Brain Abscess Flashcards
what is a brain abscess
Brain abscess is a suppurative collection of microbes (most often bacterial, fungal, or parasitic) within a gliotic capsule occurring within the brain parenchyma. Lesions may be single or multi-focal.
aetiology/ causes of a brain abscess
bacterial, fungal or parasitic causes
in what part of the brain do brain abscesses occur
ischaemic white matter adjacent to the cortex
why do brain abscesses usually occur in the ischaemic white matter
increased vascular density in the white matter can promote collagen deposition and capsule formation
cerebritis stages
Early cerebritis: lasts approximately 3 days and is characterised by local inflammation, tissue necrosis, neutrophilic infiltrate, and activation of microglia and astrocytes.
Late cerebritis: occurs on days 4 to 9 and is represented by increased organisation where lymphocytic and microglial infiltration is seen.
Frank abscess formation: present after day 10 and is characterised by encapsulation and a suppurative collection.
method of spread to lead to multi-focal abscesses
direct extension (via adjacent cells) or via haematogenous spread (via the bloodstream)
permeability of BBB in a brain abscess
increased permeability can be seen on a CT etc
benefits of an increased permeability of BBB
better penetration of antibiotics
presentation of a brain abscess
meningusmus, headache, Kernig or Brudzinkis sign, cranial nerve palsy, fever (inflammatory process- calor),
brain abscess in infants presentation
increased head circumference and bulging fontanelles
some risk factors for brain abscess formation
sinusitis, meningitis, otitis media, endocarditis, congenital cardiac failure, diabetes mellitus, HIV
epidemiology
males are affected more, age over 30 is a risk factor
first line investigations
bloods; FBC, ESR, CRP, PT and APTT, blood cultures
investigations imaging
MRI, CT and ultrasound
on what basis do you treat a brain abscess
depending on what caused it
