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34 Cards in this Set
- Front
- Back
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What are 3 causes of increased intracranial pressure?
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space occupying mass (tumor, abscess, hematoma)
edema or inflammation ↑ volume of CSF (hydrocephalus) |
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What is a possible result of a focal expansile process in the brain?
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brain displacement & herniation beneath membranous partitions of dura mater (falx cerebri, tentorium cerebelli, foramen magnum)
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What are some causes of brain edema?
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anoxia, hypoxia, hypoglycemia, vessel injury d/t tumor, toxins, inflammation, trauma, toxins
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What is the gross lesion associated w/ brain edema?
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laminar cortical necrosis: linear paleness at junction of white & gray matter
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What are the characteristics of normal CSF & CSF flow?
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-clear, colorless ultrafiltrate of blood plasma
-produced by choroid plexus of lateral, 3rd, & 4th ventricles -daily production is 3-5x volume of ventricular cavities: produced against a pressure gradient -content: glucose: ~80% level in blood, protein: MUCH less than in blood (measured in mg/dl vs. g/dl in blood), few cells flow is unidirectional: ventricular system --> subarachnoid space --> venous sinuses |
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What is the pathogenesis of hydrocephalus?
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obstruction of mesencephalic aqueduct --> CSF production continues against pressure gradient --> dilation of lateral ventricles
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What are some causes of acquired hydrocephalus?
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-brain stem tumor compresses mesencephalic aqueduct
-inflammation --> destruction of aqueduct -inflammatory exudates occlude lateral apertures, obstructing CSF outflow (ex. FIP, Cryptococcus) -failure of CSF reabsorption: uncommon |
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What are some causes of congenital hydrocephalus & in what type of dogs is it most common?
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-most common in toy breed dogs
-cause often unknown (viral infection of pregnant animal can cause hydrocephalus in fetus) -development of advanced hydrocephalus before skull bones have fused & ossified --> outward protrusion of skull (dome shaped) |
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What is the pathogenesis of cerebellar hypoplasia associated w/ feline panleukopenia?
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unvaccinated, pregnant queen infected --> virus crosses placenta & infects fetus --> destroys mitotically active external germinal layer of cerebellum --> failure of cerebellar development (hypoplasia) --> small cerebellum at birth & lack of coordinated movement
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What manifestation of FIP produces nervous system lesions & where is the inflammation found?
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weak immune response: dry form: granulomatous meningoencephalitis
inflammation along flow path of CSF |
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pug encephalitis
a. signalment b. signs c. gross |
a. juvenile to young pugs, maltese, yorkies
b. acute onset of depression, circling, seizures, ataxia, head tilt, etc. lasting 1-8 wks c. inflammation of meninges & cerebral white AND gray matter --> extensive necrosis --> residual cavitations |
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Toxoplasma gondii
a. gross b. microscopic c. ddx d. pathogenesis |
a. none to areas of yellow tan discoloration primarily in gray matter
b. nonsuppurative meningoencephalitis in gray matter c. Neospora caninum d. most infections in intermediate hosts are inapparent: tissue cyst (psuedocysts) form in brain: may remain latent for life of animal -activation of pseudocysts & clinical dz may be assoc. w/ immunosuppressive therapies or systemic dz |
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What is a concussion?
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transient neurological dysfunction d/t head injury w/ no demonstrable brain lesion
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What is a contusion & what are coup & contrecoup lesions?
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head trauma --> meningeal & possibly perivascular hemorrhage in brain tissue
coup lesion: hemorrhage adjacent to injury site contrecoup lesion: hemorrhage opposite injury site |
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What can result from brain stem hemorrhage & necrosis?
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causes injury to ascending reticular activating system --> disturbance in consciousness (coma)
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Where in the brain are hematomas most common?
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subarachnoid
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What lesions are produced by explosive extrusive of IVD material?
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hemorrhage, edema, necrosis of spinal cord centered on gray matter --> sudden onset of neurologic dysfunction (paraplegia)
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What lesions are produced by gradual protrusion of IVD material?
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gradual demyelination & axonal degeneration in spinal cord white matter --> progressive onset of neurologic dysfunction
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What affects can occur on rest of spinal cord from IVD extrusion?
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hemorrhagic necrosis of spinal cord --> ascending & descending hemorrhagic myelomalacia (necrosis)
central zone of hemorrhagic necrosis extends cranially &/or caudally from initial injury site (does not always occur, but is life threatening) |
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What are the gross & microscopic lesions associated w/ IVD protrusion?
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causes pressure on spinal cord
gross: normal or compression at point of contact w/ protruded disk microscopic: varying degress of demyelination, axonal degeneration & gitter cells filled w/ ingested myelin & axonal debris |
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Wobblers
a. microscopic lesions b. dogs c. horses |
a. axonal degeneration & demyelination
b. large breeds, usually C5-C7, progressive pelvic limb ataxia c. rapidly growing large breeds, usually at C3-C4, but also at C4-C7, ddx: equine degenerative myelopathy: dz of young horses w/ similar microscopic lesions in spinal cord but NORMAL vertebrae |
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hepatic encephalopathy
a. pathogenesis b. microscopic lesions |
a. PSS or chronic liver dz --> ↑ blood ammonia d/t failure of conversion to urea in liver
b. vacuolation of white matter (may be mild) NO gross lesions |
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lysosomal storage diseases
a. pathogenesis b. causes c. microscopic lesions |
a. deficiency of lysosomal enzyme or lack of activator of enzyme --> lysosomal accumulation of complex macromolecules normally degraded by lysosomes
b. usually inherited, also toxic plants (cattle) c. foamy appearance of neuronal cytoplasm (usually cannot see cytoplasm) |
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Why is brain very sensitive to hypoxia & ischemia? Which cells are most sensitive?
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highest energy demands in body
limited collateral circulation neurons most sensitive, esp. in deep laminae of cerebral cortex > oligodendrocytes > astrocytes > microglia |
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What gross lesion is associated w/ hypoxia & ischemia of the brain?
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laminar cortical necrosis: locally extensive to diffuse necrosis most notable at junction of white & gray matter
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feline ischemic encephalopathy
a. proposed etiology b. signs c. gross lesions |
a. Cuterebra larval migration
b. acute onset of depression, ataxia, circling in adult cats c. brain appears asymmetrical d/t infarction & necrosis of up to 75% of 1 cerebral hemisphere or 1 side of cerebellum (usually in area supplied by middle cerebral artery) |
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hypoglycemic neurologic dz
a. signs b. #1 cause in dogs c. microscopic lesions |
a. weakness, transient blindness, abnormal behavior, seizures
b. beta cell tumor (insulinoma) c. neuronal degeneration in middle & deep laminae of cerebral cortex |
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fibrocartilaginous embolic myelopathy
a. signalment b. signs c. gross lesions d. dx |
a. non-chondrodystrophic dog breeds
b. acute onset of lameness of 1 or more limbs --> paralysis in a matter of hours (BAR, no pain) c. spinal cord infarction, usually caudal to T3: may appear similar to cord injured by extruded disk but w/o evidence of IVDD (may involve gray & white matter) d. find 1 or more light gray to purple emboli in vessels near site of infarction |
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cerebellar cortical abiotriophy
a. pathogenesis b. signalment c. signs d. microscopic lesions e. gross lesions |
a. premature degeneration of Purkinje cells & small neurons in internal granular layer
b. dogs a few weeks or months of age; adult onset in Am Staffs c. ataxia, dysmetria, head tremor, broad based stance d. purkinje cell loss in cerebellar folia e. none to small cerebellum |
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degenerative myelopathy of old animals
a. signalment b. signs c. microscopic lesions |
a. most common in GSDs, also Welsh Corgis, Boxers, other large breeds, occ. cats; dogs usually > 5 yo; genetic predisposition
b. insidious onset of progressive paraparesis, ataxia, & muscle atrophy of pelvic limbs d. axonal degeneration, demyelination, gitter cells in all segments of spinal cord |
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What are the 3 most common primary neoplasms in the CNS?
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meningioma
astrocytoma oligodendroglioma |
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What is the most common location of LSA in the nervous system?
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most found in vertebral canal OUTSIDE dura mater (vs. meningioma, on surface of dura)
most are single masses that compress & destroy brain or spinal cord parenchyma |
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What are some secondary tumors of the CNS?
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LSA, HSA, carcinomas, malignant melanoma
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Schwannoma or benign peripheral nerve sheath tumor
a. signalment b. signs c. gross lesions d. most common location |
a. dogs (usually > 8 yo)
b. often unilateral paresis c. thickening of a single nerve or nerve root or fusion of adj. nerves by firm, grayish cylindrical mass d. middle to distal cervical &/or cranial thoracic nerve roots |
