Path 2 - Neuro 3

drraythe's version from 2016-03-07 17:31

Necrosis (malacia)

Question Answer
What is malacia?Literally, "softening". It is associated w/ encephalitis, trauma, anoxia, etc & indicates necrosis of tissue in the CNS
What czs vascular necrosis of the CNS?A thromboembolism! (Thrombosis, embolism, vasculitis, ruptured aneurysms)
What are 2 czs of hypoxia-induced necrosis of the CNS?Hypoglycemia, anesthesia
Name 7 toxins (3 groups) of toxins which can cz malacia/necrosis(1) Yellow star thistle
(2-6) Pb, Hg, NaCl, Se, Sulfur
(7) Mycotoxicosis (moldy corn)
Yellow star thistle czs what kinda necrosis of the NS & affects who?Nigropallidal malacia in horses
Pb (lead) czs what kinda necrosis in who?Laminar necrosis; horse/dog (poliomyelomalacia) (cattle get CCN)
Se (selenium) czs what kinda necrosis in who?Poliomyelomalacia; pig
**NaCl (sodium chloride, table salt) toxicity czs what kinda necrosis in who?Laminar necrosis + eosinophilic ME (meningoencephalitis); pig (poliomyelomalacia) (Pigs are allergic to salt & allergic to watching CNN)
Mycotoxicosis (Moldy corn) czs which type of necrosis?Leukoencephalomalacia
*What is leukomalacia?White matter necrosis
*What is poliomalacia?Gray matter necrosis
*What is encephalomalacia?Brain as a whole necrosis
*What is myelomalacia?Spinal cord necrosis
What is encephalomyelomalacia?Brain & spinal cord necrosis
Czs of necrosis: "turning sickness" what czs this?Cerebral theileriosis (parasite) (TURN the page on the theliero textbook)
Which 2 parasites can cz CNS necrosis?Theileria & babesia
Which bacteria can cz CNS necrosis?Clostridium perfringens type D
Equine leukoencephalomalacia is czd by what?Moldy corn-(mycotoxicosis)
Nutritional → which Vitamin deficiencies can cz necrosis? (3)A, B1, E
Nutritional → which mineral deficiency can cz necrosis? (In who?)Cu, in sheep
Nutritional → a diet high in ___ can cz necrosis as wellSulfur (sulfur will rot your brain)
What are the 2 main types of lesions (patterns) which CNS necrosis can manifest as?FOCAL & LAMNIAR (there was also diffuse mentioned but not in outline)
*FOCAL lesions → explain this pattern of lesions. What are the 4 situations where you see a focal pattern of necrosis?Necrosis in selective areas in the CNS. Usually due to a specific toxin/nutritional def.
(1) FSE (Focal Symmetrical Encephalomalacia) in sheep (Clostridium perfringens D)
(2) Eequine Leukoencephalomalacia (moldy corn dz)
(3) Equine Nigropallidal Encephalomalacia (Yellow star thistle toxicity)
(4) Avian Encephalomalacia (Hypovitaminosis E)
(D CORN is STAR E...lets FOCUS on it)
FSE (focal symmetrical encephalomalacia) in sheep (Clostridium perfringens D) → which pattern of necrosis?Focal
Equine leukoencephalomalacia → which pattern of necrosis?Focal (white corn makes focal spots of rot, spot for each kernel)
Equine nigropallidal encephalomalacia (yellow star thistle toxicity) → which pattern of necrosis?Focal
Avian encephalomalacia (hypovitaminosis E) → which pattern of necrosis?Focal
Laminar pattern (laminar cortical necrosis) → how does this happen (in general)This pattern occurs due to selective susceptibility of various cells in the CNS to hypoxia
Laminar pattern of necrosis occurs bc of different degrees of susceptibility of different cells in the nervous system. Put the 4 types of cells in order from most to least susceptibleNeurons > oligodendroglia > astrocytes > microglia (NOAM)
3 examples of czs of a laminar pattern of necrosis (HYPOXIA SUSCEPTIBILITY) & WHO is affected by each cz?(1) Thiamine depletion/deficiency (ruminants/ cats)
(2) Salt poisoning (pigs)
(3) Lead poisoning (cattle)
Vit B1 deficiency czs what?Polioencephalomalacia (B for Black as in grey matter)
Vit E deficiency czs what?Avian encephalomalacia (brain necrosis-remember the necropsy lab?)
Vit A deficiency czs what?Blindness
Cu deficiency czs what? (In who?)Bilateral CCN (Cerebrocortical necrosis) + axonal degeneration; lambs/kids (Cu Ccn sheep)
*Yellow star thistle czs what in who?Nigropallidal malacia; horse (BLACK & YELLOW HORSES)
*Pb poisoning czs what in who?Laminar necrosis; cattle/horse/dog
*Se poisoning czs what in who?Poliomyelomalacia; pig (a pig w/ a selenium cast bc it had polio)
*NaCl poisoning czs what in who?Laminar necrosis + eosinophilic ME; Pig
**Moldy corn has what toxin, which czs what in who?Fumonisin B1, mycotoxicosis (focal necrosis), Horse
****Know the vascular, hypoxic, toxin, infectious & nutritional czs of necrosis (& possible type of necrosis they cz)Toxins are:
Yellow star thistle (nigropallidal malacia)
Lead, Na, Cl, Se (Poliomyelomalacia)
Moldy corn (Leukoencephalomalacia)
****Clostridium perfringens D czs what in who?Focal Symmetrical Encephalomalacia (FSE) in SHEEP
****LAMINAR CORTICAL NECROSIS → aka (2 aka) & this occurs why?Aka “cerebrocortical necrosis” (CCN), “polioencephalomalacia” – specific layer. Softening of the cerebrocortical grey matter in a laminar (layered) pattern based on susceptibility of cells to hypoxia
****Lead poisoning-chronic (cattle) → CCN, POLIO, OR BOTH?“Cerebrocortical necrosis” (CCN), (You're gonna get a lead bullet, C?)
****Salt poisoning (pigs) → CCN, POLIO, OR BOTH?POLIO (black Himalayan salt)
****Selenium poisoning-acute (pig) → CCN, POLIO, OR BOTH?BILATERAL POLIO (selenium casts on BOTH legs bc pig got polio)
****Thiamine deplete/def (Rum/Cat) → CCN, POLIO, OR BOTH?BOTH (two thighs-both things)
****Cell Susceptibility to Laminar cortical necrosis (most to least)"NOAM" Neurons > Oligodendrocytes > Astrocytes > Microglia

Circulatory disturbances

Question Answer
Hypoxia-ischemia → what is the result of global (generalized) ischemia on the NS? Regional (localized)?Global: ischemic encephalopathy. Regional: infarction
4 factors affecting cerebral blood flow(1) Systemic blood pressure
(2) Vascular patency
(3) Intracranial pressure
(4) Capacity for autoregulation
Ischemia is a lack of what 2 things, which is DEVASTATING to the brain (& why so devastating)Its hypoxia & hypoglycemia, which is DEVASTATING bc it has the highest energy demands
****What is the order of sensitivity of cells/brain elements to hypoxia/ischemia?Neurons > Oligodendrocytes > Astrocytes > Microglia > Fibrovascular elements
In myelinated fibers, which is more sensitive to hypoxia-ischemia...the axon or the myelin sheath?Axon more sensitive
What is going on in reperfusion injury? What potentiates this type of dmg?If there is ischemic dmg & then blood flow is restored, interactions btwn blood constituents & the dmgd tissue lead to further insult. Things that potentiate this problem are leukocyte products, free radicals, Ca++ (high levels of Ca shut down mitochondria which leads to necrosis) & excitatory neurotransmitters (L-glutamate can produce neuronal necrosis)
Hypoxia-ischemia & related disorders → patterns of excitotoxin-mediated neuronal injury: Acute dmg. Explain what happens hereEntry of Ca2+and Na+ (which are followed by Cl-and water) → leads to osmotic cell swelling & lysis
Hypoxia-ischemia & related disorders → patterns of excitotoxin-mediated neuronal injury: chronic cell injury. Explain what happens hereElevated levels of intracellular calcium → activation of Ca2+-dependent protease, phospholipase & free radicals
Hypoxia-ischemia, hypoglycemia, energy depletion → (explain steps to how this leads to death)Glutamate release is ↑ → neurotoxicity → neuronal death
Hypoxia-ischemia & related disorders ischemia → explain how this gets to breakdown of cell structureFailure of cellular energy sources (e.g. ATP) → stimulates anaerobic glycolysis → disruption of ion homeostasis → breakdown of cell structure
In summary, what are the 4 major mechanisms of Hypoxia-ischemia related disorders?(1) Lactic acidosis
(2) Ca+ influx
(3) Oxygen-free radicals
(4) Excitotoxins
In summary, what are the 4 major responses to hypoxia-ischemia related disorders?(1) Swelling of perineuronal astrocyte foot processes
(2) Neuronal contracture
(3) Cytoplasmic eosinophilia
(4) Nuclear Pyknosis, Karyorrhexis, Karyolysis
Hypoxia-ischemia examples → 3 horse-related problems pertaining to this?(1) Neonatal maladjustment syndrome in foals
(2) Anesthesia-related syndromes in horses ("post-anesthetic syndrome")
(3) Encephalomalacia following intracarotid injxn in horses
Hypoxia-ischemia examples → example in dogs?Fibrocartilaginous embolic myelopathy (FCEM) in dogs
Hypoxia-ischemia examples → 2 examples in cats?(1) Feline ischemic encephalopathy (Cuterebra)
(2) Traumatic feline ischemic myelopathy
Neonatal maladjustment syndrome (NMS) in foals is aka & is bc of what?Aka “barker & wander”, “dummy”, “convulsive” foals. Happens due to hypoxia-ischemia (dystocia → cerebral hypoxia)
Hypoxia-ischemia → anesthesia-related syndromes → in horses, what are the 2 Dzs of this? What is happening to cz these Dzs?Post-anesthetic hemorrhagic myelopathy & post-anesthetic cerebral necrosis. It occurs when there is intubation for inhalant gases DEVOID OF OXYGEN!
_________ minutes of hypoxia is lethal to neurons>= 5 min
What are neuronal changes associated w/ hypoxia?Intense cytoplasmic eosinophilia, pyknosis (irreversible condensation of chromatin), karyolysis (the complete dissolution of the chromatin of a dying cell due to the enzymatic degradation by endonucleases)
Hypoxia-ischemia → encephalomalacia following intracarotid injxn in horses → what happens here? What are the resulting CS & what are the lesions/quality of lesions in the brain from this?Accidentally injecting medication into the carotid artery instead of into a vein → you will see headshaking, kicking, collapse, coma. The lesions you will see will be vascular endothelial injury, thrombosis, hemorrhage, infarction. The quality of the lesions will be asymmetric, miliary: on the side of injxn due to laminar flow of blood in the cerebral arterial circle
Way you can tell by the brain lesions that the dmg was from a carotid injxn?Lesions are ON THE SIDE OF THE INJXN due to the LAMINAR BLOOD FLOW
Hypoglycemia is a major cz of Hypoxia-ischemia dmg in the brain. What are some reasons you'd see hypoglycemia?Fasting
Addison’s Dz (↓ gluconeogenesis)
Severe hepatic & renal dz
Glycogen storage dzs
Pancreatic β-cell tumors
Fibrocartilaginous embolic myelopathy (FCEM) in dogs → what is happening here? CS?Degeneration of intervertebral discs >> prolapse >> hemorrhage, embolism, infarction (myelomalacia)...this czs lameness, paralysis (limbs)
Feline ischemic encephalopathy → what is the proposed causative agent, what is happening?Possibly czd by cuterebra (bot fly larvae), migrating parasite >> hemorrhage >> vasospasm >> cerebral ischemia
Traumatic feline ischemic myelopathy → what is happening here? What ISNT happening?Abdominal injury >> acute pelvic limb paralysis... this is bc the SC got a contusion (bruise) >> vasospasm or thrombosis of lumbar arteries. no vertebral column injuries involved!
What is hematomyelia?Blood in the central canal of the spinal cord
What are the sites where hemorrhage can occur in the CNS?(1) Epidural, subdural, Leptomeningeal spaces (Lept=the pia mater & the arachnoid considered together as investing the brain & spinal cord)
(2) Brain parenchyma
(3) Central canal of the spinal cord (hematomyelia)
What is hemorrhagic diatheses?Unusual susceptibility to bleeding (hemorrhage) mostly due to hypocoagulability
Where can ICH (infectious canine hepatitis) cz CNS bleeding?Midbrain & medulla (Herpes in the middle btwn you & me)
Focal symmetrical encephalomalacia (FSE) in sheep can cz bleeding where?Bilaterally symmetrical in internal capsule, thalamus & pons
Thiamine deficiency in cats leads to hemorrhage where?Inferior colliculi
Which parasite in cattle can cz CNS bleeding?Cerebral theileriosis in cattle
Which parasites in dogs can cz CNS bleeding?Canine Toxoplasmosis & canine cerebral babesiosis
What kinda poisoning in dogs can cz CNS bleeding?Diamidine poisoning
What are 4 different consequences which can happen bc of hemorrhage in the CNS?(1) No effect
(2) SOL (SPACE OCCUPYING LESION) >> ↑ intracranial pressure
(3) Blood clots → obstruction to the flow of CSF w/in ventricles, ducts & the subarachnoid space >> hydrocephalus
(4) Organized thrombi & blood clots may be epileptogenic
****EDEMA LEADS TO WHAT MAJOR PROBLEM?↑ INTRACRANIAL PRESSURE (from inflammation, hypoxia, ischemia, toxins)