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34 Cards in this Set

  • Front
  • Back
What are 3 causes of increased intracranial pressure?
space occupying mass (tumor, abscess, hematoma)

edema or inflammation

↑ volume of CSF (hydrocephalus)
What is a possible result of a focal expansile process in the brain?
brain displacement & herniation beneath membranous partitions of dura mater (falx cerebri, tentorium cerebelli, foramen magnum)
What are some causes of brain edema?
anoxia, hypoxia, hypoglycemia, vessel injury d/t tumor, toxins, inflammation, trauma, toxins
What is the gross lesion associated w/ brain edema?
laminar cortical necrosis: linear paleness at junction of white & gray matter
What are the characteristics of normal CSF & CSF flow?
-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
What is the pathogenesis of hydrocephalus?
obstruction of mesencephalic aqueduct --> CSF production continues against pressure gradient --> dilation of lateral ventricles
What are some causes of acquired hydrocephalus?
-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
What are some causes of congenital hydrocephalus & in what type of dogs is it most common?
-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)
What is the pathogenesis of cerebellar hypoplasia associated w/ feline panleukopenia?
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
What manifestation of FIP produces nervous system lesions & where is the inflammation found?
weak immune response: dry form: granulomatous meningoencephalitis

inflammation along flow path of CSF
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
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
What is a concussion?
transient neurological dysfunction d/t head injury w/ no demonstrable brain lesion
What is a contusion & what are coup & contrecoup lesions?
head trauma --> meningeal & possibly perivascular hemorrhage in brain tissue

coup lesion: hemorrhage adjacent to injury site

contrecoup lesion: hemorrhage opposite injury site
What can result from brain stem hemorrhage & necrosis?
causes injury to ascending reticular activating system --> disturbance in consciousness (coma)
Where in the brain are hematomas most common?
What lesions are produced by explosive extrusive of IVD material?
hemorrhage, edema, necrosis of spinal cord centered on gray matter --> sudden onset of neurologic dysfunction (paraplegia)
What lesions are produced by gradual protrusion of IVD material?
gradual demyelination & axonal degeneration in spinal cord white matter --> progressive onset of neurologic dysfunction
What affects can occur on rest of spinal cord from IVD extrusion?
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)
What are the gross & microscopic lesions associated w/ IVD protrusion?
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

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
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
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)
Why is brain very sensitive to hypoxia & ischemia? Which cells are most sensitive?
highest energy demands in body

limited collateral circulation

neurons most sensitive, esp. in deep laminae of cerebral cortex > oligodendrocytes > astrocytes > microglia
What gross lesion is associated w/ hypoxia & ischemia of the brain?
laminar cortical necrosis: locally extensive to diffuse necrosis most notable at junction of white & gray matter
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)
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
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
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
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
What are the 3 most common primary neoplasms in the CNS?
What is the most common location of LSA in the nervous system?
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
What are some secondary tumors of the CNS?
LSA, HSA, carcinomas, malignant melanoma
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