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{{Hydrocephalus}}
{{Hydrocephalus}}
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{{CMG}} {{AE}} {{SAH}}
'''Associate Editor-In-Chief:''' [[User:zorkun|Cafer Zorkun]] M.D., PhD.,{{KD}}
==Overview==
==Overview==
Hydrocephalus is classified based upon the underlying cause such as impaired [[cerebrospinal fluid]] ([[CSF]]) flow, impaired CSF reabsorption, or excessive CSF production.
Hydrocephalus is classified based upon the underlying cause such as impaired [[cerebrospinal fluid]] ([[CSF]]) flow, impaired [[CSF]] reabsorption, or excessive [[CSF]] production.
==Classification Scheme==
==Classification ==
Based on its underlying mechanisms, hydrocephalus can be classified into
*Based on its underlying mechanisms, hydrocephalus can be classified into:<ref name="pmid21928019">{{cite journal |vauthors=Rekate HL |title=A consensus on the classification of hydrocephalus: its utility in the assessment of abnormalities of cerebrospinal fluid dynamics |journal=Childs Nerv Syst |volume=27 |issue=10 |pages=1535–41 |date=October 2011 |pmid=21928019 |pmc=3175041 |doi=10.1007/s00381-011-1558-y |url=}}</ref><ref>{{cite journal|doi=10.1186/1743-8454-5-2.}}</ref>
* '''Communicating''' (non-obstructive)
**Communicating (non-obstructive).
* '''Non-communicating''' (obstructive).  
**Non-communicating (obstructive).  


Both communicating and non-communicating forms can be either  
*Both communicating and non-communicating forms can be either:
* '''Congenital'''
**Congenital.
* '''Acquired'''.
**Acquired.


=== Communicating hydrocephalus ===
==== === 1. Communicating hydrocephalus === ====
'''Communicating hydrocephalus''', also known as '''non-obstructive hydrocephalus''',
*The mechanism of hydrocephalus is given below:<ref name="pmid21928019">{{cite journal |vauthors=Rekate HL |title=A consensus on the classification of hydrocephalus: its utility in the assessment of abnormalities of cerebrospinal fluid dynamics |journal=Childs Nerv Syst |volume=27 |issue=10 |pages=1535–41 |date=October 2011 |pmid=21928019 |pmc=3175041 |doi=10.1007/s00381-011-1558-y |url=}}</ref><ref>{{cite journal|doi=10.1186/1743-8454-5-2.}}</ref>
* It is caused by impaired cerebrospinal fluid resorption in the absence of any CSF-flow obstruction.
**It is caused by impaired [[cerebrospinal fluid]] resorption in the absence of any [[CSF]]-flow obstruction.
* It has been theorized that this is due to functional impairment of the arachnoid granulations,
**It has been theorized that this is due to functional impairment of the [[arachnoid granulations]].
* Arachnoid granulations are located along the [[superior sagittal sinus]] and is the site of  cerebrospinal fluid resorption back into the venous system.
**[[Arachnoid granulations]] are located along the [[superior sagittal sinus]] and is the site of  [[cerebrospinal fluid]] resorption back into the [[venous]] system.
* Various neurologic conditions may result in communicating hydrocephalus, including
**Various [[Neurological|neurologic]] conditions may result in communicating hydrocephalus, including:
# subarachnoid/intraventricular hemorrhage
**[[Subarachnoid space|Subarachnoid]]/[[intraventricular hemorrhage]].
# [[meningitis]]
**[[Meningitis]].
# [[Chiari malformation]]
**[[Chiari malformation]].
# congenital absence of [[arachnoid villi|arachnoidal granulations]] ('''Pacchioni's granulations''').
**[[Congenital]] absence of [[arachnoid villi|arachnoidal granulations]] (Pacchioni's granulations).
'''Sub-types of communicating hydrocephalus:'''


*'''[[Normal pressure hydrocephalus]]''' (NPH) is a particular form of '''communicating hydrocephalus''', characterized by enlarged cerebral ventricles, with only intermittently elevated cerebrospinal fluid pressure. The diagnosis of NPH can be established only with the help of continuous intraventricular pressure recordings (over 24 hours or even longer), since more often than not, instant measurements yield 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 of '''[[normal pressure hydrocephalus]]'''.
'''(a) [[Normal pressure hydrocephalus]]''' (NPH):
{{main|normal pressure hydrocephalus}}
* NPH is a particular form of communicating hydrocephalus, characterized by enlarged [[Cerebral ventricle|cerebral ventricles]], with only intermittently elevated [[Cerebrospinal fluid|cerebrospinal fluid pressure]].
*'''''Hydrocephalus ex vacuo''''' also refers to an enlargement of cerebral ventricles and subarachnoid spaces, and is usually due to '''brain [[atrophy]]''' (as it occurs in [[dementia]]s), post-[[traumatic brain injury|traumatic brain injuries]] and even in some psychiatric disorders, such as [[schizophrenia]]. As opposed to hydrocephalus, this is a '''compensatory enlargement'''of the CSF-spaces in response to '''brain [[parenchyma]] loss''' - it '''is not''' the result of increased CSF pressure.
* The [[diagnosis]] of NPH can be established only with the help of continuous [[intraventricular]] pressure recordings (over 24 hours).


=== Non-communicating hydrocephalus ===
==== (b) Hydrocephalus ex vacuo: ====
Non-communicating hydrocephalus, or '''obstructive hydrocephalus''', is caused by a CSF-flow obstruction (either due to external compression or intraventricular mass lesions).
* It refers to an enlargement of [[cerebral ventricle]]
*[[Interventricular foramina|'''Foramen of Monro''']] obstruction may lead to dilation of one or, if large enough (e.g., in colloid cyst), both lateral ventricles.
* Hydrocephalus ex vacuo occurs as a result of compensatory enlargement of the [[CSF]]-spaces in response to brain [[parenchyma]] loss.
*'''The [[Cerebral aqueduct|aqueduct of Sylvius]]''', normally narrow to begin with, may be obstructed by a number of genetically or acquired lesions (e.g., atresia, ependymitis, hemorrhage, tumor) and lead to dilatation of both lateral ventricles as well as the third ventricle.
*'''[[Fourth ventricle]]''' obstruction will lead to dilatation of the aqueduct as well as the lateral and third ventricles.
*'''The [[foramina of Luschka]] and [[Median aperture|foramen of Magendie]]''' may be obstructed due to congenital failure of opening (e.g., [[Dandy-Walker malformation]]).
*'''The [[subarachnoid space]] surrounding the brainstem''' may also be obstructed due to inflammatory or hemorrhagic fibrosing meningitis, leading to widespread dilatation, including the fourth ventricle.


===Congenital hydrocephalus ===
==== 2. Non-communicating hydrocephalus ====
The cranial bones 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
*Non-communicating hydrocephalus, or obstructive hydrocephalus, is caused by a [[CSF]]-flow obstruction (either due to external compression or intraventricular mass lesions) which leads to:<ref name="pmid21928019" /><ref>{{cite journal|doi=10.1186/1743-8454-5-2.}}</ref>
* intraventricular matrix hemorrhages in premature infants
**[[Interventricular foramina|Foramen of Monro]] obstruction may lead to dilation of one or, if large enough (e.g., in colloid cyst), both lateral ventricles.
* infections
**The [[Cerebral aqueduct|aqueduct of Sylvius]], normally narrow to begin with, may be obstructed by a number of genetically or acquired lesions (e.g., atresia, ependymitis, hemorrhage, tumor) and lead to dilatation of both lateral ventricles as well as the third ventricle.
* type II [[Arnold-Chiari malformation]]
**[[Fourth ventricle]] obstruction will lead to dilatation of the aqueduct as well as the lateral and third ventricles.
* aqueduct atresia and stenosis
**The [[foramina of Luschka]] and [[Median aperture|foramen of Magendie]] may be obstructed due to congenital failure of opening (e.g., [[Dandy-Walker malformation]]).
* Dandy-Walker malformation.
**The [[subarachnoid space]] surrounding the brainstem may also be obstructed due to inflammatory or hemorrhagic fibrosing meningitis, leading to widespread dilatation, including the fourth ventricle.
{{main|Arnold-Chiari malformation|Dandy-Walker malformation}}
About 80-90% of fetuses or newborn infants with [[spina bifida]] - often associated with [[meningocele]] or [[myelomeningocele]]- develop hydrocephalus.


=== Acquired hydrocephalus ===
==== Congenital hydrocephalus ====
This condition is acquired as a consequence of CNS-
*The [[cranial]] bones 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:<ref name="pmid21928019" /><ref name=":0">{{cite journal|doi=10.1186/1743-8454-5-2.}}</ref>
* [[infections]]
**Intraventricular matrix [[hemorrhages]] in [[premature infants]]
* [[meningitis]]
**[[Infections]]
* [[brain tumors]]
**Type II [[Arnold-Chiari malformation]]
* [[traumatic brain injury|head trauma]]
**Aqueduct atresia and stenosis
* [[stroke|intracranial hemorrhage]] (subarachnoid or intraparenchymal) and is usually extremely painful for the patient.
**[[Dandy-Walker malformation|Dandy-Walker malformation.]]
**About 80-90% of fetuses or newborn infants with [[spina bifida]] which are often associated with [[meningocele]] or [[myelomeningocele]], develops hydrocephalus.
 
==== Acquired hydrocephalus ====
The acquired condition is the result of<ref name=":0" /><ref name="pmid21928019" />:
* [[Infections]].
* [[Meningitis]].
* [[Brain tumors]].
* [[Traumatic brain injury|Head trauma]].
* [[Stroke|Intracranial hemorrhage]] (subarachnoid or intraparenchymal) and is usually extremely painful for the patient.
{| class="wikitable"
|+
!Communicating (non-obstructive)
!Non-Communicating (non-obstructive)
!Congenital hydrocephalus
!Acquired hydrocephalus
|-
|subarachnoid/intraventricular hemorrhage
|colloid cyst [[Interventricular foramina|'''Foramen of Monro''']] obstruction
|intraventricular matrix hemorrhages in premature infants
|[[infections]]
|-
|[[meningitis]]
|atresia of  '''[[Cerebral aqueduct|aqueduct of Sylvius]]'''
|infections
|[[meningitis]]
|-
|[[Chiari malformation]]
|ependymitis
|type II [[Arnold-Chiari malformation]]
|[[brain tumors]]
|-
|congenital absence of [[arachnoid villi|arachnoidal granulations]]
|hemorrhage
|aqueduct atresia and stenosis
|[[traumatic brain injury|head trauma]]
|-
|'''[[Normal pressure hydrocephalus]]'''
|tumor
|Dandy-Walker malformation.
|Subarachnoid hemorrhage
|-
|'''brain [[atrophy]]'''
|[[Dandy-Walker malformation]]
|[[spina bifida]]
|
|-
|post-[[traumatic brain injury|traumatic]] brain injuries
|hemorrhagic fibrosing meningitis
|[[meningocele]]
|
|-
|psychiatric disorders, such as [[schizophrenia]]
|
|[[myelomeningocele]]
|
|}


== References ==
== References ==
{{reflist|2}}
{{reflist|2}}
[[Category:Neurological disorders]]
[[Category:Greek loanwords]]
[[Category:Disease]]
[[Category:Neurology]]
[[Category:Grammar]]
[[Category:Grammar]]
[[Category:Pediatrics]]
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Syed Ahsan Hussain, M.D.[2]

Overview

Hydrocephalus is classified based upon the underlying cause such as impaired cerebrospinal fluid (CSF) flow, impaired CSF reabsorption, or excessive CSF production.

Classification

  • Based on its underlying mechanisms, hydrocephalus can be classified into:[1][2]
    • Communicating (non-obstructive).
    • Non-communicating (obstructive).
  • Both communicating and non-communicating forms can be either:
    • Congenital.
    • Acquired.

=== 1. Communicating hydrocephalus ===

Sub-types of communicating hydrocephalus:

(a) Normal pressure hydrocephalus (NPH):

(b) Hydrocephalus ex vacuo:

  • It refers to an enlargement of cerebral ventricle
  • Hydrocephalus ex vacuo occurs as a result of compensatory enlargement of the CSF-spaces in response to brain parenchyma loss.

2. Non-communicating hydrocephalus

  • Non-communicating hydrocephalus, or obstructive hydrocephalus, is caused by a CSF-flow obstruction (either due to external compression or intraventricular mass lesions) which leads to:[1][4]
    • Foramen of Monro obstruction may lead to dilation of one or, if large enough (e.g., in colloid cyst), both lateral ventricles.
    • The aqueduct of Sylvius, normally narrow to begin with, may be obstructed by a number of genetically or acquired lesions (e.g., atresia, ependymitis, hemorrhage, tumor) and lead to dilatation of both lateral ventricles as well as the third ventricle.
    • Fourth ventricle obstruction will lead to dilatation of the aqueduct as well as the lateral and third ventricles.
    • The foramina of Luschka and foramen of Magendie may be obstructed due to congenital failure of opening (e.g., Dandy-Walker malformation).
    • The subarachnoid space surrounding the brainstem may also be obstructed due to inflammatory or hemorrhagic fibrosing meningitis, leading to widespread dilatation, including the fourth ventricle.

Congenital hydrocephalus

Acquired hydrocephalus

The acquired condition is the result of[5][1]:

Communicating (non-obstructive) Non-Communicating (non-obstructive) Congenital hydrocephalus Acquired hydrocephalus
subarachnoid/intraventricular hemorrhage colloid cyst Foramen of Monro obstruction intraventricular matrix hemorrhages in premature infants infections
meningitis atresia of aqueduct of Sylvius infections meningitis
Chiari malformation ependymitis type II Arnold-Chiari malformation brain tumors
congenital absence of arachnoidal granulations hemorrhage aqueduct atresia and stenosis head trauma
Normal pressure hydrocephalus tumor Dandy-Walker malformation. Subarachnoid hemorrhage
brain atrophy Dandy-Walker malformation spina bifida
post-traumatic brain injuries hemorrhagic fibrosing meningitis meningocele
psychiatric disorders, such as schizophrenia myelomeningocele

References

  1. 1.0 1.1 1.2 1.3 1.4 Rekate HL (October 2011). "A consensus on the classification of hydrocephalus: its utility in the assessment of abnormalities of cerebrospinal fluid dynamics". Childs Nerv Syst. 27 (10): 1535–41. doi:10.1007/s00381-011-1558-y. PMC 3175041. PMID 21928019.
  2. . doi:10.1186/1743-8454-5-2. Check |doi= value (help). Missing or empty |title= (help)
  3. . doi:10.1186/1743-8454-5-2. Check |doi= value (help). Missing or empty |title= (help)
  4. . doi:10.1186/1743-8454-5-2. Check |doi= value (help). Missing or empty |title= (help)
  5. 5.0 5.1 . doi:10.1186/1743-8454-5-2. Check |doi= value (help). Missing or empty |title= (help)


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