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Objectives for NS 2:

Objectives for NS 2:. You should be able to define, describe pathogenesis, list lesions and know how to diagnose the following conditions:. Cytotoxic, osmotic and vasogenic brain edema) Thiamine-responsive polioencephalomalacia of ruminants Thiamine deficiency in carnivores Lead poisoning

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Objectives for NS 2:

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  1. Objectives for NS 2: You should be able to define, describe pathogenesis, list lesions and know how to diagnose the following conditions: • Cytotoxic, osmotic and vasogenic brain edema) • Thiamine-responsive polioencephalomalacia of ruminants • Thiamine deficiency in carnivores • Lead poisoning • Salt poisoning • Toxin-induced vasogenic brain edema

  2. Response to injury - Brain edema Brain swelling (cerebral edema) Increased intracranial pressure E. Simko WCVM

  3. Response to injury - Brain edema Brain swelling (edema) Blood perfusion pressure Intracranial pressure Ischemic necrosis E. Simko WCVM

  4. Response to injury - Brain edema Brain edema • Cytotoxic (intracellular) • Extra cellular edema • Osmotic • Vasogenic E. Simko WCVM

  5. Response to injury - Brain edema Diagnosis: • Gross: • cerebellar coning (herniation) • cerebral herniation • flattened gyri • Microscopically • neuronal necrosis • edema is not evident in most cases E. Simko WCVM

  6. Polioencephalomalacia (PEM) • Thiamine-responsive PEM of ruminants • Lead poisoning in ruminants • Salt poisoning in pigs & occ. in rumin. • Hypoxia

  7. Response to injury - Brain edema Cytotoxic edema (cellular degeneration) Thiamine-responsive polioencephalomalacia in ruminants Etiology • Disturbance of thiamine production/absorption • concentrate ruminal pH change in flora • Bacterial thiaminase • [sulfur, sulfates, sulfides] in diet or water E. Simko WCVM

  8. Cytotoxic edema - Thiamine deficiency Pathogenesis • Thiamine interferes with glucose metabolism and Krebs cycle in CNS • ATP production • Na/K transport is impaired • Intacellular H2O (hydropic degeneration) • Cellular swelling (Cytototoxic edema) • Energy exhaustion • Intacranial pressure & blood perfusion • Ischemic necrosis E. Simko WCVM

  9. Cytotoxic edema - Thiamine deficiency Lesions • Brain swelling • (flattened gyri, cerebellar coning) • Yellow cortical discoloration • (autofluorescence under UV light) • Cortical liquefaction and cavitation Histology Laminar cortical necrosis E. Simko WCVM

  10. Cytotoxic edema - Thiamine deficiency Diagnosis • History • Response to thiamine • Gross and histologic lesions • Rule out the other causes of PEM E. Simko WCVM

  11. Cytotoxic edema - Thiamine deficiency Dietary thiamine deficiency in carnivores • Dog, cat, mink (Human – Wernicke’s encephalopathy) • Depend on exogenous source of vitamin • Pathogenesis: diet with thiaminase, sulfur preservatives or exposed to high temperature Lesions: Symmetrical necrosis of thalamic and mid-brain nuclei E. Simko WCVM

  12. Brain edema Lead poisoning Lesions: Source: Old batteries and paint Polioencephalomalacia similar to thiamine resp. Cattle Lead shotgun pellets PNS degeneration (Esophageal/crop dilation and impaction) Waterfowl E. Simko WCVM

  13. Direct endothelial injury vasogenic edema • Damaged metabolism cellular swelling • Energy exhaustion • Increased intracranial pressure • Failure of blood perfusion • Ischemic necrosis Brain edema - Lead poisoning Pathogenesis in cattle E. Simko WCVM

  14. Brain edema - Lead poisoning Diagnosis • Gross and histologic lesions • Lead particles in the rumen • Lead level in liver and kidney E. Simko WCVM

  15. Osmosis and semi-permeable cellular membrane Swelling Hypo Os Hypo Os Shrinkage Hyper Os Hyper Os

  16. Waterintoxication(IV H2O, behavioral, ADH) Brain edema Osmotic brain edema H2O H2O Edema Edema N N Dehydr. Dehydr. BRAIN PLASMA BRAIN PLASMA E. Simko WCVM

  17. Osmotic brain edema - Salt toxicity Water deprivation +/- high salt NaCl H2O t = 0 hr Edema Edema N N Cl- Na+ Cl- Na+ Cl- Cl- Dehydr. Na+ Cl- Na+ Cl- Dehydr. Na+ Na+ Na+ Na+ Na+ Na+ Cl- Cl- Cl- Na+ Cl- BRAIN PLASMA NormoNa HyperNa BRAIN PLASMA NormoOs HyperOs Dehydration Dehydration

  18. Osmotic brain edema - Salt toxicity Equilibration of CNS hyperNa t = > 36 hr Edema Edema N N Cl- Na+ AA Cl- Na+ Cl- Cl- Na+ Cl- Cl- Dehydr. Na+ AA Cl- Na+ Cl- Cl- Cl- Dehydr. Na+ Na+ Na+ Na+ Cl- Na+ Cl- Na+ Na+ Na+ Cl- PLASMA BRAIN PLASMA BRAIN NormoNa HyperNa HyperNa HyperNa HyperOs HyperOs HyperOs HyperOs Dehydration Dehydration Dehydration Dehydration

  19. Osmotic brain edema - Salt toxicity Water access t = > 36 hr H2O Edema Edema N N AA Cl- Na+ AA Na+ Cl- Na+ Cl- Cl- Cl- Dehydr. Dehydr. Na+ Na+ AA AA Cl- Cl- Na+ Na+ Na+ Cl- Na+ Cl- Na+ PLASMA PLASMA BRAIN BRAIN NormoNa HyperNa NormoNa NormoNa HyperOs HyperOs HyperOs NormalOs Dehydration Dehydration Edema Normal hydr.

  20. Osmotic brain edema - Salt toxicity Lesions • Brain swelling • Cerebrocortical necrosis (occ) Histology • Laminar cerebrocortical necrosis • Perivascular eosinophilic infiltrate (Po) E. Simko WCVM

  21. Osmotic brain edema - Salt toxicity Diagnosis • History • Gross and histologic lesions • Na level in the brain E. Simko WCVM

  22. Vasogenicbrain edema Vasogenic brain edema • The most common type of brain edema • Pathogenesis: damaged BBB • Examples: • Toxins • Inflammatory processes (H. somnus) E. Simko WCVM

  23. White matter Grey matter E. Simko WCVM

  24. Vasogenicbrain edema - Salt toxicity Toxin-induced Toxins • Shigella toxin type II (Edema disease) Po • Fibrinoid vasculitis • Epsilon toxin (C. perfringens D enterotoxemia) Ov • Symmetrical encephalomalacia • Fumonisin B1 (Fusarium momiliforme) Moldy corn • Equine leucoencephalomalacia E. Simko WCVM

  25. Response to injury - Necrosis Necrosis Trauma Thiamine deficiency Lead poisoning Salt poisoning Edema disease Clostridial eterotoxemia Equine leucoencephalomalacia Infarction

  26. Infarction

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