Space Occupying Lesions of the CNS (Week 2--Yong) Flashcards Preview

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Flashcards in Space Occupying Lesions of the CNS (Week 2--Yong) Deck (18)

Some pathologies of mass lesions/mass effect

Solid masses

Cystic lesions


Infarct (acute/subacute)



Cerebral edema


Brain herniation

Brain moves into place it's not supposed to be

Major consequence of mass effect


Arteries supplying the brain

ACA to top/center

MCA to middle/lateral

PCA to bottom


What can infarct cause a few days later?


Edema greatest at 4 days after infarct


Hemorrhages and their causes

Deep gray matter hemorrhage caused by hypertension

Superficial lobar hemorrhage in older person seen with cerebral amyloid angiopathy caused by Alzheimer disease (A-beta depositions)

Multiple hemorrhages caused by coagulopathy, fungal abscesses, certain metastatic tumors

Complex vasculature hemorrhage caused by vascular malformations



Extra-axial mass pushing on brain

If slow-growing, brain will give way and accommodate



AKA meningitis

Infectious and chemical

Acute purulent/PMN meningitis is bacterial

Acute lymphocytic meningitis is viral

Chronic meningitis due to various agents

Get fever, headache, stiff neck, altered mental status


Chronic meningitis

Bacteria and fungi

M Tuberculosis--lymphoplasmacytic and histiocytic, sometimes granulomatous (TB)

Cryptococcus neoformans--may elicit minimal inflammation

Can cause endarteritis obliterans followed by infarcts

Same as acute meningitis but sometimes no signs


Solid masses



Tumefactive multiple sclerosis

Metastases and GBMs are usually solid or ring enhancing, can have necrotic center

Solitary in brain is often glioma (GBM)

Multiple lesions more often metastases and abscesses (hemorrhages too)


Glioblastoma (GBM)

Thick irregular wall of enhancement with gadolinium on MRI



Smooth circumferential wall on MRI


Tumefactive multiple sclerosis

Smooth crescent of enhancement


Butterfly glioma (GBM)

Tumor that spans both hemispheres (crosses corpus callosum and is bilateral)


Brain cysts

Arachnoid cyst on surface of brain

Rathke cleft cyst, craniopharyngioma on pituitary/suprasellar

Pineal cyst

Choroid plexus cyst

Colloid cyst of 3rd ventricle

Cysticerosis, hydatid cyst in brain

Cyst with mural nodule in brain (temporal lobe, cerebellum, pliocytic astrocytoma, ganglioglioma, hemangioblastoma)

Mass with cystic change--metastasis, GBM



Excess CSF in the brain

Noncommunicating (obstructive): obstruction of CSF flow in ventricles (tumor, infection); colloid cyst at top of 3rd ventricle gets large lateral ventricles; aqueductal stenosis gets large 3rd and lateral ventricles

Communicating (non-obstructive): no obvious blockage between ventricles and arachnoid; obstruction at leptomeninges or arachnoid granulations (post hemorrhage, meningitis); hydrocephalus ex vacuo (compensatory dilatation of ventricles from cerebral atrophy--Alzheimers)


Cerebral edema

Cerebral edema secondary to mass lesion (tumor) can amplify mass effect; metastases typically have disproportionate edema

Vasogenic edema: normal BBB disrupted, fluid in extracellular spaces (around tumor and abscesses), white matter

Cytotoxic edema: injury to cells and cells swell because of substrate and energy failure; fluid in intracellular spaces (ischemia); grey and white matter

Many lesions have combinations of above edema types

Edema commonly leads to brain herniation


Brain herniation

Uncal = transtentorial, lateral transtentorial: medial temporal lobe (uncus) compresses against tentorium cerebelli; CN III and PCA compressed

Central = diencephalic, central tentorial: downward displacement of diencephalon, may have bilateral uncal herniation

Subfalcine: cingulate gyrus under falx; ACA compressed

External = transcalvarial: brain tissue thru dural/skull defect

Tonsillar: cerebellar tonsils thru foramen magnum; brain stem/respiratory centers compressed

Duret hemorrhages: brainstem herniation causes hemorrhages; often linear and midline, secondary to tearing of blood vessles


Take home points

Butterfly glioma = GBM

Ring enhancing = GBM, metastasis, abscess

Cyst with mural nodule = pliocytic astrocytoma, ganglioma, hemangioblastoma

Pituitary cyst = Rathke cleft cyst

Multiple cysts = cysticercosis

Multiple masses = metastases, fungi/bacteria

Hemorrhagic lesions = coagulopathic, fungi, melanoma, renal cell carcinoma, choriocarcinoma

Superficial lobar hemorrhage = cerebral amyloid angiopathy (Alzheimer's)

Deep/basal ganglia hemorrhage = hypertension

Cortical ribbon lesion = infarct; 4 day old infarct has edema/mass effect; old (months to years) there is loss of tissue

Sulcal/leptomeningeal lesion = meningitis, carcinomatosis

Hydrocephalus = communicating vs non-communicating

Edema = vasogenic vs cytotoxic

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