CNS Infection Flashcards
intracranial bacterial infections
pyogenic abscess, tuberculoma, lyme disease
pyogenic abscess cause, appearance
cause: hematogenous dissemination, direct spread from paranasal sinuses/mastoids, complication of bacterial meningitis
appearance: T2 hypointense rim, restricted diffusion
stages of pyogenic infection
early cerebritis, late cerebritis, early abscess, late abscess; 2 weeks to develop
nonspecific T2 prolongation with eventual rim enhancing mass with thin/smooth rim
tuberculoma
localized TB granuloma; central hypointensity
similar to pyogenic abscess
lyme disease
spirochete Borrelia burgdorferi; T2 prolongation within the frontal subcortical white matter
enhancement of CN or meninges too
cryptococcus
cryptococcus neoformans; fungal infection
most common CNS fungal infections in AIDS (CD4 < 100)
chronic basilar meningitis; hydrocephalus
spreads via basal ganglia perivascular spaces leaving behind gelatinous peudocysts; produce cryptococcomas within the ventricles via choroid plexus
treat with fluconazole/amp B
most common CNS infectsions in AIDS
HIV encephalopathy, toxoplasmosis, cryptococcus
parasitic CNS infections
neurocysticercosis, toxoplasmosis
neurocysticercosis
Taenia solium tapeworm; common in immunocompetent patients; presents with seizures
stages of neurocysticercosis
1) viable/vesciular: CSF intensity cysts, no enhancements; central dot (scolex)
2) colloidal: ring enhancing lesions; increased diffusivity
3) nodular/granlar: edema as cyst involutes, cyst wall thickens
4) calcified: parenchymal calcifications with small foci of susceptibility (GRE)
racemose neurocystericercosis
variant without scolex
intraventricular neurocysticercosis
typically aqueduct of Slyvius or 4th ventricle; obstructing cyst only visible on FLAIR
toxoplasmosis
most common mass lesion in AIDS; CD4 < 100
parasite toxoplasma gondii
multiple ring enhancing lesions, typically basal ganglia with nodular enhancement
ddx for toxoplasmosis
CNS lymphoma
toxo does not restrict diffusion and does not demonstrate increased CBV
toxo is hypometabolic on FDG PET and not avid on thallium
viral CNS infections
herpes encephalitis, HIV encephalopathy, CMV encephalitis
herpes encephalitis
HSV1; reactivation from trigeminal ganglion
fever, mesial temporal lobe signal abnormality, altered mental status
may have edema, hemorrhage, necrosis
PCR of HSV in CSF, lumbar puncture
ddx for medial temporal lobe lesions
herpes encephalitis, MCA infarct, infiltrating glioma, limbic encephalitis, seizure-related changes
HIV encephalopathy
most common CNS infection in AIDS; progressive neurodegenerative disease
diffuse cerebral atrophy and T2 prolongation in periventricular and deep white matter; spares subcortical U fibers
CMV encephalitis
disease of immunosuppressed; CD4 < 50
ventriculitis or meningoencephalitis
subependymal FLAIR hyperintensity and enhancement throughout ventricular system
common TORCH infection in neonates»_space; atrophy, encephalomalacia, ventricular enlargement, periventricular calcification
creudtzfeldt jakob disease
neurodegenerative disease caused by prion
cortical ribonning with FLAIR hyperintensity and restricted diffusion of cortex; may also affect basal ganglia and thalami; motor cortex spared
pulvinar sign
hockey stick sign
pulvinar: DWI and FLAIR signals in pulvinar nucleus of thalami
hockey stick: DWI/FLAIR signal in dorsomedial thalamus
toxic/metabolic white matter changes
liver disease, hypoglycemia, hypoxic ischemic encephalopathy, methanol poisoning, carbon monoxide
liver disease brain findings
hyperintense T1 signal in the globus pallidus/substantia nigra (manganese deposition?)
hypoglycemia brain findings
bilateral T2 prolongation in gray matter (cortex, hippocampi, basal ganglia)
hypoxic ischemic encephalopathy
circulatory/respiratory failure»_space; global hypoxia/anoxia
gray matter (cerebral cortex/hppocampi, basal ganlia); worse prognosis if basal ganglia involved
white cerebellum sign (cerebellum hyperattenuating compared to supratentorial brain)
methanol poisoning
optic neuritis; hemorrhagic necrosis of putamen/white matter edema
carbon monoxid
T2 prolongation and restricted diffusion of globus pallidus
