hydrocephalus Association {{!}} Mission & Vision |url=https://www.hydroassoc.org/about-us/ |access-date=2025-01-23 |website=www.hydroassoc.org |language=en-US}} The National Hydrocephalus Foundation, also started by parents of a child with hydrocephalus, is a non-profit organization established in 1979.{{Cite web |title=About Us – Hydrocephalus education, support and resources {{!}} NHFOnline.org |url=https://nhfonline.org/about-us/ |access-date=2025-01-23 |language=en-US}} The Pediatric Hydrocephalus Foundation was founded in 2005 for similar purposes.{{Cite web | title = About PHF |url=http://www.hydrocephaluskids.org/wordpress/?page_id=2 |access-date=2025-01-23 |website=www.hydrocephaluskids.org}}

September was designated National Hydrocephalus Awareness Month in July 2009 by the U.S. Congress in {{USBill|111|hres|373}}. The resolution campaign is due in part to the advocacy work of the Pediatric Hydrocephalus Foundation. Prior to July 2009, no awareness month for this condition had been designated.

• Ice hockey player Colby Cave had acute obstructive hydrocephalus due to a colloid cyst.{{Cite web |date=April 11, 2020 |title=Oilers forward Colby Cave dies after suffering brain bleed |url=https://www.cbc.ca/sports/hockey/nhl/edmonton-oilers-colby-cave-1.5529808 |access-date=4 May 2021 |website=CBC}}
• Author Sherman Alexie, born with the condition, wrote about it in his semi-autobiographical junior fiction novel The Absolutely True Diary of a Part-Time Indian.{{Cite web | vauthors = Williams ST |title=Man of many tribes |url=http://www.startribune.com/entertainment/books/11435616.html |url-status=live |archive-url=https://web.archive.org/web/20130520004510/http://www.startribune.com/entertainment/books/11435616.html |archive-date=2013-05-20 |access-date=2014-01-29 |publisher=Star Tribune}}
• Prince William, Duke of Gloucester (1689–1700), probably contracted meningitis at birth, which resulted in this condition.{{cite book | vauthors = Somerset A | author-link1 = Anne Somerset (historian) |title=Queen Anne: the politics of passion | date = 2012 |publisher= HarperCollins |location=London |isbn=978-0-00-720376-5 |page=116}}
• Emperor Ferdinand I of Austria (1793–1875) became emperor in 1835 despite various health issues including hydrocephalus and epilepsy.{{Cite web |title=Waiting for the Executioner in 1848 Austria Regime change and the case for clemency |url=https://ces.fas.harvard.edu/news/2021/11/waiting-for-the-executioner-in-1848-austria-regime-change-and-the-case-for-clemency |access-date=2025-01-23 |website=Minda de Gunzburg Center for European Studies |language=en}}
• Masato Kudo, a professional soccer player, died of hydrocephalus on October 21, 2022.
• Danny Bonaduce, a TV and radio personality, revealed that he would be undergoing surgery for hydrocephalus that was impeding his ability to walk properly in 2023{{Cite web |date=2023-06-06 |title=Danny Bonaduce's "Mystery Illness" Explained {{!}} Hydrocephalus Association |url=https://www.hydroassoc.org/danny-bonaduces-mystery-illness-explained/ |access-date=2025-01-23 |website=www.hydroassoc.org |language=en-US}}
• King Charles II of Spain, known as "El Hechizado" (the Bewitched), is thought to have suffered from many diseases, including pituitary hormone deficiency, renal tubular acidosis, Klinefelter syndrome, fragile X syndrome, and hydrocephalus{{cite journal | vauthors = Turliuc MD, Cucu AI, Perciaccante A, Tosolini G, De Luca S, Costachescu B, Costea CF | title = Hydrocephalus of King Charles II of Spain, the Bewitched King | journal = European Neurology | volume = 81 | issue = 1–2 | pages = 76–78 | date = 2019-05-21 | pmid = 31112979 | doi = 10.1159/000500719 | doi-access = free }}
• King Bhumibol Adulyadej of Thailand was treated for hydrocephalus in 2015{{Cite news |date=2015-08-11 |title=Thai King Bhumibol recovering from 'water on brain' |url=https://www.bbc.com/news/world-asia-33858442 |access-date=2025-01-23 |work=BBC News |language=en-GB}}
• Billy Joel announced May 22, 2025 he is cancelling his concerts and being treated for the condition. https://www.nytimes.com/2025/05/23/arts/music/billy-joel-brain-disorder-nph.html?smid=nytcore-ios-share&referringSource=articleShare

{{Clear}}

{{reflist}}

{{Commons category|Hydrocephalus}}

• [http://thejns.org/toc/pedsup/14/Suppl Guidelines for pediatric hydrocephalus]

{{Medical resources

| ICD10={{ICD10|G|91||g|90}}, {{ICD10|Q|03||q|00}}

| ICD9={{ICD9|331.3}}, {{ICD9|331.4}}, {{ICD9|741.0}}, {{ICD9|742.3}}

| OMIM=236600

| DiseasesDB=6123

| MedlinePlus=001571

| eMedicineSubj=neuro

| eMedicineTopic=161

| MeSH=D006849

}}

{{CNS diseases of the nervous system}}

{{Congenital malformations and deformations of nervous system}}

{{Authority control}}

Category:Congenital disorders of nervous system

Category:Disorders causing seizures

Category:Pediatrics

Category:Ventricular system

Category:Wikipedia medicine articles ready to translate

Category:Wikipedia neurology articles ready to translate