HYPERTENSIVE ENCEPHALOPATHY

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1 HYPERTENSIVE ENCEPHALOPATHY Reversible posterior leukoencephalopathy syndrome Cause Renal disease Pheochromocytoma Disseminated vasculitis Eclampsia Acute toxemia Medications & illicit drugs (cocaine) Discontinuation of hypertensive medications Disruption of BBB vasogenic edema Vascular fibrinoid necrosis hemorrhages

2 Adams & Victor s Principles of Neurology, 9th edition, 2009

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4 CHRONIC HYPERTENSION Atherosclerosis & microatheroma Lacunar infarcts Arteriolarsclerosis Subcortical ischemic vascular dementia Fibrinoid necrosis Bleeding?Microaneurysms (Charcot Bouchard aneurysms) Bleeding Ferrer I, et al: Vascular Diseases. In: Greenfield s Neuropathology, 8 th edition, 2008

5 Lacunar Infarct Less than 15 mm in diameter Occlusion of terminal arteries Arteriolarsclerosis Embolism Narrowing of ostium at site of origin

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8 Trichrome

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10 AMYLOID ANGIOPATHIES Sporadic or AD-associated Familial AD HCHWA-D HCHWA-I Meningovascular amyloidosis Familial amyloidosis, Finnish type Familial British dementia Familial Danish dementia Prion disease Amyloid beta Amyloid beta Amyloid beta Cystain C Transthyretin Gelsolin ABri ADan APrion protein Ellison D, et al. Neuropathology, 3 rd edition. 2013

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12 Congo red Beta amyloid Beta amyloid

13 CADASIL Cerebral autosomal dominant artheriopathy with subcortical infarcts and leukoencephalopathy Clinically associated with migraine, recurrent strokes, psychiatric symptoms & dementia Linked to mutations in the NOCHT 3 gene on chromosome 19 Related to deposits of PAS positive granular material in the tunica media of arteries of the CNS, skin, skeletal muscle and peripheral nerve Demyelination of centrum semiovale Lacunar infarcts in white matter, basal ganglia, thalamus and brain stem

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15 PAS PAS

16 Courtesy Dr. D. Louis, Boston, MA

17 Brain Ischemia Arterial cerebral blood flow is insufficient to maintain cellular functions Normal CBF: 55 ml/100g/min Moderate ischemia: CBF 15-20ml/100g/min Short duration <30 min Reversible cell injury Severe ischemia: CBF 10 ml/100g/min Irreversible cell injury

18 Brain Ischemia Regional ischemia: Pancellular necrosis Anemic infarct Hemorrhagic infarct Lacunar infarct Microscopic infarct Incomplete infarct Global ischemia Selective neuronal necrosis

19 Brain Infarct Gross Findings Recent (acute) Infarct 8-38 hours Blurring of gray/white matter junction Dusky gray discoloration of neural tissue Tissue softening on palpation 2-4 days Edema Organizing (subacute) infarct 5-30 days Liquefactive necrosis Organized (chronic) infarct >1 month Cystic cavity Modified from Ellison D, et al. Neuropathology, 3 rd edition. 2013

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23 Hemorrhagic Infarct Result from hemorrhagic transformation of ischemic lesion Mechanism Reperfusion of ischemic territory Episodes of hypertension Partial occlusion of arterial lumen Pathologic features Cortical petechial hemorrhages Hematoma

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25 BRAIN INFARCT MICROSCOPIC FINDINGS Recent (acute) infarct 1-4 days Neuronal eosinophilia Edema Acute inflammation Organizing (subacute) infarct 5-30 days Necrosis Macrophages Neovascularization Organized (chronic) infarct >1 month Gliosis at periphery of cavity Few macrophages Mineralized neurons Spheroids Preservation of cortical molecular layer Modified from Ellison D, et al. Neuropathology, 3 rd edition. 2013

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29 GLOBAL ISCHEMIA Terminology Diffuse anoxic/hypoxic -ischemic encephalopathy Anoxic/hypoxic brain injury Respirator brain Non-perfused brain Liquefied brain Transient: If blood flow to the brain is restored. Associated with selective neuronal necrosis Permanent: If blood flow to the brain is not restored. Associated with total brain necrosis

30 TRANSIENT GLOBAL ISCHEMIA Modifying factors Duration of ischemic episode Severity of ischemia Body temperature Hypothermia is protective Blood glucose level Hyperglycemia worsens outcome

31 GLOBAL BRAIN ISCHEMIA CAUSES Cardiac pathology Cardiac arrest Hypotension Shock Seizures including status epilepticus Intoxications (drug abuse) Increased intracranial pressure Traumatic brain injury Intracranial space occupying lesion

32 SELECTIVE VULNERABILITY Refers to differential susceptibility of CNS regions to a hypoxic-ischemic event Hippocampus: CA1 field (Summer sector) Cerebral cortex: Neurons in laminae 3 & 5 Cerebellum: Purkinje cells In premature and term infants, neuronal susceptibility differs from that in adults

33 GLOBAL ANOXIC-ISCHEMIC ENCEPHALOPATHY Gross acute/ subacute changes Generalized dusky discoloration, edema and softening Patchy gray discoloration of cortex with blurring of white and gray matter junction Watershed infarcts Cortical laminar or pancortical necrosis Bilateral hemorrhagic/ischemic necrosis of basal ganglia/thalamus Liquefaction necrosis Normal brain

34 24-year-old female Drug use Found unresponsive in bathroom Dx: Anoxic brain injury Survived 6 days

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40 GLOBAL ANOXIC-ISCHEMIC BRAIN INJURY Macroscopic chronic changes Diffuse or focal brain atrophy Watershed infarcts Cystic, bilateral, and symmetric necrosis of basal ganglia/ thalamus Hippocampal atrophy due to sclerosis Granular cerebral cortical atrophy related to watershed infarct Leukoencephalopathy Normal brain

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42 32-year-old male Schizophrenia Seizures Died in hospital

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45 Sir Thomas Willis ( ) Otto Binswanger, M.D. ( ) C. Miller Fisher, M. D. ( )