Brain abscess pathophysiology: Difference between revisions
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__NOTOC__ | __NOTOC__ | ||
{{CMG}} | {{CMG}}; {{AE}} {{FH}} | ||
{{Brain abscess}} | {{Brain abscess}} | ||
==Overview== | ==Overview== | ||
Brain abscesses are usually polymicrobial in nature. Swelling and irritation (inflammation) develop in response to this infection. Infected brain cells, white blood cells, live and dead bacteria, and fungi collect in an area of the brain. Tissue forms around this area and creates a mass. While this immune response can protect the brain by isolating the infection, it can also do more harm than good | Brain abscesses are usually polymicrobial in nature. Swelling and irritation ([[inflammation]]) develop in response to this infection. Infected brain cells, [[white blood cells]], live and dead bacteria, and [[fungi]] collect in an area of the brain. Tissue forms around this area and creates a mass. While this immune response can protect the brain by isolating the infection, it can also do more harm than good. Infected material can block the blood vessels of the brain. Although underlying pathology ([[tumor]], [[blood]] etc.) can sometimes be a nidus for infection, the majority of cases occur in a previously healthy brain. | ||
== Pathophysiology == | == Pathophysiology == | ||
===Pathogenesis=== | ===Pathogenesis=== | ||
The location of the primary lesion may be suggested by the location of the abscess. It depends on the source of infection, as does the specific microbial flora. Roughly 25% result from hematogenous seeding from extra-cranial infection. Penetrating trauma accounts for nearly 10% of cases. About 20 to 30% of cases are iodiopathic, and no obvious focus can be identified. | The location of the primary lesion may be suggested by the location of the abscess. It depends on the source of infection, as does the specific microbial flora. Roughly 25% of brain abscess result from hematogenous seeding from extra-cranial infection. Penetrating trauma accounts for nearly 10% of cases. About 20 to 30% of cases are iodiopathic, and no obvious focus can be identified. | ||
Common locations include: | Common locations include:<ref>{{cite book | author=Macewan W | year=1893 | title=Pyogenic Infective Diseases of the Brain and Spinal Cord | location=Glasgow | publisher=James Maclehose and Sons }}</ref><ref>{{cite book | author=Ingraham FD, Matson DD | title=Neurosurgery of Infancy andChildhood | location=Springfield, Ill | publisher=Charles C Thomas | year=1954 | pages=377 }}</ref><ref>{{cite journal | author=Raimondi AJ, Matsumoto S, Miller RA | title=Brain abscess in children with congenital heart disease | journal=J Neurosurg | volume=23 | pages=588–95 | year=1965 }}</ref> | ||
*Infections of the middle ear result in lesions in the [[middle cranial fossa|middle cranial fossal]] | *Infections of the middle ear result in lesions in the [[middle cranial fossa|middle cranial fossal]]. | ||
**Approximately 47% of cases arise from a contiguous infection, most commonly in the middle ear, the paranasal sinuses and teeth. | **Approximately 47% of cases arise from a contiguous infection, most commonly in the middle ear, the paranasal sinuses and teeth. | ||
*[[posterior cranial fossa|Posterior]] cranial fossae | *[[posterior cranial fossa|Posterior]] cranial fossae | ||
*[[Congenital heart disease]] with right-to-left shunts often result in abscesses in the distribution of the [[middle cerebral artery]] | *[[Congenital heart disease]] with right-to-left shunts often result in abscesses in the distribution of the [[middle cerebral artery]]. | ||
*Infection of the [[frontal sinus|Frontal]] and [[ethmoid sinus|Ethmoid]] sinuses usually results in collection in the subdural sinuses. | *Infection of the [[frontal sinus|Frontal]] and [[ethmoid sinus|Ethmoid]] sinuses usually results in collection in the subdural sinuses. | ||
The most common organism recovered from cultures is the [[bacterium]] ''[[Streptococcus]]''. A wide variety of other bacteria may cause brain abscess. These include: | The most common organism recovered from cultures is the [[bacterium]] ''[[Streptococcus]]''. A wide variety of other bacteria may cause brain abscess. These include:<ref name="urlBrain abscess - Wikipedia, the free encyclopedia">{{cite web |url=https://en.wikipedia.org/wiki/Brain_abscess#Pathophysiology |title=Brain abscess - Wikipedia, the free encyclopedia |format= |work= |Accessed on October 26, 2015=}}</ref> | ||
* | *[[Proteus (bacterium)|Proteus]]'', ''[[Pseudomonas]]'', ''[[Pneumococcus]]'', ''[[Meningococcus]]'', ''[[Haemophilus]] | ||
* [[fungus|Fungi]] | * [[fungus|Fungi]] | ||
**Fungi and parasites are especially associated with immunocompromised patients. | **Fungi and parasites are especially associated with immunocompromised patients. | ||
*Parasites | *Parasites | ||
* Organisms that are most frequently-associated with brain abscess in patients with [[AIDS]] are ''[[Mycobacterium tuberculosis]]'', ''[[Toxoplasma gondii]]'' and ''[[Cryptococcus neoformans]]'', though in infection with the latter organism, symptoms of [[meningitis]] generally predominate. | |||
* Bacterial abscesses rarely (if ever) arise ''de novo'' within the brain. There is almost always a primary lesion elsewhere in the body that must be sought assiduously, because failure to treat the primary lesion will result in relapse. In cases of trauma, for example in compound skull fractures where fragments of bone are pushed into the substance of the brain, the cause of the abscess is obvious. Similarly, bullets and other foreign bodies may become sources of infection if left in place.<ref name="urlBrain abscess - Wikipedia, the free encyclopedia">{{cite web |url=https://en.wikipedia.org/wiki/Brain_abscess#Pathophysiology |title=Brain abscess - Wikipedia, the free encyclopedia |format= |work= |accessdate=}}</ref> | |||
===Gross Pathology=== | ===Gross Pathology=== | ||
Experimental models have identified four stages for abscess formation. These include: | Experimental models have identified four stages for abscess formation. These include: | ||
:* Early cerebritis (days 1 – 3): focal inflammation and edema | :* Early cerebritis (days 1 – 3): focal inflammation and edema | ||
:* Late cerebritis ( | :* Late cerebritis (days 4 – 9): development of a necrotic center | ||
:* Early capsular ( | :* Early capsular (days 10 – 14): formation of a well-vascularized, ring-enhancing capsule with peripheral gliosis and/or fibrosis | ||
:* Late capsular: (after | :* Late capsular: (after 2 weeks): formation of a well-formed fibrous capsule | ||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} | ||
{{WS}} | |||
{{WH}} | |||
[[Category:Disease]] | [[Category:Disease]] | ||
[[Category:Up-To-Date]] | |||
[[Category:Neurology]] | [[Category:Neurology]] | ||
[[Category:Neurosurgery]] | |||
[[Category:Emergency medicine]] | |||
[[Category:Infectious disease]] | [[Category:Infectious disease]] | ||
Latest revision as of 20:41, 29 July 2020
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Farwa Haideri [2]
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Overview
Brain abscesses are usually polymicrobial in nature. Swelling and irritation (inflammation) develop in response to this infection. Infected brain cells, white blood cells, live and dead bacteria, and fungi collect in an area of the brain. Tissue forms around this area and creates a mass. While this immune response can protect the brain by isolating the infection, it can also do more harm than good. Infected material can block the blood vessels of the brain. Although underlying pathology (tumor, blood etc.) can sometimes be a nidus for infection, the majority of cases occur in a previously healthy brain.
Pathophysiology
Pathogenesis
The location of the primary lesion may be suggested by the location of the abscess. It depends on the source of infection, as does the specific microbial flora. Roughly 25% of brain abscess result from hematogenous seeding from extra-cranial infection. Penetrating trauma accounts for nearly 10% of cases. About 20 to 30% of cases are iodiopathic, and no obvious focus can be identified. Common locations include:[1][2][3]
- Infections of the middle ear result in lesions in the middle cranial fossal.
- Approximately 47% of cases arise from a contiguous infection, most commonly in the middle ear, the paranasal sinuses and teeth.
- Posterior cranial fossae
- Congenital heart disease with right-to-left shunts often result in abscesses in the distribution of the middle cerebral artery.
- Infection of the Frontal and Ethmoid sinuses usually results in collection in the subdural sinuses.
The most common organism recovered from cultures is the bacterium Streptococcus. A wide variety of other bacteria may cause brain abscess. These include:[4]
- Proteus, Pseudomonas, Pneumococcus, Meningococcus, Haemophilus
- Fungi
- Fungi and parasites are especially associated with immunocompromised patients.
- Parasites
- Organisms that are most frequently-associated with brain abscess in patients with AIDS are Mycobacterium tuberculosis, Toxoplasma gondii and Cryptococcus neoformans, though in infection with the latter organism, symptoms of meningitis generally predominate.
- Bacterial abscesses rarely (if ever) arise de novo within the brain. There is almost always a primary lesion elsewhere in the body that must be sought assiduously, because failure to treat the primary lesion will result in relapse. In cases of trauma, for example in compound skull fractures where fragments of bone are pushed into the substance of the brain, the cause of the abscess is obvious. Similarly, bullets and other foreign bodies may become sources of infection if left in place.[4]
Gross Pathology
Experimental models have identified four stages for abscess formation. These include:
- Early cerebritis (days 1 – 3): focal inflammation and edema
- Late cerebritis (days 4 – 9): development of a necrotic center
- Early capsular (days 10 – 14): formation of a well-vascularized, ring-enhancing capsule with peripheral gliosis and/or fibrosis
- Late capsular: (after 2 weeks): formation of a well-formed fibrous capsule
References
- ↑ Macewan W (1893). Pyogenic Infective Diseases of the Brain and Spinal Cord. Glasgow: James Maclehose and Sons.
- ↑ Ingraham FD, Matson DD (1954). Neurosurgery of Infancy andChildhood. Springfield, Ill: Charles C Thomas. p. 377.
- ↑ Raimondi AJ, Matsumoto S, Miller RA (1965). "Brain abscess in children with congenital heart disease". J Neurosurg. 23: 588&ndash, 95.
- ↑ 4.0 4.1 "Brain abscess - Wikipedia, the free encyclopedia".