Pediatric Meningitis / Cerebritis / Intracranial Abscess

  • Etiology: organisms responsible
    — Neonates – Group B Streptococcus (most common), Escherichia coli, Enterobacter, Citrobacter
    — Infants – Streptococcus pneumoniae (most common), Neiseria meningitidis, Haemophilus influenzae
    — Children – Neiseria meningitidis
  • MRI:
    — Meningitis – lack of sulcal suppression / CSF non suppressed on FLAIR and thickened enhancing meninges
    — Abscess – T2 hypointensity – think / smooth enhancing ring due to hemorrhage + paramagnetic free radicals in macrophages / enhancing ring / restricted diffusion = pus
  • Complications: communicating hydrocephalus due to obstruction at arachnoid villi -> transependymal flow
  • Clinical: subdural effusion during treatment of meningitis does not necessarily mean treatment failure

Radiology Cases of Meningitis / Cerebritis / Abscess

MRI of intracranial abscess due to sinusitis
Axial T2 MRI of the brain (above left) shows a mass in the right front lobe with surrounding vasogenic edema. Axial (above right) and coronal (below right) T1 MRI with contrast shows the mass to have thin rim enhancement and the coronal image also shows left maxillary sinusitis. The mass is shown to demonstrate diffusion restriction on diffusion-weighted imaging (below left).
CT of coalescent mastoiditis with intracranial abscess
Axial CT with contrast of the brain with bone windows (left) shows opacification and destruction of the right mastoid air cells while axial CT with contrast of the brain with soft tissue windows (right) shows a large low density ring enhancing lesion in the right cerebral hemisphere that is causing midline shift to the left.