Ischemia, Stroke & Hypoxic-Ischemic Insult

Neuroradiology Question Bank : Naveed Ahmad, MD

Case 1.1: Acute MCA Infarction & Cytotoxic Edema

• Scenario: A 68-year-old patient presents with acute-onset aphasia and right hemiplegia. Non-contrast head CT shows subtle effacement of the left insular ribbon. Diffusion-weighted imaging (DWI) reveals a bright, geographic restricted diffusion pattern in the left M1 through M6 cortical territories.
• Question: What biophysical shift produces restricted water diffusion on DWI during the hyperacute phase of cerebral ischemia?
• A) Extracellular vasogenic edema increasing free water mobility
• B) ATP depletion causing $\text{Na}^+/\text{K}^+$ pump failure, shifting water from the extracellular space into the intracellular compartment and restricting Brownian motion
• C) Active extravasation of gadolinium contrast through disrupted endothelial tight junctions
• D) Dystrophic micro-calcification within ischemic neurons
• Answer:B
• Explanation: Cellular energy failure leads to rapid cytotoxic edema, moving extracellular water into cells where mobility is restricted by macromolecules and cellular membranes.

Case 1.2: Global Hypoxic-Ischemic Encephalopathy (HIE)

• Scenario: Following cardiac arrest and resuscitation, a patient undergoes brain MRI. Findings include diffuse loss of gray-white matter differentiation and symmetric restricted diffusion within the basal ganglia, thalami, and cerebral cortex.
• Question: Which specific neuronal populations are exquisitely vulnerable to global hypoxic-ischemic injury due to high metabolic demand?
• A) Brainstem cranial nerve motor nuclei
• B) Hippocampal CA1 sector (Sommer sector), neocortical layers 3, 5, and 6, and cerebellar Purkinje cells
• C) Corpus callosum and internal capsule projection fibers
• D) Olfactory bulb glomeruli
• Answer:B
• Explanation: CA1 hippocampal neurons, cerebral cortical pyramidal neurons in layers 3, 5, and 6, and cerebellar Purkinje cells exhibit high metabolic rates and selective vulnerability to anoxia.

Case 1.3: Subacute Infarction & The “Fogging Effect”

• Scenario: A patient imaged 10 days after a middle cerebral artery stroke demonstrates an area of the brain that appears isoattenuating to surrounding parenchyma on non-contrast CT, obscuring the infarct boundaries.
• Question: What pathological mechanism causes the CT “fogging effect” during the second week of a cerebral infarct?
• A) Influx of lipid-laden macrophages, neoangiogenesis, and proteinaceous debris causing T1 shortening and attenuation increase
• B) Complete resolution of cytotoxic edema back to normal tissue density
• C) Massive calcification of the necrotic core
• D) Recanalization of the occluded parent artery
• Answer:A
• Explanation: Between days 7 and 14, macrophage infiltration and granulation tissue alter tissue attenuation, temporarily rendering the infarct isoattenuating on CT (the fogging effect).

Case 1.4: Watershed Infarction (Internal vs. Cortical)

• Scenario: A patient with severe systemic hypotension experiences bilateral watershed ischemia. MRI demonstrates wedge-shaped infarcts at the junction of the ACA and MCA territories.
• Question: What anatomical region is characteristically involved in internal watershed cerebral infarction?
• A) The pial surface between the frontal and parietal lobes
• B) The deep white matter centrum semiovale between the superficial MCA pial supply and deep lenticulostriate penetrating perforators
• C) The cerebellar hemispheres
• D) The interpeduncular cistern
• Answer:B
• Explanation: Internal watershed infarctions occur in the deep border zone between deep penetrating medullary arteries and superficial cortical pial branches.

Case 1.5: Cortical Laminar Necrosis

• Scenario: A patient evaluated weeks after severe carbon monoxide poisoning demonstrates ribbon-like hyperintensity along the cerebral cortical ribbon on T1-weighted MRI.
• Question: What histopathological substrate accounts for T1 hyperintensity in cortical laminar necrosis?
• A) Accumulation of gemistocytic astrocytes containing iron and lipid-laden macrophages with paramagnetic degradation products
• B) Extracellular calcium crystal deposition
• C) Acute erythrocyte extravasation forming deoxyhemoglobin
• D) Demyelination of subcortical U-fibers
• Answer:A
• Explanation: Cortical laminar necrosis results from selective neuronal death in cortical layers 3, 5, and 6. Subsequent macrophage activity and fat-laden glial cells produce pronounced T1 shortening.

Case 1.6: Hyperdense MCA Sign

• Scenario: A non-contrast head CT performed 45 minutes after acute stroke onset demonstrates high attenuation within the right Sylvian fissure MCA branches.
• Question: What does the hyperdense MCA sign represent on non-contrast CT?
• A) Calcified atheromatous plaque within the vessel wall
• B) Acute fresh intravascular thrombus or embolus within the lumen
• C) Contrast extravasation from prior angiography
• D) Intramural hematoma from carotid dissection
• Answer:B
• Explanation: A fresh, red blood cell-rich thrombus has a high attenuation coefficient (higher density than circulating blood), appearing as the hyperdense MCA or dot sign.

Case 1.7: Malignant MCA Infarction

• Scenario: A patient with a complete right MCA occlusion develops massive cerebral edema on day 2 post-stroke, causing uncal herniation and midline shift.
• Question: Within what clinical timeframe does malignant edema typically peak following a large hemispheric infarction?
• A) 1 to 3 hours
• B) 24 to 72 hours (3 to 5 days)
• C) 2 to 3 weeks
• D) 6 months
• Answer:B
• Explanation: Cytotoxic and vasogenic edema peaks between 3 to 5 days post-infarction, frequently necessitating emergent decompressive hemicraniectomy.

Case 1.8: Lacunar Infarction

• Scenario: A hypertensive patient presents with pure motor hemiparesis. MRI reveals a small (8 mm) cystic cavity in the posterior limb of the internal capsule.
• Question: What is the primary underlying vascular pathology of classic lacunar infarcts in the basal ganglia and internal capsule?
• A) Atheromatous plaque embolization from the carotid bifurcation
• B) Hypertensive lipohyalinosis and fibrinoid necrosis of small penetrating lenticulostriate arteries
• C) Giant cell arteritis
• D) Cerebral amyloid angiopathy
• Answer:B
• Explanation: Chronic hypertension causes lipohyalinosis, microatheroma formation, and fibrinoid necrosis of deep penetrating end-arteries, leading to small deep infarcts (lacunes).

Case 1.9: Pontine Infarction (Basilar Artery Occlusion)

• Scenario: A patient presents with acute quadriplegia and loss of horizontal gaze, retaining vertical eye movement and preserved consciousness (“locked-in” syndrome).
• Question: Occlusion of which major vessel and subsequent ischemia of which pontine structure produces the classic “locked-in” syndrome?
• A) Anterior cerebral artery; genu of the corpus callosum
• B) Basilar artery; ventral pons (interruption of corticospinal and corticobulbar tracts)
• C) Posterior inferior cerebellar artery; lateral medulla
• D) Middle cerebral artery; internal capsule
• Answer:B
• Explanation: Basilar artery occlusion infarcts the ventral pons, sparing the reticular activating system in the dorsal tegmentum while disrupting motor pathways.

Case 1.10: Cerebellar Infarction & Brainstem Compression

• Scenario: A patient with acute vertigo and ataxia develops depressed mental status. CT demonstrates a cerebellar hemisphere infarct with swelling compressing the fourth ventricle and causing obstructive hydrocephalus.
• Question: What is the most immediate neurosurgical priority when managing a massive cerebellar infarction with mass effect?
• A) Stereotactic radiosurgery
• B) Emergent suboccipital decompressive craniectomy and CSF diversion
• C) Endovascular coiling of the vertebral artery
• D) Systemic thrombolysis
• Answer:B
• Explanation: Cerebellar swelling can rapidly cause brainstem compression and tonsillar herniation through the foramen magnum, requiring emergent suboccipital decompression.

Case 1.11: PCA Infarction (Calcarine Cortex)

• Scenario: A patient presents with contralateral homonymous hemianopsia with macular sparing following a stroke.
• Question: Why is macular vision frequently spared in posterior cerebral artery (PCA) infarction involving the occipital lobe?
• A) Dual blood supply to the occipital pole from both the MCA and PCA pial collaterals
• B) The macula is represented in the anterior calcarine cortex
• C) The occipital pole (macular representation) receives collateral anastomoses from middle cerebral artery leptomeningeal branches
• D) The optic nerve bypasses the PCA territory entirely
• Answer:C
• Explanation: The occipital pole receives overlapping pial collateral supply from distal branches of the middle cerebral artery, sparing central macular vision during PCA occlusion.

Case 1.12: Dural Venous Sinus Thrombosis & Venous Infarction

• Scenario: A postpartum patient presents with seizures and headache. MRI reveals bilateral parasagittal hemorrhagic infarctions that cross standard arterial vascular boundaries.
• Question: What key imaging feature distinguishes venous infarctions from typical arterial ischemic strokes?
• A) Venous infarcts always involve the deep basal ganglia exclusively.
• B) Venous infarcts frequently cross arterial territories, are hemorrhagic, and are associated with lack of flow void in dural venous sinuses on MR venography.
• C) Venous infarcts never demonstrate restricted diffusion.
• D) Venous infarcts exclusively affect the brainstem.
• Answer:B
• Explanation: Cerebral venous thrombosis obstructs outflow, resulting in engorged veins, petechial hemorrhages, and edema that disregard arterial boundaries.

Case 1.13: Anterior Cerebral Artery (ACA) Infarction

• Scenario: A patient presents with contralateral abulia, leg-predominant motor weakness, and urinary incontinence.
• Question: Which ACA segment gives rise to the recurrent artery of Heubner, supplying the anterior limb of the internal capsule and head of the caudate?
• A) A1 segment (pre-communicating)
• B) A2 segment (post-communicating / infracallosal)
• C) A3 segment (precallosal)
• D) A5 segment (terminal cortical branch)
• Answer:A
• Explanation: The recurrent artery of Heubner arises near the A1/A2 junction, supplying critical deep gray and white matter structures.

Case 1.14: CADASIL

• Scenario: A young adult with a family history of early-onset stroke and migraine-like headaches undergoes brain MRI, revealing extensive confluent T2/FLAIR hyperintensity within the anterior temporal pole white matter and external capsules.
• Question: What gene mutation is responsible for CADASIL, and what is its inheritance pattern?
• A) NOTCH3 gene on chromosome 19q12, autosomal dominant
• B) HTT gene on chromosome 4p16.3, autosomal dominant
• C) SMN1 gene on chromosome 5q13, autosomal recessive
• D) VHL gene on chromosome 3p25, autosomal dominant
• Answer:A
• Explanation: CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) is caused by NOTCH3 mutations, classically affecting temporal pole and external capsule white matter.

Case 1.15: Reversible Cerebral Vasoconstriction Syndrome (RCVS)

• Scenario: A patient presents with recurrent “thunderclap” headaches. MRA of the brain demonstrates diffuse, segmental narrowing and dilation of intracranial arteries (“string of beads” appearance) that completely normalizes on repeat imaging at 12 weeks.
• Question: What is the hallmark clinical and angiographic course of RCVS?
• A) Progressive, irreversible arterial occlusion leading to massive hemispheric infarction within 48 hours
• B) Spontaneous resolution of clinical symptoms and normalization of angiographic vasospasm within 12 weeks
• C) Strict requirement for emergent surgical bypass of the circle of Willis
• D) Mandatory malignant transformation into primary CNS vasculitis
• Answer:B
• Explanation: RCVS is characterized by thunderclap headaches and multifocal cerebral vasoconstriction that resolves spontaneously within 1–3 months.

Case 1.16: Primary Angiitis of the Central Nervous System (PACNS)

• Scenario: A patient presents with subacute encephalopathy and multifocal strokes. Angiography reveals alternating segments of stenosis and ectasia restricted strictly to intracranial vessels, with negative systemic inflammatory markers.
• Question: How does PACNS differ angiographically and clinically from RCVS?
• A) PACNS features persistent, progressive angiographic narrowing and CSF inflammatory changes without spontaneous normalization, whereas RCVS resolves within weeks.
• B) PACNS exclusively affects extracranial carotid arteries.
• C) PACNS causes painless, acute-onset thunderclap headaches lasting under 5 minutes.
• D) PACNS is entirely benign and self-limiting without immunosuppression.
• Answer:A
• Explanation: Primary CNS vasculitis is a chronic, progressive inflammatory arteriopathy confined to the CNS, contrasting with the self-limited, transient vasospasm of RCVS.

Case 1.17: Fat Embolism Syndrome

• Scenario: Following a long-bone fracture, a patient develops petechial rash and neurological confusion. Brain MRI with SWI shows a “starfield” pattern of countless tiny punctate microhemorrhages and restricted diffusion throughout the cerebral white matter.
• Question: What pathognomonic MRI pattern characterizes cerebral fat embolism syndrome?
• A) A single large middle cerebral artery occlusion
• B) Diffuse “starfield” pattern of tiny punctate DWI hyperintensities and SWI microhemorrhages distributed throughout the white matter
• C) Isolated involvement of the pituitary gland and optic chiasm
• D) Symmetrical brainstem necrosis without hemispheric lesions
• Answer:B
• Explanation: Embolized fat globules occlude cerebral microvessels, producing the characteristic diffuse “starfield” punctate ischemic and hemorrhagic lesion pattern.

Case 1.18: Air Embolism / Decompression Sickness

• Scenario: Following central venous catheter removal, a patient collapses. CT brain demonstrates intravascular air within the cerebral cortical sulci and cavernous sinus.
• Question: What is the immediate mechanism of tissue injury in cerebral arterial gas embolism?
• A) Direct mechanical blockade of microvascular blood flow by gas bubbles coupled with local endothelial activation and ischemia
• B) Massive demyelination of the optic tracts
• C) Dystrophic calcification of the basal ganglia
• D) Primary rupture of berry aneurysms
• Answer:A
• Explanation: Gas bubbles lodge in cerebral arterioles, halting capillary perfusion and triggering acute ischemia and blood-brain barrier disruption.

Case 1.19: Neonatal Hypoxic-Ischemic Encephalopathy (Term vs. Preterm)

• Scenario: A term neonate born after acute placental abruption develops seizures. MRI demonstrates selective T2 hypointensity and restricted diffusion in the posterolateral putamen and ventrolateral thalami.
• Question: Why does acute profound asphyxia in term neonates target the basal ganglia and thalami?
• A) High metabolic rate and intense excitatory amino acid (glutamate) receptor density in maturing deep gray matter structures
• B) Complete absence of myelin in the internal capsule
• C) Exclusive arterial supply from the anterior cerebral artery
• D) Lower local body temperature
• Answer:A
• Explanation: Term infants subjected to acute profound hypoxia-ischemia sustain injury preferentially in metabolically active deep gray matter structures (thalami and basal ganglia).

Case 1.20: Periventricular Leukomalacia (PVL)

• Scenario: A premature infant imaged at term-equivalent age demonstrates ventriculomegaly with irregular contour and volume loss of the periventricular white matter, particularly at the trigones of the lateral ventricles.
• Question: What anatomical vulnerability explains why premature infants are uniquely susceptible to periventricular leukomalacia?
• A) Immature, vulnerable terminal medullary arteries supplying the watershed zones adjacent to the lateral ventricles
• B) Hypertrophy of the choroid plexus overproducing CSF
• C) Premature closure of the anterior fontanelle
• D) Excessive myelination of projection fibers
• Answer:A
• Explanation: Premature infants possess immature border-zone vasculature around the ventricles (periventricular arterial end-zones), rendering them susceptible to ischemic white matter injury (PVL).

Case 1.21: Moyamoya Disease

• Scenario: A young pediatric patient presents with transient ischemic attacks and progressive hemiparesis. Cerebral angiography demonstrates severe, progressive stenosis of the terminal internal carotid arteries and proximal anterior and middle cerebral arteries, accompanied by an extensive network of basal collateral vessels.
• Question: What classic angiographic appearance describes the fine collateral vessel network that develops at the base of the brain in Moyamoya disease?
• A) “String of beads” appearance
• B) “Puff of smoke” (moyamoya in Japanese) appearance representing dilated lenticulostriate collaterals
• C) “Corkscrew” collateral branches of the occipital artery
• D) “Basket” sign surrounding vascular tumors
• Answer: B
• Explanation: Chronic ICA occlusion prompts fragile, hazy collateral networks (the “puff of smoke” or moyamoya vessels) around the basal cisterns and basal ganglia.

Case 1.22: Wallenberg Syndrome (Lateral Medullary Syndrome)

• Scenario: A patient presents with acute vertigo, ipsilateral Horner syndrome, loss of pain and temperature sensation on the ipsilateral face and contralateral body, and hoarseness. MRI reveals a small infarct in the dorsolateral medulla.
• Question: Occlusion of which specific vessel is most commonly responsible for Wallenberg (lateral medullary) syndrome?
• A) Anterior inferior cerebellar artery (AICA)
• B) Posterior inferior cerebellar artery (PICA) or the parent vertebral artery
• C) Superior cerebellar artery (SCA)
• D) Anterior spinal artery
• Answer: B
• Explanation: Wallenberg syndrome results from ischemia in the territory of the PICA or the intracranial vertebral artery supplying the dorsolateral medulla.

Case 1.23: Medial Medullary Syndrome (Dejerine Syndrome)

• Scenario: A patient presents with contralateral hemiparesis, contralateral loss of proprioception/vibration, and ipsilateral tongue paralysis with deviation to the side of the lesion.
• Question: Occlusion of which penetrating vessel group causes medial medullary syndrome?
• A) Anterior spinal artery and paramedian branches of the vertebral artery
• B) Lateral lenticulostriate branches of the middle cerebral artery
• C) Heubner recurrent artery
• D) Thalamogeniculate perforators
• Answer: A
• Explanation: Medial medullary infarction involves the pyramidal tract, medial lemniscus, and hypoglossal nerve fibers, supplied by the anterior spinal and paramedian vertebral arteries.

Case 1.24: Weber Syndrome (Midbrain Stroke)

• Scenario: A patient presents with ipsilateral oculomotor nerve (CN III) palsy combined with contralateral hemiparesis. MRI confirms a ventral midbrain infarct.
• Question: Which anatomical structures within the cerebral peduncle are damaged to produce Weber syndrome?
• A) Corticospinal tracts and exiting fascicles of the third cranial nerve (CN III)
• B) Red nucleus and superior cerebellar peduncle
• C) Optic tract and lateral geniculate body
• D) Tectal plate quadrigeminal bodies
• Answer: A
• Explanation: Weber syndrome is a midbrain stroke involving the cerebral peduncle (corticospinal fibers) and the rootlets of cranial nerve III.

Case 1.25: Top of the Basilar Syndrome

• Scenario: A patient presents with abrupt visual disturbances (cortical blindness), abnormal ocular motility, and abrupt behavioral unresponsiveness without prominent motor weakness.
• Question: What structures are typically infarcted in “top of the basilar” syndrome due to embolization at the basilar bifurcation?
• A) Occipital lobes, thalami, rostral midbrain, and medial temporal lobes
• B) Frontal cortex and anterior corpus callosum exclusively
• C) Internal capsule and lentiform nucleus
• D) Cerebellar hemispheres and flocculonodular lobe
• Answer: A
• Explanation: The basilar bifurcation (“top of the basilar”) supplies the posterior cerebral arteries, superior cerebellar arteries, and thalamoperforating branches, resulting in ischemia of the occipital lobes, thalami, and midbrain.

Case 1.26: Hypoglycemic Encephalopathy

• Scenario: A patient presents in a deep coma following accidental insulin overdose. Brain MRI demonstrates symmetric restricted diffusion involving the cerebral cortex, basal ganglia, and hippocampi, with notable sparing of the thalami and brainstem.
• Question: How does the neuroimaging pattern of severe hypoglycemic encephalopathy classically differ from global hypoxic-ischemic encephalopathy (HIE)?
• A) Hypoglycemia characteristically spares the thalami and posterior fossa structures while prominently involving the cerebral cortex and basal ganglia; HIE frequently damages thalami.
• B) Hypoglycemia causes isolated spinal cord demyelination.
• C) Hypoglycemia produces uniform bilateral internal capsule infarction.
• D) Hypoglycemia exclusively affects the cerebellum.
• Answer: A
• Explanation: Severe hypoglycemia creates a metabolic energy crisis that selectively injures the neocortex and basal ganglia while sparing the thalami, distinguishing it from anoxic-ischemic encephalopathy.

Case 1.27: Wernicke Encephalopathy

• Scenario: A patient with chronic alcohol abuse and severe malnutrition presents with ophthalmoparesis, ataxia, and acute confusion. MRI demonstrates symmetric T2/FLAIR hyperintensity in the medial thalami, periaqueductal gray matter, and mammillary bodies.
• Question: What vitamin deficiency causes Wernicke encephalopathy, and what is the typical vascular/metabolic basis for regional vulnerability?
• A) Vitamin B1 (thiamine) deficiency; regions with high metabolic turnover and high local blood flow (periventricular/periaqueductal structures) are uniquely sensitive to ATP depletion.
• B) Vitamin B12 deficiency; localized to the dorsal columns of the spinal cord
• C) Niacin deficiency; localized to the motor strip
• D) Vitamin C deficiency; restricted to subcortical white matter
• Answer: A
• Explanation: Thiamine acts as an essential cofactor for critical Krebs cycle enzymes. Deficiency causes selective metabolic failure in high-demand periaqueductal and perithalamic gray matter.

Case 1.28: Extrapontine Myelinolysis (Osmotic Demyelination)

• Scenario: Following rapid correction of chronic hyponatremia, a patient develops movement disorders and extrapyramidal signs. MRI reveals symmetric T2 hyperintensity in the lateral geniculate bodies, putamen, and caudate nuclei, with a spared pons.
• Question: What pathological process underlies osmotic demyelination syndrome (central and extrapontine myelinolysis)?
• A) Rapid osmotic shifts causing breakdown of myelin sheaths and oligodendrocyte apoptosis without primary inflammatory cell infiltration
• B) Suppurative bacterial infection of deep gray matter
• C) Massive arterial infarction from basilar thrombosis
• D) Amyloid deposition within basal ganglia vessels
• Answer: A
• Explanation: Rapid correction of chronic hyponatremia creates an osmotic gradient that damages oligodendrocytes and strips myelin from axons in the pons and extrapontine sites (basal ganglia, thalamus).

Case 1.29: Sickle Cell Disease Stroke in Children

• Scenario: A pediatric patient with sickle cell anemia presents with acute hemiparesis. Transcrainal Doppler and MRA reveal high-velocity turbulence and severe stenosis of the distal internal carotid and proximal middle cerebral arteries.
• Question: What is the primary pathophysiological mechanism leading to cerebral infarction in pediatric sickle cell patients?
• A) Endothelial hyperplasia and intimal proliferation from chronic sickling and vessel wall damage, leading to progressive large vessel stenosis and secondary infarction
• B) Congenital absence of the circle of Willis
• C) Septic emboli originating from pulmonary infections
• D) Isolated deep venous sinus thrombosis
• Answer: A
• Explanation: Chronic hemolysis and sickle erythrocyte adhesion damage the endothelium of the terminal ICA and proximal MCA, causing smooth muscle proliferation, intimal thickening, and stenosis.

Case 1.30: Radiation-Induced Vasculopathy (Moyamoya-like Syndrome)

• Scenario: A patient treated with cranial radiation for a medulloblastoma during childhood develops progressive ischemic strokes 10 years later. Angiography reveals smooth narrowing of the supraclinoid internal carotid arteries with extensive collateral network formation.
• Question: What distinguishes radiation-induced intracranial vasculopathy from congenital Moyamoya disease?
• A) Radiation vasculopathy features a history of prior therapeutic irradiation, later age of onset, and often more extensive involvement of proximal intracranial trunks with unique soft-tissue changes.
• B) Radiation vasculopathy never forms collateral vessels.
• C) Congenital Moyamoya disease exclusively occurs after age 50.
• D) Radiation vasculopathy responds instantly to oral antibiotics.
• Answer: A
• Explanation: Cranial irradiation induces progressive endothelial damage, smooth muscle cell depletion, and accelerated atherosclerosis/fibrosis, mimicking Moyamoya arteriopathy years after treatment.

Case 1.31: Cerebral Venous Sinus Thrombosis (CVST) with Cortical Infarction

• Scenario: A young adult presents with headache, papilledema, and focal motor seizures. Non-contrast CT demonstrates a hyperdense right transverse sinus. MRI reveals a right parietal hemorrhagic venous infarction crossing arterial boundaries.
• Question: What is the primary hemodynamic consequence of cerebral venous sinus outflow obstruction?
• A) Immediate arterial vasospasm followed by normalization
• B) Elevation of capillary and venular pressure, breakdown of the blood-brain barrier, decreased cerebral perfusion pressure, and subsequent vasogenic/cytotoxic edema with hemorrhage
• C) Complete cessation of arterial inflow to the entire brain
• D) Hypertrophy of the circle of Willis
• Answer: B
• Explanation: Thrombosis of dural sinuses impedes venous drainage, raising back-pressure in capillary beds, leading to venous ischemia, hemorrhagic transformation, and edema.

Case 1.32: CADASIL (Detailed White Matter Distribution)

• Scenario: Genetic screening confirms CADASIL in a patient with recurrent ischemic strokes and cognitive decline.
• Question: Beyond the anterior temporal pole white matter, which other subcortical white matter region is characteristically and prominently involved in CADASIL?
• A) External capsule
• B) Calcarine cortex primary visual strip
• C) Medullary pyramids of the brainstem
• D) Optic chiasm
• Answer: A
• Explanation: The external capsule and anterior temporal pole white matter are classic, highly sensitive radiological signposts for CADASIL on T2/FLAIR MRI.

Case 1.33: Susac Syndrome (Ischemic White Matter / Corpus Callosum)

• Scenario: A young female presents with encephalopathy, branch retinal artery occlusions, and sensorineural hearing loss. Sagittal FLAIR MRI reveals characteristic punched-out central lesions within the body of the corpus callosum.
• Question: Why do callosal lesions in Susac syndrome characteristically involve the central core rather than the ependymal/inferior margins?
• A) The central microvasculature of the corpus callosum (supplied by the pericallosal branches) undergoes immune-mediated occlusion of precapillary arterioles.
• B) The ependymal surface protects the central fibers.
• C) Cerebrospinal fluid exerts mechanical compression on the edges.
• D) Demyelinating plaques always select the central core.
• Answer: A
• Explanation: Susac syndrome is an immune-mediated endotheliopathy targeting precapillary arterioles, producing microinfarcts in the central microvascular watershed of the corpus callosum.

Case 1.34: Post-Partum Angiopathy (RCVS Variant)

• Scenario: A postpartum female presents with sudden severe headache and focal neurological deficits. MR angiography demonstrates multifocal narrowing of intracranial arteries that resolves completely on follow-up imaging at 6 weeks.
• Question: What triggers are commonly implicated in triggering Reversible Cerebral Vasoconstriction Syndrome (RCVS) during the postpartum period?
• A) Exposure to vasoactive substances (e.g., SSRIs, triptans, sympathomimetics) or physiological hormonal shifts in the puerperium
• B) Severe chronic bacterial sinusitis
• C) Iron deficiency anemia
• D) Elevated serum calcium levels
• Answer: A
• Explanation: RCVS is frequently triggered in postpartum women by endogenous hormonal changes or exposure to vasoactive medications (such as selective serotonin reuptake inhibitors or decongestants).

Case 1.35: Cholesterol Embolism Syndrome

• Scenario: Following cardiac catheterization, a patient develops livedo reticularis, acute renal failure, and confusion. Brain MRI demonstrates multiple scattered small acute microinfarcts in both anterior and posterior circulations.
• Question: What is the histopathological source of emboli in cholesterol crystal embolism syndrome?
• A) Atheromatous plaque disruption within the thoracic or abdominal aorta releasing cholesterol crystals into systemic arterial flow
• B) Thrombus formation inside the left atrial appendage
• C) Vegetation on the mitral valve
• D) Deep venous thrombosis via a patent foramen ovale
• Answer: A
• Explanation: Instrumentation of a diseased aorta dislodges atheromatous plaque debris and cholesterol crystals, which shower the microvasculature of visceral organs and the brain.

Case 1.36: Hereditary Endotheliopathy with Retinopathy, Nephropathy, and Stroke (HERNS)

• Scenario: A patient with a family history of early strokes, retinal blindness, and renal failure undergoes brain MRI, showing multifocal white matter infarctions and encephalomalacia.
• Question: What characterizes the genetic and vascular pathophysiology of HERNS syndrome?
• A) Mutations in the TREX1 gene leading to systemic vascular endotheliopathy and microvascular thrombosis
• B) Trinucleotide repeats on chromosome 4
• C) Mitochondrial point mutations at position 3243
• D) Autosomal recessive lysosomal storage defect
• Answer: A
• Explanation: HERNS (and related retinal vasculopathy with cerebral leukodystrophy – RVCL) stems from TREX1 mutations causing systemic microvascular degeneration and multi-organ ischemic infarction.

Case 1.37: Fabry Disease Stroke

• Scenario: A young male presents with stroke, angiokeratomas, and peripheral neuropathy. Brain MRI reveals dolichoectasia of the vertebrobasilar system and multifocal white matter and lacunar infarcts.
• Question: What is the underlying biochemical defect and inheritance pattern of Fabry disease?
• A) X-linked recessive deficiency of alpha-galactosidase A, leading to intracellular accumulation of globotriaosylceramide ($GL_3$) in endothelial and smooth muscle cells
• B) Autosomal dominant deficiency of beta-glucosidase
• C) Autosomal recessive hexosaminidase A deficiency
• D) X-linked dominant copper transport defect
• Answer: A
• Explanation: Fabry disease is an X-linked lysosomal storage disorder caused by alpha-galactosidase A deficiency, resulting in glycolipid deposition within vascular walls, causing premature stroke and dolichoectasia.

Case 1.38: MELAS Stroke-Like Episodes (Cytotoxic vs. Vasogenic Edema)

• Scenario: A young patient with a mitochondrial mutation presents with acute stroke-like episodes. Unlike typical arterial infarcts, MRI demonstrates cortical T2 hyperintensity and restricted diffusion that crosses arterial boundaries, with prominent perfusion-diffusion mismatch (high rCBV).
• Question: What distinguishes the pathophysiology of a MELAS “stroke-like episode” from a classic thromboembolic ischemic stroke?
• A) MELAS lesions are caused by mitochondrial cytopathy-induced metabolic failure and localized arteriolar dysfunction (mitochondrial angiopathy), resulting in vasogenic/cytotoxic edema that crosses vascular territories, rather than large-vessel occlusion.
• B) MELAS strokes are exclusively caused by cardiac myxomas.
• C) MELAS lesions never demonstrate restricted diffusion.
• D) MELAS strokes are treated exclusively with surgical embolectomy.
• Answer: A
• Explanation: MELAS stroke-like episodes reflect mitochondrial metabolic failure and arteriolar dysfunction rather than embolic occlusion, often showing elevated perfusion (hyperperfusion/high rCBV).

Case 1.39: Susac Syndrome vs. Multiple Sclerosis

• Scenario: A patient presents with white matter lesions and cognitive impairment. Differential diagnosis includes multiple sclerosis and Susac syndrome.
• Question: Which MRI finding strongly favors Susac syndrome over multiple sclerosis?
• A) Involvement of the central corpus callosum with sparing of the inferior callosal surface, combined with branch retinal artery occlusions
• B) Dawson fingers perpendicular to the lateral ventricles
• C) Open-ring contrast enhancement in subcortical white matter
• D) Complete resolution of all brain lesions within 48 hours
• Answer: A
• Explanation: Central callosal microinfarctions (“snowballs”) and retinal artery occlusions are the diagnostic hallmarks distinguishing Susac syndrome from multiple sclerosis.

Case 1.40: Cerebral Amyloid Angiopathy (CAA) – Related Inflammation (CAA-ri)

• Scenario: An elderly patient presents with rapidly progressive cognitive decline, seizures, and headache. MRI reveals asymmetric confluent white matter edema and multiple lobular microhemorrhages on gradient echo / SWI sequences.
• Question: What pathological process underlies cerebral amyloid angiopathy-related inflammation (CAA-ri)?
• A) An autoimmune inflammatory response directed against beta-amyloid peptide deposition within cerebral blood vessel walls (perivascular inflammation)
• B) Acute bacterial infection tracking along Virchow-Robin spaces
• C) Direct neoplastic infiltration by glioblastoma cells
• D) Post-traumatic axonal shearing
• Answer: A
• Explanation: CAA-ri represents an autoimmune inflammatory vasculopathy directed against amyloid-beta aggregates in leptomeningeal and cortical vessel walls, presenting with vasogenic edema and microbleeds.

Module 1: Ischemia, Stroke & Hypoxic-Ischemic Insult (Cases 41–60)

Case 1.41: CARASIL (Cerebral Autosomal Recessive Arteriopathy with Subcortical Infarcts and Leukoencephalopathy)

• Scenario: A young adult presents with progressive cognitive decline, gait disturbance, early-onset severe spondylosis of the spine, and alopecia. Brain MRI demonstrates diffuse deep white matter T2/FLAIR hyperintensities and multiple lacunar infarcts.
• Question: What gene mutation distinguishes CARASIL from CADASIL?
• A) NOTCH3 gene on chromosome 19q12 (autosomal dominant)
• B) HTRA1 gene on chromosome 10q26 (autosomal recessive), encoding a serine protease that regulates TGF-beta signaling
• C) TREX1 gene on chromosome 3p21
• D) GLA gene on the X chromosome
• Answer: B
• Explanation: While CADASIL is autosomal dominant due to NOTCH3 mutations, CARASIL is an autosomal recessive arteriopathy caused by mutations in HTRA1, clinically featuring early spondylosis and alopecia alongside stroke.

Case 1.42: Sneddon Syndrome

• Scenario: A young female presents with livedo reticularis on her skin and recurrent ischemic strokes. Brain MRI shows multiple small ischemic lesions in the middle cerebral artery territories.
• Question: What laboratory finding or antibody is frequently associated with Sneddon syndrome, linking it to thrombotic risk?
• A) Anticardiolipin antibodies and lupus anticoagulant (antiphospholipid syndrome spectrum)
• B) Elevated serum uric acid
• C) Positive anti-neutrophil cytoplasmic antibodies (ANCA)
• D) Depleted C1 esterase inhibitor
• Answer: A
• Explanation: Sneddon syndrome is characterized by non-inflammatory thrombosis of medium-sized arteries associated with livedo reticularis, frequently linked to antiphospholipid antibodies.

Case 1.43: Fibromuscular Dysplasia (FMD) of the Cervical ICA

• Scenario: A middle-aged female presents with a Horner syndrome and cervical bruit. CTA reveals alternating segments of mural thinning/aneurysmal dilation and web-like stenoses along the mid-cervical internal carotid artery.
• Question: What is the classic angiographic description of medial fibroplasia, the most common subtype of fibromuscular dysplasia?
• A) “String of beads” appearance (alternating areas of mural web stenosis and aneurysmal mural dilation)
• B) “Corkscrew” tortuosity without lumen caliber change
• C) Smooth, long-segment concentric tapering
• D) Complete cut-off of the common carotid bifurcation
• Answer: A
• Explanation: Medial fibroplasia accounts for the majority of FMD cases, producing the classic angiographic “string of beads” sign in the mid-to-distal cervical ICA or renal arteries.

Case 1.44: Posterior Reversible Encephalopathy Syndrome (PRES)

• Scenario: A patient with acute severe hypertension and preeclampsia presents with headache, visual disturbances, and seizures. MRI demonstrates symmetric T2/FLAIR hyperintensity localized predominantly to the parieto-occipital subcortical white matter without restricted diffusion.
• Question: What is the primary pathophysiological mechanism underlying vasogenic edema in PRES?
• A) Severe autoregulatory breakthrough in cerebral blood flow when systemic blood pressure exceeds upper autoregulatory limits, causing capillary hydrostatic pressure elevation and blood-brain barrier breakdown (predominantly in the posterior circulation due to sparse sympathetic innervation)
• B) Cytotoxic cell death from direct viral neurotoxicity
• C) Primary arterial occlusion of the basilar trunk
• D) Venous sinus thrombosis causing back-pressure edema
• Answer: A
• Explanation: Acute hypertension exceeds autoregulation, forcing plasma across tight junctions into the extravascular space (vasogenic edema), with a predilection for parietal and occipital lobes.

Case 1.45: Cerebral Venous Sinus Thrombosis (The “Empty Delta Sign”)

• Scenario: A patient with dural sinus thrombosis undergoes contrast-enhanced brain CT. Axial images through the posterior fossa reveal a filling defect within the superior sagittal sinus surrounded by enhancing collateral dural channels.
• Question: What is the “empty delta sign” on contrast-enhanced CT or MRI in cerebral venous thrombosis?
• A) A triangular filling defect in the thrombus-occluded superior sagittal sinus surrounded by enhancing collateral dura
• B) Complete absence of the straight sinus
• C) Air-fluid levels within the transverse sinus
• D) Thrombosis of the internal jugular bulb
• Answer: A
• Explanation: The empty delta sign represents unenhanced thrombus in the center of the superior sagittal sinus surrounded by enhancing dural leaves and collateral channels on post-contrast scans.

Case 1.46: Transient Global Amnesia (TGA)

• Scenario: A middle-aged patient experiences an abrupt episode of anterograde amnesia lasting several hours, with full subsequent recovery. Diffusion-weighted MRI obtained 48 hours later reveals tiny, punctate, highly specific focal restricted diffusion lesions in the lateral hippocampus (CA1 region).
• Question: What is the current leading pathophysiological hypothesis for transient global amnesia (TGA)?
• A) Venous congestion and transient ischemia within the hippocampal CA1 pyramidal neurons triggered by venous reflux (e.g., jugular valve incompetence during Valsalva-like maneuvers)
• B) Permanent atheromatous occlusion of the posterior cerebral artery
• C) Rupture of a berry aneurysm in the anterior communicating artery
• D) Chronic demyelinating plaque formation
• Answer: A
• Explanation: TGA is strongly linked to venous congestion in the hippocampi due to internal jugular vein valve incompetence, resulting in delayed, punctate DWI lesions in the CA1 sector.

Case 1.47: Amyloid-beta Related Angiitis (ABRA)

• Scenario: An elderly patient presents with progressive cognitive decline and focal deficits. MRI shows asymmetric confluent white matter hyperintensities and leptomeningeal enhancement. Biopsy reveals transmural inflammation around amyloid-laden cortical vessels.
• Question: How does ABRA differ pathologically from standard sporadic cerebral amyloid angiopathy (CAA)?
• A) ABRA features prominent granulomatous or lymphocytic perivascular inflammation directed against vascular amyloid deposits, whereas sporadic CAA lacks marked inflammatory infiltrates.
• B) ABRA exclusively affects deep gray matter structures.
• C) ABRA is an autosomal dominant congenital genodermatosis.
• D) ABRA never shows microhemorrhages on SWI.
• Answer: A
• Explanation: Amyloid-beta related angiitis (ABRA) is an inflammatory subtype of CAA characterized by transmural or perivascular granulomatous/lymphocytic inflammation responding to immunosuppression.

Case 1.48: Status Epilepticus-Induced Cytotoxic Edema

• Scenario: A patient presents with prolonged focal status epilepticus. MRI demonstrates restricted diffusion and cortical T2 hyperintensity confined strictly to the pulvinar of the thalamus and the ipsilateral hippocampus / neocortex involved by seizure activity.
• Question: Why does prolonged seizure activity cause restricted diffusion on DWI that can mimic an acute stroke?
• A) Extreme neuronal hypermetabolism exhausts cellular ATP stores, causing transient cytotoxic edema that is typically reversible following seizure cessation.
• B) Permanent infarction from mechanical arterial compression
• C) Massive extravasation of intravascular contrast media
• D) Demyelination of projection tracts
• Answer: A
• Explanation: Intense metabolic demand during status epilepticus triggers temporary energy failure and cytotoxic edema (pseudostroke), which usually resolves radiologically and clinically.

Case 1.49: Carbon Monoxide Poisoning (Globus Pallidus Necrosis)

• Scenario: A patient rescued from a house fire presents with lethargy and Parkinsonian signs. Brain MRI demonstrates bilateral, symmetric necrosis and restricted diffusion localized strictly to the globus pallidus.
• Question: Why is the globus pallidus uniquely susceptible to carbon monoxide and hypoxic-ischemic injury?
• A) It possesses high metabolic activity coupled with a vulnerable watershed blood supply from terminal lenticulostriate branches and high iron content.
• B) It is the only structure containing myelin.
• C) It receives direct arterial blood from the superior cerebellar artery.
• D) It lacks a blood-brain barrier.
• Answer: A
• Explanation: The globus pallidus is exceptionally sensitive to anoxic and toxic insults (like CO and cyanide) due to its high metabolic rate, iron concentration, and terminal vascular architecture.

Case 1.50: Methanol Intoxication (Putaminal Necrosis & Hemorrhage)

• Scenario: An adult who ingested bootleg alcohol presents with profound metabolic acidosis and acute blindness. Brain MRI reveals bilateral, symmetric necrosis and hemorrhagic infarction of the putamen.
• Question: What is the primary toxic metabolite responsible for basal ganglia necrosis and retinal toxicity in methanol poisoning?
• A) Formic acid (produced via formaldehyde oxidation)
• B) Acetaldehyde
• C) Ethylene glycol crystal precipitation
• D) Acetone accumulation
• Answer: A
• Explanation: Methanol is metabolized by alcohol dehydrogenase to formaldehyde and subsequently to formic acid, which accumulates, causing metabolic acidosis, retinal damage, and bilateral putaminal necrosis/hemorrhage.

Case 1.51: Penumbra Evaluation & Perfusion Mismatch

• Scenario: An acute stroke patient undergoes perfusion CT imaging. Cerebral blood flow (CBF) map shows a small core of dead tissue, while the mean transit time (MTT) and Tmax maps show a large surrounding area of hypoperfusion.
• Question: What does the “perfusion-diffusion mismatch” or “CBF-MTT mismatch” represent in acute stroke imaging?
• A) The ischemic penumbra—salvageable ischemic tissue surrounding the irreversibly injured core that can be rescued by prompt reperfusion therapy.
• B) Complete, irreversible pan-hemispheric infarction.
• C) Artifactual error caused by patient head motion.
• D) Normal baseline physiological brain perfusion.
• Answer: A
• Explanation: The mismatch area between the core (low CBF) and hypoperfused tissue at risk (prolonged MTT/Tmax) defines the salvageable ischemic penumbra.

Case 1.52: Alberta Stroke Program Early CT Score (ASPECTS)

• Scenario: An emergency non-contrast head CT is evaluated for a patient being considered for mechanical thrombectomy in an acute left MCA stroke.
• Question: In the 10-point ASPECTS grading system for anterior circulation ischemia, how many cortical regions are evaluated alongside the subcortical structures?
• A) 6 cortical regions (M1 through M6) and 4 subcortical regions (caudate, lentiform, internal capsule, insular cortex).
• B) 8 cortical regions and 2 subcortical regions.
• C) 10 cortical regions with zero subcortical points.
• D) Exactly 3 lobar regions.
• Answer: A
• Explanation: ASPECTS divides the MCA territory into 10 distinct regions: 6 cortical (M1-M6) and 4 subcortical (caudate, lentiform, internal capsule, insular ribbon), subtracting 1 point for each region showing hypoattenuation.

Case 1.53: Spontaneous Intracranial Hypotension (SIH) & Pachymeningeal Enhancement

• Scenario: A patient presents with severe orthostatic headaches (worse when upright, relieved by lying flat). Brain MRI reveals diffuse smooth pachymeningeal enhancement, pituitary hyperemia, and descent of the brain.
• Question: What physiological phenomenon causes diffuse pachymeningeal enhancement and subdural hygromas in intracranial hypotension?
• A) Compensatory dilation of dural meningeal veins and venous sinuses in response to CSF volume depletion ( Monro-Kellie doctrine compensation).
• B) Bacterial infection of the leptomeninges.
• C) Neoplastic infiltration of the skull base.
• D) Arterial vasodilation of the circle of Willis.
• Answer: A
• Explanation: Loss of CSF volume lowers intracranial pressure; the Monro-Kellie doctrine dictates that vascular structures (especially dural veins) dilate to compensate, causing smooth dural enhancement.

Case 1.54: Brain Death Imaging (CTA “Empty Lumen Sign”)

• Scenario: Confirmatory imaging is requested to establish brain death in a comatose patient. CT angiography of the brain demonstrates non-visualization of intracranial arterial branches (internal carotid arteries beyond the skull base, anterior and middle cerebral arteries, and internal cerebral veins).
• Question: What physiological state causes the “empty lumen sign” or arrest of intracranial contrast filling on brain death CTA?
• A) Intracranial pressure exceeding mean arterial pressure, halting cerebral perfusion and causing intravascular contrast arrest at the skull base.
• B) Complete surgical ligation of the common carotid arteries.
• C) Massive vasospasm restricted to extracranial vessels.
• D) Intravenous contrast extravasation into the scalp.
• Answer: A
• Explanation: When intracranial pressure rises above systemic arterial pressure, cerebral perfusion ceases, resulting in a failure of contrast to ascend past the skull base on CTA.

Case 1.55: Binswanger Disease (Subcortical Ischemic Leukoencephalopathy)

• Scenario: An elderly hypertensive patient presents with progressive vascular dementia, pseudobulbar palsy, and gait apraxia. MRI reveals extensive confluent deep white matter T2/FLAIR hyperintensity with relative sparing of U-fibers and multiple basal ganglia lacunes.
• Question: What is the primary underlying vascular pathology of Binswanger disease?
• A) Chronic systemic hypertension causing severe arteriolosclerosis, lipohyalinosis, and hyaline thickening of small medullary penetrating arteries, leading to chronic diffuse ischemia and demyelination.
• B) Amyloid plaque deposition within cortical veins.
• C) Genetic lysosomal enzyme deficiency.
• D) Autoimmune demyelination mimicking multiple sclerosis.
• Answer: A
• Explanation: Binswanger disease is a severe form of small-vessel vascular dementia driven by chronic hypertensive arteriolosclerosis of subcortical medullary white matter arteries.

Case 1.56: Susac Syndrome vs. Acute Disseminated Encephalomyelitis (ADEM)

• Scenario: A patient presents with acute encephalopathy and white matter lesions. Diagnostic workup differentiates between Susac syndrome and ADEM.
• Question: Which clinical feature helps distinguish Susac syndrome from ADEM or multiple sclerosis?
• A) The mandatory clinical triad of encephalopathy, branch retinal artery occlusions (BRAO), and sensorineural hearing loss.
• B) Monophasic post-viral encephalopathy in children.
• C) Exclusive spinal cord involvement with complete brain sparing.
• D) Elevated oligoclonal bands without retinal findings.
• Answer: A
• Explanation: The triad of encephalopathy, hearing loss, and branch retinal artery occlusions (BRAO) is pathognomonic for Susac microvascular endotheliopathy.

Case 1.57: Radiation-Induced Leigh Syndrome (Mitochondrial Encephalopathy)

• Scenario: A pediatric patient who received cranial radiation presents with developmental regression and symmetric bilateral necrosis of the basal ganglia and brainstem.
• Question: How does radiation-induced Leigh-like encephalopathy manifest radiologically?
• A) Symmetric, bilateral T2 hyperintensity and necrosis restricted to the basal ganglia (putamen/caudate) and brainstem tegmentum, resembling mitochondrial cytopathy.
• B) Unilateral fronto-temporal meningioma formation.
• C) Diffuse cortical laminar calcification without deep gray matter involvement.
• D) Isolated cerebellar vermis aplasia.
• Answer: A
• Explanation: High-dose radiation can disrupt mitochondrial oxidative phosphorylation enzymes in vulnerable children, producing a Leigh-like metabolic encephalopathy with symmetric deep gray matter necrosis.

Case 1.58: Amyloid Angiopathy with Superficial Siderosis

• Scenario: An elderly patient with recurrent lobar intracerebral hemorrhages undergoes gradient echo MRI, revealing profound hypointensity coating the cerebral sulci, gyral summits, and cerebellar folia.
• Question: What is the source of bleeding in cortical superficial siderosis associated with cerebral amyloid angiopathy?
• A) Chronic, recurrent microhemorrhages from amyloid-weakened pial and leptomeningeal vessels leaking directly into the subarachnoid space.
• B) Rupture of deep lenticulostriate aneurysms.
• C) Chronic thrombosis of the superior sagittal sinus.
• D) Elevated cerebrospinal fluid pressure tearing bridging veins.
• Answer: A
• Explanation: CAA weakens fragile leptomeningeal arteries over the convexities, leading to repeated micro-bleeds into the subarachnoid space, leaving hemosiderin deposits (superficial siderosis).

Case 1.59: CADASIL vs. Migraine with Aura

• Scenario: A young adult presents with migraine-like headaches with aura and recurrent transient ischemic attacks. MRI reveals anterior temporal pole white matter changes.
• Question: What key imaging and clinical features differentiate CADASIL-related ischemic attacks from typical migraine with aura?
• A) CADASIL patients show confluent subcortical white matter and temporal pole lesions on MRI and progressive cognitive decline, whereas typical migraineurs have normal structural brain MRI.
• B) CADASIL headaches are strictly unilateral and last under 10 minutes.
• C) Migraine aura always causes permanent cortical infarction.
• D) CADASIL symptoms resolve completely without any white matter scarring.
• Answer: A
• Explanation: While CADASIL patients frequently experience migraine-like auras, the presence of extensive subcortical and temporal pole white matter hyperintensities on MRI distinguishes genetic arteriopathy from primary migraine.

Case 1.60: Reversible Cerebral Vasoconstriction Syndrome (RCVS) Complications

• Scenario: A patient with RCVS and thunderclap headaches develops sudden acute right-sided weakness. Follow-up imaging shows a new watershed ischemic infarction and convexity subarachnoid hemorrhage.
• Question: What are the two most common secondary intracranial complications of Reversible Cerebral Vasoconstriction Syndrome (RCVS)?
• A) Convexity subarachnoid hemorrhage (cSAH) and ischemic or hemorrhagic stroke secondary to intense arterial constriction.
• B) Diffuse meningitis and spinal cord compression.
• C) Pituitary apoplexy and diabetes insipidus.
• D) Communicating hydrocephalus requiring ventricular shunting.
• Answer: A
• Explanation: RCVS frequently complicates its course with small convexity subarachnoid hemorrhages (from rupture of constricted pial vessels) and ischemic or secondary hemorrhagic strokes.