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{{Hydrocephalus}}
{{Hydrocephalus}}
{{CMG}}; '''Associate Editor-In-Chief:''' [[User:zorkun|Cafer Zorkun]] M.D., PhD.,Kalsang Dolma, MBBS
{{CMG}}; {{AE}}{{SAH}}
==Overview==
==Overview==
 
Hydrocephalus mostly results due to CSF flow [[obstruction]], hindering the free passage of cerebrospinal fluid through the ventricular system and it can also be caused by overproduction of cerebrospinal fluid (relative obstruction).
 
==Pathophysiology==
 
* The pathophysiology of hydrocephalus is given below:.<ref>[http://www.ninds.nih.gov/disorders/hydrocephalus/detail_hydrocephalus.htm "Hydrocephalus Fact Sheet"], National Institute of Neurological Disorders and Stroke. (August 2005).</ref><ref name="pmid2757806">{{cite journal |vauthors=Strandgaard S, Paulson OB |title=Cerebral blood flow and its pathophysiology in hypertension |journal=Am. J. Hypertens. |volume=2 |issue=6 Pt 1 |pages=486–92 |date=June 1989 |pmid=2757806 |doi= |url=}}</ref><ref name="pmid6516910">{{cite journal |vauthors=Strandgaard S, Andersen GS, Ahlgreen P, Nielsen PE |title=Visual disturbances and occipital brain infarct following acute, transient hypotension in hypertensive patients |journal=Acta Med Scand |volume=216 |issue=4 |pages=417–22 |date=1984 |pmid=6516910 |doi= |url=}}</ref><ref name="pmid641549">{{cite journal |vauthors=Enevoldsen EM, Jensen FT |title=Autoregulation and CO2 responses of cerebral blood flow in patients with acute severe head injury |journal=J. Neurosurg. |volume=48 |issue=5 |pages=689–703 |date=May 1978 |pmid=641549 |doi=10.3171/jns.1978.48.5.0689 |url=}}</ref><ref name="pmid7452330">{{cite journal |vauthors=Bruce DA, Alavi A, Bilaniuk L, Dolinskas C, Obrist W, Uzzell B |title=Diffuse cerebral swelling following head injuries in children: the syndrome of "malignant brain edema" |journal=J. Neurosurg. |volume=54 |issue=2 |pages=170–8 |date=February 1981 |pmid=7452330 |doi=10.3171/jns.1981.54.2.0170 |url=}}</ref>
==pathophysiology==
*Intracranial pressure is normally ≤15 mmHg in adults, and pathologic intracranial hypertension (ICH) is present at pressures ≥20 mmHg.
 
*ICP is normally lower in children than adults.
Hydrocephalus is usually due to blockage of [[cerebral spinal fluid]] ([[CSF]]) outflow in the brain ventricles or in the[[subarachnoid space]] over the brain. In a normal healthy person, [[CSF]] continuously circulates through the brain and its ventricles and the [[spinal cord]] and is continuously drained away into the circulatory system. In a hydrocephalic situation, the fluid accumulates in the ventricles, and the [[skull]] may become enlarged because of the great volume of fluid pressing against the brain and skull. Alternatively, the condition may result from an overproduction of the CSF fluid, from a congenital malformation blocking normal drainage of the fluid, or from complications of [[head injuries]] or infections.<ref>[http://www.ninds.nih.gov/disorders/hydrocephalus/detail_hydrocephalus.htm "Hydrocephalus Fact Sheet"], National Institute of Neurological Disorders and Stroke. (August 2005).</ref>
*In adults, the intracranial compartment is protected by the skull which can hold internal volume of 1400 to 1700 mL.
 
*Mass lesions, abscesses, and hematomas also causes the intracranial compartment pressure.
Infants and young children with hydrocephalus typically have abnormally large heads, because the pressure of the fluid causes the individual skull bones — which have not knitted with each other yet — to bulge outward at their juncture points. Compression of the brain by the accumulating fluid eventually may cause [[convulsions]] and [[mental retardation]]. Hydrocephalus occurs in about one out of every 500 live births<ref name="vle">[http://domino.lancs.ac.uk/info/lunews.nsf/I/DF8AAD55E15FABAB802570CA003E43B0 Eat your way to a better brain for your baby] December 2005. Virtual Learning Environment (VLE)</ref> and was routinely fatal until surgical techniques for shunting the excess fluid out of the [[central nervous system]] and into the blood or abdomen were developed.  
*ICP is a function of the volume and compliance of each component of the intracranial compartment.
 
*The volume of brain parenchyma is relatively constant in adults which constitutes 80% of total volume.
The [[elevated intracranial pressure]] may cause compression of the brain, leading to brain damage and other complications. Conditions among affected individual vary widely.  Children who have had hydrocephalus may have very small ventricles.
*The volumes of CSF and blood in the intracranial space vary to a greater degree.
 
*Abnormal increases in the volume due to mass lession or cerebral edema which lead to ICP elevation.
If the foramina (''pl.'') of the [[fourth ventricle]] or the [[cerebral aqueduct]] are blocked, cereobrospinal fluid (CSF) can accumulate within the ventricles. This condition is called '''internal hydrocephalus''' and it results 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 compresses the [[nervous tissue]] and dilates the ventricles. 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]].
*The volume of brain parenchyma is constant, with the exception of any abnormality like mass lesions or cerebral edema.
 
*The volumes of CSF and blood in the intracranial space vary to a greater degree.
Usually, hydrocephalus need not cause any [[intellectual impairment]] if recognized and properly treated. A massive degree of hydrocephalus rarely exists in normally functioning people, and such rarity may occur if onset is gradual rather than sudden.<ref>[http://www.newscientist.com/article.ns?id=dn12301&amp;feedId=online-news_rss20 "Man with tiny brain shocks doctors"], ''New Scientist'' ([[2007-07-20]]).</ref>
*CSF is produced by the choroid plexus and elsewhere in the central nervous system (CNS) at a rate of approximately 20 mL/h (500 mL/day).
 
*CSF is resorbed by arachnoid granulations into the venous system.  
 
*CSF abnormal flow generally result from impaired outflow due to ventricular obstruction or venous congestion.
*The Venous sinus thrombosis can be pathologically increase which can be seen in the setting of choroid plexus papilloma.
*The other causes of increased ICP are given below:
**Intracranial mass lesions (eg, tumor, hematoma).
**Cerebral edema.
**[[Acute hypoxic ischemic encephalopathy]].
**Large [[cerebral infarction]].
**Severe traumatic [[brain injury]].
**Choroid plexus papilloma (increased ICP).
**Arachnoid granulation adhesions after bacterial meningitis (decreased ICP).
**Venous sinus thrombosis.
**Idiopathic intracranial hypertension (pseudotumor cerebri).


== References ==
== References ==
{{reflist|2}}
{{reflist|2}}


[[Category:Grammar]]
[[Category:Neurological disorders]]
[[Category:Disease]]
[[Category:Neurology]]
[[Category:Pediatrics]]
 
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Latest revision as of 02:46, 23 August 2018

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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 mostly results due to CSF flow obstruction, hindering the free passage of cerebrospinal fluid through the ventricular system and it can also be caused by overproduction of cerebrospinal fluid (relative obstruction).

Pathophysiology

  • The pathophysiology of hydrocephalus is given below:.[1][2][3][4][5]
  • Intracranial pressure is normally ≤15 mmHg in adults, and pathologic intracranial hypertension (ICH) is present at pressures ≥20 mmHg.
  • ICP is normally lower in children than adults.
  • In adults, the intracranial compartment is protected by the skull which can hold internal volume of 1400 to 1700 mL.
  • Mass lesions, abscesses, and hematomas also causes the intracranial compartment pressure.
  • ICP is a function of the volume and compliance of each component of the intracranial compartment.
  • The volume of brain parenchyma is relatively constant in adults which constitutes 80% of total volume.
  • The volumes of CSF and blood in the intracranial space vary to a greater degree.
  • Abnormal increases in the volume due to mass lession or cerebral edema which lead to ICP elevation.
  • The volume of brain parenchyma is constant, with the exception of any abnormality like mass lesions or cerebral edema.
  • The volumes of CSF and blood in the intracranial space vary to a greater degree.
  • CSF is produced by the choroid plexus and elsewhere in the central nervous system (CNS) at a rate of approximately 20 mL/h (500 mL/day).
  • CSF is resorbed by arachnoid granulations into the venous system.
  • CSF abnormal flow generally result from impaired outflow due to ventricular obstruction or venous congestion.
  • The Venous sinus thrombosis can be pathologically increase which can be seen in the setting of choroid plexus papilloma.
  • The other causes of increased ICP are given below:
    • Intracranial mass lesions (eg, tumor, hematoma).
    • Cerebral edema.
    • Acute hypoxic ischemic encephalopathy.
    • Large cerebral infarction.
    • Severe traumatic brain injury.
    • Choroid plexus papilloma (increased ICP).
    • Arachnoid granulation adhesions after bacterial meningitis (decreased ICP).
    • Venous sinus thrombosis.
    • Idiopathic intracranial hypertension (pseudotumor cerebri).

References

  1. ↑ "Hydrocephalus Fact Sheet", National Institute of Neurological Disorders and Stroke. (August 2005).
  2. ↑ Strandgaard S, Paulson OB (June 1989). "Cerebral blood flow and its pathophysiology in hypertension". Am. J. Hypertens. 2 (6 Pt 1): 486–92. PMID 2757806.
  3. ↑ Strandgaard S, Andersen GS, Ahlgreen P, Nielsen PE (1984). "Visual disturbances and occipital brain infarct following acute, transient hypotension in hypertensive patients". Acta Med Scand. 216 (4): 417–22. PMID 6516910.
  4. ↑ Enevoldsen EM, Jensen FT (May 1978). "Autoregulation and CO2 responses of cerebral blood flow in patients with acute severe head injury". J. Neurosurg. 48 (5): 689–703. doi:10.3171/jns.1978.48.5.0689. PMID 641549.
  5. ↑ Bruce DA, Alavi A, Bilaniuk L, Dolinskas C, Obrist W, Uzzell B (February 1981). "Diffuse cerebral swelling following head injuries in children: the syndrome of "malignant brain edema"". J. Neurosurg. 54 (2): 170–8. doi:10.3171/jns.1981.54.2.0170. PMID 7452330.


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