infections of CNS - brain abscess

Question 1

most common source of bacterial brain abscess

Answer 1

• pulmonary pathology, particularly bronchiectasis
• cyanotic congenital heart disease
• arteriovenous malformations

Question 2

why are congenital heart and vascular issues risk factors for brain abscess?

Answer 2

tend to shunt directly into left side of heart and miss filtration by pulmonary macrophage system

Question 3

typical quality of bacteria that cause brain abscess

Answer 3

anaerobic or microaerobic (from bowel)

Question 4

when are aerobic bacteria involved in brain abscess

Answer 4

• usually when directly connected to sinuses, middle ear, skull fractures

Question 5

most like locations for hematologically spread abscesses

Answer 5

• areas of ischemic injury

Question 6

locations of abscesses based on origin

Answer 6

ear infection - middle third of temporal lobe, cerebellum
sinuses and dental infections - frontal lobe
hematological - any location, often multiple

Question 7

describe first stage of brain abscess and treatment

Answer 7

• cerebritis
• febrile, still active primary infection
• inflammation, tissue breakdown
• raised intracranial pressure
• abnormalities on imaging but no defined mass on angiography
• antibiotics alone can often resolve it

Question 8

describe second stage of brain abscess and treatment

Answer 8

• cerebritis walls off and becomes true abscess
• afrebrile
• expanding mass
• surgical drainage may be needed

Question 9

complications of untreated brain abscess

Answer 9

• cerebral herniation

- rupture into ventricles causing severe meningitis (WBC count over 10,000/cu mm