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T2 Katz Neuro Test 2


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What cause lentiform nucleus obscuration and when can it be seen?
Cytotoxic edema in basal ganglia. It indicates proximal MCA occlusion-->so limited flow to lenticulostriate arteries.
-Seen as early as 1 hr post stroke onset.
What is the most consistent sign of infarction?
Diffuse hypodensity & sulcal effacement.
What does parenchymal hypodensity in greater than 50% of of MCA indicate?
85% mortality rate
Wht does hypodensity in greater than 1/3 of MCA indicate?
It a contraindication to thrombolytic therapy b/c of high incidence of hemorrhage.
What are the findings of a subacute infarction that 1-3 days old on CT?
-Increasing mass effect
-Wedge shaped low density
-Hemorrhagic transformation (dry to wet infarct)
What are the findings of a subacute infarction in 4-7 days on CT?
-Gyral enhancement
-Persistent mass effect
What are the findings of a subacute infarction on CT in 1-8 wks?
-Mass effect resolves
-Enhancement may persist.
What three factors cause enhancement in infarctions?
1. breakdown of BBB
2. neovascularity
3. reperfusion of damaged brain tissue
What are two types of extra-axial infections?
1. Meningitis
2. Subdural & Epidural infections
What are the three subtypes of meningitis?
1. Acute pyogenic meningitis-->usually bacterial
2. Lymphocytic meningitis-->usually viral, benign, & self-limited.
3. Chronic meningitis-->often in immunocompromised hosts, may be fungal or parasite.
Is imaging usually performed for meningitis?
-Its not performed to diagnose meningitis b/c imaging can turn out nl even w/ disease, but can be used in those suspected to assess safety of LP.
What types of conditions can lead to an abnormal increase of CSF in CNS?
cerebral atrophy & focal destructive lesions.
Which type of hydrocephalus is most common?
Communicating hydrocephalus, aka nonobstructive. Its caused by impaired CSF resorption in absence of any CSF-flow obstruction-->maybe dysfunctional arachnoid granules along superior sagittal sinus.
What are three causes of obstructive hydrocephalus?
aquuductal stenosis or occlusion, trapped 4th ventricle, ependymitis
50% of extra-axial infections are associated w/ what condition?
Sinusitis, usually frontal. Occurs by direct extension or septic thrombophlebitis.
What usually causes subdural empyemas?
meningitis, sinusitis, trauma, or prior surgery.
Which condition is an uncommon cause of cerebral infarction but its important b/c of its morbidity? Presents w/ HA & cranial nerve palsies
Venous thrombosis
What % of AIDS patients get neuro complications?
What are the most frequent causes of CNS complications in AIDS pts?
toxoplasmosis (10-33%)
primary CNS lymphoma (2-10%)
PML (10%)
What do CNS complications in AIDS pts appear like on CT?
hypodense masses w/ nodular or ring enhancement.
What 4 things will appear dark on T1 & T2?
calcifications, bone, air, slow flowing blood.
How do intracranial tumors present?
w/ focal neurological deficit, seizure, or HA.
Which intr-axial tumor is 50% of all primary CNS neoplasms?
Describe the grading system for astrocytomas.
-Grade I: benign or low grade
-->lack necrosis & endothelail proliferation

Grade II: same as above.
Grade III: anaplastic
-increased cellularity &
mitosis & pleomorphism
Grade IV: malignant --Glioblastoma --marked necrosis & endothelial proliferation.
What is the most aggressive grade of astrocytoma and what is its 2-yr survival rate?
Glioblastoma Multiforme, 10-15% survival.
Which lesion frequently crosses the corpus callosum?
Glioblastoma Multiforme.
What is the most common intracranial tumors in adults?
Metastasis: 35-50% of intracranial tumors.
What is the order of frequency of metastatic brain tumors (high to low)?
lung, breast, melanoma, renal, Colon CA.
How do CT & MRI correspond to one another in metastatic cancer to the brain?
Patient should do contrast enhanced CT & then followup by contrasted MRI.
-20% of pts who demonstrate a single lesion on CT may demonstrate multiple lesions on MRI.
Where do half of primary brain tumors in children originate?
posterior fossa;
What percent of pts w/ medulloblastoma have CSF dissemination at diagnosis?
What is the most common extra-axial neoplasm of the brain & who is most affected?
Meningiomas. Middle-aged women.
What are the advantages of CT scanning in imaging meningiomas?
-can see calcification of meningiomas.
-invasion of surrounding dura frequently provokes an osteoblastic reponse, causing hyperostosis.
-Can show acute tumor hemorrhage & widened vascular grooves in calvarium.
Are pituitary adenomas benign or malignant?
Almost always benign, w/ no malignant potential.
What is the most common demyelination disease & what is the usual age of onset?
MS, 3rd-4th decade.
What imaging technique should be used for MS?
What are typical locations for MS lesions?
periventricular white matter, brainstem, cerebellum, spinal cord.
What is the most common white matter lesion?
Ischemic demyelination, after age 60.

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