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KEY FACTS Terminology Intracranial atherosclerotic vascular disease (ASVD) Intracranial atherosclerotic stenosis (ICAS) Imaging Gold standard is now high-resolution MR (HRMR) with direct vessel wall imaging HRMR vessel wall imaging > > depicting lumen (DSA, CTA, MRA) Imaging findings (HRMR) Crescent-shaped or eccentric thickening May show asymmetric hyperintensity of intraplaque hemorrhage on T1WI Noncircumferential, short segment, irregular enhancement CTA/MRA/DSA Visualizes lumen, not wall Warfarin-aspirin symptomatic intracranial disease…

KEY FACTS Terminology Sclerosis of small-sized arteries (arterioles) Common with chronic hypertension (HTN) &/or diabetes May lead to vascular dementia (VaD) Imaging Multifocal white matter (WM) hypodensity on CT Patchy/confluent ↑ T2/FLAIR hyperintensities Broad or confluent base with ventricles Periventricular > deep > juxtacortical involvement Findings nonspecific Large number of causes other than arteriopathy Demyelination, infection, inflammatory, drug related, metabolic, age related Caused by several types…

KEY FACTS Terminology Hypertensive intracranial hemorrhage (hICH) Acute nontraumatic intracerebral hemorrhage (ICH) secondary to systemic hypertension 2nd most common cause of stroke Imaging Initial screen = NECT in patients with HTN CT: Acute round or oval hyperdense mass Striatocapsular: Putamen/external capsule (60-65%) Thalamus (15-25%) Pons, cerebellum (10%) Multifocal “microbleeds” (1-5%) Heterogeneous density (coagulopathy, active bleed) Other findings: Intraventricular extension, mass effect, hydrocephalus, herniation MR signal intensity…

KEY FACTS Terminology Primary intraparenchymal hemorrhage (pICH) Acute nontraumatic intracranial hemorrhage (ICH) Imaging Acute round or oval intracerebral hematoma Subcentimeter “microbleeds” to massive ICH Hematoma location for common causes of pICH HTN: Basal ganglia > thalamus > pons > cerebellum Amyloid angiopathy: Lobar Arteriovenous malformation: Any location Cavernous malformation: Any location Venous sinus thrombosis: Subcortical white matter Neoplasm: Any location Recommended imaging: Begin with NECT If…

KEY FACTS Imaging CT: Hemorrhage appearance based on density Hyperdense mass (50-70 Hounsfield units) on NECT Peripheral edema develops over 1st few days MR: Intracranial hemorrhage staging based on T1 and T2 signal characteristics MR as sensitive as CT in hyperacute phase; more sensitive in subacute/chronic phases Hematoma matures more slowly in center (core) than in periphery – Therefore MR signal change proceeds peripherally to centrally…

Introduction Stroke is a generic term that describes the clinical event of a sudden onset of neurologic deficit secondary to cerebrovascular disease. Stroke has 4 main etiologies, including cerebral infarction (80%), intraparenchymal hemorrhage (15%), nontraumatic subarachnoid hemorrhage (5%), and venous infarction (~ 1%). Clinically, ischemic infarction is the most common etiology and will be the main topic of this introduction. The principal cause of cerebral infarction…

TERMINOLOGY Abbreviations Superior sagittal sinus (SSS) Inferior sagittal sinus (ISS) Internal cerebral vein (ICV) Straight sinus (SS) Great cerebral vein (vein of Galen, VofG) Transverse sinus (TS) Superior/inferior petrosal sinuses (SPS/IPS) Cavernous sinus (CS) Internal jugular vein (IJV) Basal vein of Rosenthal (BVR) Superficial, deep middle cerebral veins (SMCV; DMCV) Definitions Dural sinuses are large, endothelial-lined trabeculated venous channels encased within folds/reflections of dura that define,…

TERMINOLOGY Abbreviations Anterior, middle, posterior cerebral arteries (ACA, MCA, PCA) Anterior, posterior communicating arteries (ACoA, PCoA) Basilar artery (BA) Vertebral artery (VA) Anterior, posterior inferior cerebellar arteries (AICA, PICA) Anterior choroidal artery (AChoA) Recurrent artery of Heubner (RAH) GROSS ANATOMY You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

KEY FACTS Terminology Definition Neurodegenerative disease secondary to repetitive concussive/subconcussive head injuries Synonyms Dementia pugilistica (“punch-drunk”) Postconcussion syndrome Imaging MR Age-inappropriate volume loss – Voxel-based morphometry shows disproportionate involvement of medial temporal lobes Nonspecific T2/FLAIR punctate, confluent hyperintensities in deep, periventricular white matter (WM) DTI shows loss of WM integrity – Uncinate and superior/inferior longitudinal fasciculi T2* shows microbleeds in ~ 10% PET Temporoparietal hypometabolism on…

KEY FACTS Terminology Direct carotid cavernous fistula (CCF), high-flow CCF Single-hole tear/transection of cavernous internal carotid artery (ICA) with arteriovenous shunt into cavernous sinus (CS) Imaging General features Proptosis, dilated superior ophthalmic vein (SOV) and CS, extraocular muscle enlargement Skull base fracture involving sphenoid bone/carotid canal ↑ likelihood of ICA injury MRA: ↑ flow-related signal in CS and SOV CT/CTA may be suggestive; should proceed to…

KEY FACTS Terminology Dissection Intramural hematoma extends along vessel wall Dissecting aneurysm Dissection + aneurysmal dilation contained by adventitia Pseudoaneurysm Lumen contained by thrombus outside vessel wall Imaging Location Often adjacent to falx, skull, tentorium, or region of significant motion Posterior circulation most common – Vertebral arteries most common site (72%) – Extension into basilar artery rare Anterior circulation uncommon – Supraclinoid internal carotid artery –…

KEY FACTS Terminology Dysautoregulation/second impact syndrome Repeated head trauma within “window of vulnerability” before brain recovers from initial concussive injury May cause catastrophic brain swelling Imaging Thin, acute subdural hematoma (aSDH) Disproportionate mass effect – Midline (subfalcine) shift more than accounted for by thickness of aSDH Swollen, hypodense cerebral hemisphere under aSDH Underlying sulci compressed, then obliterated Best imaging tools NECT (initial screening) ± MR with…

KEY FACTS Terminology Brain death (BD); death by neurological criteria (DNC) Complete, irreversible cessation of brain function Imaging No flow in intracranial arteries or venous sinuses No intravascular enhancement on CT or MR Light-bulb sign on radionuclide study Diffuse cerebral edema Gyri swollen, ventricles/cisterns compressed Gray-white matter borders effaced EEG plus bedside scintigraphy (Neurolite) Evoked potentials enable neurofunctional evaluation of comatose patient Top Differential Diagnoses Reversible…

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KEY FACTS Terminology Brain displaced from 1 compartment into another Imaging Subfalcine herniation Cingulate gyrus displaced under falx Lateral ventricle compressed/displaced across midline Contralateral ventricle dilated Unilateral descending transtentorial herniation (DTH) Temporal lobe displaced medially into incisura Encroaches on, then effaces suprasellar cistern Bilateral DTH (“central herniation”) Both temporal lobes herniated into tentorial hiatus Diencephalon crushed against skull base Suprasellar cistern, cerebrospinal fluid spaces obliterated Midbrain/pons…

KEY FACTS Terminology Subcortical injury (SCI): Deep diffuse axonal injury lesions of brainstem, basal ganglia, thalamus, and regions around 3rd ventricle Intraventricular hemorrhage (IVH): Hemorrhage within ventricular system Choroid hemorrhage (CH): Hemorrhage localized to choroidal plexus Imaging SCI: FLAIR most sensitive → hyperintense foci IVH: Hyperdense intraventricular blood; fluid-heme level common CH: Localized hyperdense choroidal hemorrhage Top Differential Diagnoses SCI: Cavernous malformation, lacunar infarcts, small-vessel ischemia…

KEY FACTS Terminology Traumatic axonal stretch injury Imaging General features Can be hemorrhagic or nonhemorrhagic – Microbleeds important imaging marker for diffuse axonal injury (DAI) – Intraventricular hemorrhage correlates with DAI Location – Subcortical/deep white matter (WM), corpus callosum – Deeper brain involvement = ↑ severity, poor prognosis NECT often normal (50-80%) MR FLAIR: Hyperintense foci T2* GRE: Hypointense “blooming” foci (hemorrhage) SWI: Depicts significantly more…

KEY FACTS Terminology Brain surface injuries involving gray matter and contiguous subcortical white matter Imaging Best diagnostic clue: Patchy hemorrhages within edematous background Characteristic locations: Adjacent to irregular bony protuberance or dural fold Anterior inferior frontal lobes and anterior inferior temporal lobes most common FLAIR: Best for hyperintense cortical edema and subarachnoid hemorrhage GRE: Hypointense hemorrhagic foci “bloom” Best imaging tool CT to detect acute hemorrhagic…

KEY FACTS Terminology Blood within subarachnoid spaces Contained between pia and arachnoid membranes Imaging High density on CT, hyperintensity on FLAIR Top Differential Diagnoses Nontraumatic SAH Meningitis: Cellular and proteinaceous debris Carcinomatosis meningitis Pseudosubarachnoid hemorrhage Gadolinium administration High inspired oxygen Pathology Associated with contusions, subdural or epidural hematoma, diffuse axonal injury Clinical Issues Headache, emesis, decreased consciousness Trauma is most common cause of subarachnoid hemorrhage (SAH)…