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79 Cards in this Set
- Front
- Back
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What are 6 types of CNS infections
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epidural abscess
subdural empyema meningitis pyogenic abscess ventriculitis encephalitis |
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What r 4 pathogens that effect the cns
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bacteria, viral, fungal, parasite
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What is the name of the two layers of the dura
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periosteal layer (outer)
meningeal layer |
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What are the leptomeniges
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the pia and arachnoid matter
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What are the 5 basic patterns/areas to CNS infection
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extra-axial
ring enhancing temporal lobe lesions basal ganglia lesions white matter lesions |
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What are areas of extra-axial infections
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epidural
subdural leptomeningeal |
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What is a key sequence when dealing with infection
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DWI
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What is a concern if a pt has severe sinusitis
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cavernous sinous thrombosis
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What is a sign of cavernous sinus thrombosis from sinusitis
5 |
opacified sinus
bowing out of the cavernous sinus non-enhancing cavernous sinus non-enhancing superior opthalamic vein (only if there is extension of thrombosis to this vein) rim of calcification of the middle cranial fossa with epidural collection (if there is an associated empyema) |
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Where do epidural empyemas (or abscess) come from
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sinuses
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How does a sinusitis commicate with the epidural space to form an empyema
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through bony erosions
valveless bridging veins |
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Are epidural empyemas lentiform or crescent shaped
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lentiform (like an epidural hematoma)
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What is the mc sinus to cause an empyema or abscess
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frontal
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What some complications that may result from epidural empyemas
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dural sinus thrombosis
osteomyelitis meningitis |
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How is a subdural effusion differentiated from a subdural empyema
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DWI (a subdural empyema is bright on DWI and dark on ADC)
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What is leptomeningitis
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Leptomeningitis (more commonly referred to as meningitis) refers to inflammation of the subarachnoid space (i.e. arachnoid mater and pia mater). It is usually infective.
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What are the MR findings of leptomeningitis (T1, T1 + gad, Flair)
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T1 : may be normal; sulci may appear less hypointense than normal
T1 C+ (GAD) : leptomeningeal enhancement FLAIR : demonstrates hyperintense signal in CSF space, especially in the sulci |
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What are some potential complications of leptomeningitis
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abscess
infarction hydrocephalus ventriculitis dural sinus thrombosis |
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What is a subdural effusion
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A subdural effusion (collection of pus beneath the dura) is a rare complication of bacterial meningitis (AKA leptomeningitis). Subdural effusion is more common in infants and in persons who have meningitis caused by Haemophilus influenzae.
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Does a subdural empyema have reduced diffusion
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yes (bright on DWI and dark on ADC) this will differentiate from subdural effusion
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What is the mortality rate of subdural empyema
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12-40%
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What is the treatment of a subdural empyema
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surgical evacuation
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What are complications associated with subdural empyema
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brain abscess, sinus thrombosis
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What is the leading cause of meningitis (leptomeningitis) in adults and young kids
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meningitis in kids
paranasal sinuses in adults |
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What percent of subdural empyemas are convexity and parafalcine
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50% convexity
20% parafalcine |
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What is the ddx for subdural empyema?
4 |
subdural empyema
subdural effusion chronic sdh hygroma |
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What is a subdural hygroma
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is a subdural collection of cerebrospinal fluid (CSF), without blood. Most subdural hygromas are believed to be derived from chronic subdural hematomas
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Does a subdural effusion cause cortical enhancement or bright signal on DWI
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no
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Are hygromas common in a history of trauma
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yes
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What is the ddx for bright signal of the subarachnoid space on flair
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tumor
meningitis SAH blood (slow flow ...ie ipsilateral carotid stenosis) following oxygen therapy |
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What is the meningoencephalitis
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is a medical condition that simultaneously resembles both meningitis, which is an infection or inflammation of the meninges, and encephalitis, which is an infection or inflammation of the brain.
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What are the complications of meningoencephalitis
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infarct
hydrocephalus subdural empyema dural sinus thrombosis |
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What is the cause of hyperdense material in the basal cistern
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90% blood
10% pus |
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What is the cause of pus in the basal cistern
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TB, fungal, sarcoid
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Where do the infarcts tend to occur during mengoencephalitis
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small basal ganglia infarcts because of adjacent inflammation
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Is CT sensitive for leptomeningitis
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no
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What is FLAIR and T1 + gad useful for when analyzing brain pathology
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subarchnoid abnormalities
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What is DWI useful for
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infarct or subdural empyema (complications)
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Where do acute bacterial and viral infections of the leptomengeal tend to affect
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The cerebrum (enhancement is seen)
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Where do chronic fungal or TB tend to affect
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the basilar cisterns
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What does the term 'pachymeningeal' refer to
What is the ddx of pachymeningeal enchancement 5 |
The dura mater, also known as the "pachymeninx," is called such because it is the thickest of the layers and pachymenigeal enhancement is basically enhancement of the dura
idiopathic hypertrophic cranial pachymeningitis intercranial hypotension dural mets infection sarcoidosis |
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Can sarcoidosis and intracranial hypotension cause pachymeningitis
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yes
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What does pachymeningitis look like
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thick enhancing covering of brain which follows the dural reflection
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What is the ddx of leptomeningeal enhancement
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meningitis
leptomeningeal tumor sarcoid |
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What is the ddx of ring enhancing lesion
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mets
pyogenic abscess GBM hematoma radiation necrosis tumefactive demylenation infarct atypical infection toxo lymphoma |
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What are the atypical infection which may cause ring enhancing lesion
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TB, neurocystocercosis, fungal, toxo
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What are 2 findings of the pyogenic abscess (one of the ring enhancing lesions)
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light bulb diffusion, thin enhancing
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Where do most mets tend to occur
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the G-W junction
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What are 3 components of GBM
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solid, necrotic and hemorrhagic component
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Where do GBMs tend to occur
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Corpus callosum
deep white matter |
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Where do metastasis to the brain normally occur
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grey-white junction
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What type of ring enhancing lesion is typically light bulb bright on DWI and has thin enhancement
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pyogenic abscess
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Where do GBMs typically occur
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the corpus callosum and the deep white matter
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Can a subacute hematoma have ring enhancement
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yes
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What MR sequence can help differentiate radiation necrosis (a type of ring enhancing lesion) from tumor recurrence
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MR perfusion
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Is the there incomplete ring of enhancement around tumefactive demyelination
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yes
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What are two characteristics that help differentiate tumefactive demyelination from other pathology
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incomplete ring of enhancement
little mass effect |
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What type of enhancement does an infarct tend to have
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gyriform enhancement (enhancement surrounding the gyri)
except in the cerebelum and basal ganglia where there may be an incomplete ring of enhancement |
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What is one cause of ring enhancement that are not in the MAGIC DR pneumonic
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lymphoma
under infection (TB, fungal, neurocytocercosis, toxo) |
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What is a reason why a patient may have multiple pyogenic abscess
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septic emboli
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What are the imaging characteristics of a pyogenic abscess on MR
(T1, T1+gad, T2, DWI) |
T1- hypointense
T1 + gad: ring enhancing lesion surrounding hypointense lesion T2: hyperintense with surrounding thin hypointense rim DWI: decreased diffusion (light bulb bright) |
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What are the complications of pyogenic abscess
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ventriculitis
subdural empyema dural sinus thrombosis |
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What are common causes of pyogenic abscess
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drug abuse
sepsis cardiac source pulmonary infection |
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What creates the rim of a pyogenic abscess
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asymmetric collagen deposition
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Where is the wall of an abscess typically the thinnest
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the side that is closest to the ventricle
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Do pyogenic abscess have a propensity for intraventricular rupture
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yes
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What type of cyst are often accompying a pyogenic abscess
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a daughter cyst
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What are two other ring enhancing lesion which may be bright on DWI
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lymphoma
high grade GBM |
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What are the MR characteristics of T2 for abscess
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hyperintense center with dark rim
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What are the 3 main causes of ventriculitis
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meningitis (leptomeningitis), intraventricular shunts, ruptured abscess
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Does ventriculitis typically occur without other pathology
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no
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What are the MR findings of ventriculitis
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subependymal enhancement
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What is the mortalitiy in a patient with subependymal enhancement
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80%
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What causes ring enhancing lesions of the brain in TB
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caseating tuberculoma
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A pt with fever, lethary, and abnormal cxr with a ring enhancing lesion
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TB
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What are the features of a caseating tuberuloma on non-contrast CT
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hyperdense on non-contrast
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What are the characteristics of a caseating tuberculoma on CT with contrast
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smooth ring enhancement
vasogenic edema |
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What are the characteristics of a caseating abscess on MR
(T1, T1 + gad, T2) |
T1: isointense to hyperintense
T1 + gad: isointense with ring of enhancement T2: homogeneously hypointense |
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What MR characteristics is most unique and indicates a ring enhancing lesion is most likely to be a caseating tuberculoma
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homogeneously hypointese on T2
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