Post-traumatic

Accidental or nonaccidental

Parenchymal hemorrhage: GM and contiguous subcortical WM

Typically adjacent to irregular bony protuberance or dural fold

Anterior inferior frontal and temporal lobes most common

± surrounding edema

± ST swelling, SDH, SAH, EDH, fracture

± mass effect and herniation

Contrecoup injury opposite impact site, frequently more severe than coup injury

Coronal reformats very helpful

Usually < 32 weeks; GA < 1,500 grams

Rare > 34 weeks gestational age

Rupture of germinal matrix capillaries due to alterations in CBF, ↑ in CVP, coagulopathy, capillary fragility, deficient vascular support, ↑ fibrinolysis

Hemorrhage in subependymal region, usually caudothalamic notch (grade 1)

± intraventricular hemorrhage (grade 2)

± ventriculomegaly (grade 3)

± cerebral hemorrhage (grade 4)

± cerebellar parenchymal hemorrhage

US: Initial imaging modality of choice

Secondary to trauma-induced axonal stretching

Usually high-velocity MVA

Hemorrhagic and nonhemorrhagic

CT: Frequently normal

MR: Punctate hemorrhages at GW junction > corpus callosum, deep GM, and brainstem

GRE/SWI for optimal imaging

± diffusion restriction

a.k.a. cavernomas

Benign collections of closely apposed vascular spaces (“caverns”)

May enlarge, regress, or form de novo

Sporadic > > familial (autosomal dominant with variable penetrance)

Hemorrhages of different ages

“Popcorn ball” appearance with mixed hyper/hypointense blood in locules

Hypointense hemosiderin rim on T2WI

± surrounding edema if acute

GRE/SWI for optimal imaging

Minimal or no CE of lesion

± adjacent enhancing DVA

Vascular malformation with AV shunting; no intervening capillary bed

Supratentorial > > > infratentorial

Usually solitary; multiple in HHT

Spetzler-Martin scale estimates surgical risk: Size (small, medium, large), location (noneloquent or eloquent area), and venous drainage (superficial or deep)

Enlarged arteries and draining veins

“Honeycomb” of flow voids

± calcification

± hemorrhage

± surrounding high signal gliosis

Posterior reversible encephalopathy syndrome (PRES)

Abnormal cerebrovascular autoregulation

Present with headache, seizure, and altered mental status

Associated with hypertension, uremic encephalopathies, drug toxicity, tumor lysis syndrome, and sepsis with shock

Multifocal edema in posterior parietal, occipital lobes > basal ganglia > brainstem

Frequently bilateral but asymmetric

Restricted diffusion uncommon

Hemorrhage in minority of lesions, may only be petechial hemorrhage on MR

Supratentorial and parenchymal hemorrhage most common

Mixed-density hemorrhages, ± fluid-fluid levels, unclotted blood, hemorrhage may be hypoechoic on US

Diligent search for hemorrhage in patients on ECMO

Reactivation in non-neonate, immunocompetent patient = HSV-1