Brain abscess: Difference between revisions

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**'''Congenital cardiac malformations''' (especially right-to-left shunts): [[Streptococcus species]]
 
**'''Congenital cardiac malformations''' (especially right-to-left shunts): [[Streptococcus species]]
 
*Direct inoculation (10%)
 
*Direct inoculation (10%)
** '''Penetrating head trauma:''' [[Staphylococcus aureus]], [[Enterobacter species]], [[Clostridium species]]
+
**'''Penetrating head trauma:''' [[Staphylococcus aureus]], [[Enterobacter species]], [[Clostridium species]]
 
**'''Neurosurgery:''' [[Staphylococcus species]], [[Streptococcus species]], [[Pseudomonas aeruginosa]], [[Enterobacter species]]
 
**'''Neurosurgery:''' [[Staphylococcus species]], [[Streptococcus species]], [[Pseudomonas aeruginosa]], [[Enterobacter species]]
 
*Cryptogenic (15%)
 
*Cryptogenic (15%)
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*Microbiology (above) depends on mechanism of infection
 
*Microbiology (above) depends on mechanism of infection
   
== Clinical Manifestations ==
+
==Clinical Manifestations==
   
* Often non-specific
+
*Often non-specific
* Headache is most common, then fever and focal neurological deficits
+
*Headache is most common, then fever and focal neurological deficits
* May have seizures
+
*May have seizures
* May have symptoms of increase ICP, such as comiting, blurry vision, drowiness, and confusion
+
*May have symptoms of increase ICP, such as comiting, blurry vision, drowiness, and confusion
   
=== Prognosis and Complications ===
+
===Prognosis and Complications===
   
* 10% mortality
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*10% mortality
* 50% seizures
+
*50% seizures
* 20% significant cognitive impairment
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*20% significant cognitive impairment
   
 
==Investigations==
 
==Investigations==
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*MRI with gadolinium
 
*MRI with gadolinium
 
**Typically demonstrates a ring-enhancing lesion with thin rim
 
**Typically demonstrates a ring-enhancing lesion with thin rim
**Temporal lobe or cerebellum suggests contiguous spread from chronic otitis or mastoiditis
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**Temporal lobe and cerebellum suggests contiguous spread from chronic otitis or mastoiditis
**Frontal lobe suggests contiguous spread from frontal or ethmoid sinusitis
+
**Frontal and temporal lobe suggests contiguous spread from frontal or ethmoid sinusitis
  +
**Frontal lobe and cerebellum can be secondary to meningitis
  +
**Frontal lobe scan be from dental infection or manipulation
 
**Multiple abscesses in a middle cerebral artery distribution suggests bacteremia
 
**Multiple abscesses in a middle cerebral artery distribution suggests bacteremia
 
*Blood cultures positive in 15%
 
*Blood cultures positive in 15%

Revision as of 07:55, 18 August 2020

Background

Microbiology

Pathophysiology

  • Either from contiguous spread from a head and neck infection, hematogenous spread from bacteremia or endocarditis, traumatic inoculation, or post-neurosurgery
  • Typically starts as a small focus of infection in the brain parenchyma, followed by cerebritis and eventual capsule formation to give an abscess
  • Microbiology (above) depends on mechanism of infection

Clinical Manifestations

  • Often non-specific
  • Headache is most common, then fever and focal neurological deficits
  • May have seizures
  • May have symptoms of increase ICP, such as comiting, blurry vision, drowiness, and confusion

Prognosis and Complications

  • 10% mortality
  • 50% seizures
  • 20% significant cognitive impairment

Investigations

  • MRI with gadolinium
    • Typically demonstrates a ring-enhancing lesion with thin rim
    • Temporal lobe and cerebellum suggests contiguous spread from chronic otitis or mastoiditis
    • Frontal and temporal lobe suggests contiguous spread from frontal or ethmoid sinusitis
    • Frontal lobe and cerebellum can be secondary to meningitis
    • Frontal lobe scan be from dental infection or manipulation
    • Multiple abscesses in a middle cerebral artery distribution suggests bacteremia
  • Blood cultures positive in 15%
  • Lumbar puncture usually contraindicated due to mass effect and risk of herniation
  • Most important is aspiration of abscess for stain and culture, which is positive in 2/3 of cases
    • Can do bacterial or fungal ribosomal PCR if cultures negative

Management

  • Empiric therapy is directed at the likely organisms based on etiology (direct vs. hematogenous spread)
  • Source control with neurosurgical aspiration
  • Duration is typically 6 to 8 weeks of intravenous antibiotics following source control
    • Monitor with serial MRI, though abnormalities may persist after successful treatment
  • No role for routine use of steroids

Further Reading