Path 2 - Neuro 6

drraythe's version from 2016-03-07 18:00

Trauma & Miscellaneous lesions

Question Answer
What is a concussion?Sudden, non-fatal blow to the head → loss of consciousness & reflex activity. (Sudden violent movement of CSF & blood)
Why is there a loss of consciousness in a concussion?There is a sudden but transient loss of consciousness in a concussion due to a transient anemia czd by a certain amount of blood being prematurely jarred from capillaries into larger vessels
CONCUSSION → mechanism of displacement & transformation of brain? Lesions? Prognosis?Shearing strains on neurons, axons, dendrites, synapses, blood vessels may be involved
Lesions: Chromatolysis >> irreversible damage
PROG: In mild cases, full recovery expected
Which is more severe-a concussion or a contusion?Contusion is more severe
What is a contusion?"A bruise" basically → applied force (blow) & brain displacement are more severe than in a concussion. The architecture of the nervous tissue is retained, but you will see hemorrhage (meningeal, perivascular (brain parenchyma) )
What are the 2 types of injuries associated w/ a contusion?(1) Focal-hemorrhage at the point of impact (coup)
(2) Diffuse-severe hemorrhage on the surface of the brain opposite to the point of impact (contrecoup)
What about the impact determines whether the ensuing contusion is of the coup or contrecoup type?The amount of energy dissipated at the site of direct impact determines whether the ensuing contusion is of the coupor contrecouptype
Impact from a small hard object → would this cz a coup or contrecoup?Energy tends to dissipate at the impact site → COUP!
Impact from a large object → would this cz a coup or contrecoup?Energy dissipated at the beginning or end of the head motion → less injury at the impact site → contrecoup contusion
Explain what is happening w/ the brain & what hits the head & the energy that happens from this in a COUP lesionThe BRAIN IS STATIONARY & the object that hit the head was MOVING. There is energy dissipation at the impact site & this makes a coup lesion at the point of impact
*Explain what is happening w/ the brain & what hits the head & the energy that happens from this in a CONTRECOUP lesionMoving head hits a stationary object (usually the ground). There will be a coup injury at the point of impact & then energy dissipation at the beginning or end of the head motion → contrecoup injury opposite the point of impact due to movement of the brain w/in the head
Is there coup, contrecoup, or both lesions when there is a blow to the occiput (very back of the head)The brain hits the posterior part of the head → then slides forward & backward several times → if the anterior part of the skull was smooth there would be no damage to the brain. However the petrous temporal ridge & orbital frontal skull are ridged & irregular, causing brain to be torn out as it moves across them causing a coup & contrecoup injury
Is there coup, contrecoup, or both lesions when there is a blow to the front of the head?There is only a large coup lesion since the posterior part of the skull is smooth (I think)
say 3 ways there can be Injury to the spinal cord due to intervertebral (IV) disc abnormalities(1) Partial or complete rupture of the Annulus Fibrosis (outer ring part)
(2) Bulging (w/o rupture) of the Annulus Fibrosis & Nucleus Pulposus into the vertebral canal
(3) Degeneration of the Annulus Fibrosis & Nucleus Pulposus → disc abnormalities
IV disk ABNORMALITIES: What are the 2 of the dz which can occur in dogs? What do both forms involve?(1) Hansen type I
(2) Hansen type II
Both involve degeneration of IV disks (mechanisms of degeneration & breed predisposition are different)
**Hansen Type I vs Hansen Type II disk deformities(I) Acute rupture, multiple disc involved, early degen, younger age, Chondroystrophoid breeds
(II) Gradual rupture, less disc involved, older age, all breeds
IV disk deformities → Hansen Type I → what is happening to the Annulus Fibrosis? Nucleus pulposis? How fast does this type of deformity occur? What happens to the spinal cord? How many disks are usually affected? What age is usually affected?Progressive degeneration of the Annulus Fibrosis & mineralization of the Nucleus Pulposus...this means there is acute rupture of annulus fibrosis, protrusion of nucleus pulposus into spinal canal, compression of the spinal cord, inflammation & nerve destruction & multiple diskscan be affected. This usually happens at an EARLY age (CSs by 3yo)
Chondrodystrophic breeds tend to get WHICH Hansen type disk dz? Give examples of chondrodystrophic breedsHANSEN TYPE 1!
American Cocker Spaniel
Basset hound
French & other bulldogs
Remember they will have SUDDEN onset & it will be VERY PAINFUL
IV disk deformities → Hansen Type II → what happens to the Annulus Fibrosis? What happens to the Nucleus Pulposus? How fast does this type of deformity occur? What happens to the spinal cord? How many disks are usually affected? What age is usually affected?Type II is a slower, more gradual degenerative process. In the A.F. you'll see small partial tears (nuclear material escapes into the annular area → bulging of the disc, w/ only occasional actual "escapes" of nuclear material outside the Annulus Fibrosis). There will be chronic bulging of Nucleus Pulposus into the spinal canal. BC of this, there will be compression of the spinal cord (no inflammation/nerve destruction like in type I). It doesn't involve many disks (that's type I that does) & bc its gradual onset, it affects older dogs (8 to 10 years of age)
Common sites for IV disk dz?Terminal thoracic & lumbar segments
Equine wobbles → aka? (A bunch of akas), what is this in general? What is the effect on the CNS?AKA: equine incoordination, equine ataxia, cervicospinal arthropathy. This is a locomotor disturbance in young horses. This problem czs slight nonprogressive injury to the spinal cord
**What are the 2 main possible etiopathogenesises of equine wobbles?(1) Cervical vertebral instability (vertebral deformities: malalignment & hypermobility, degeneration of the articular processes
(2) Cervical static stenosis (narrowing of cervical spinal canal) (STENOTIC myelopathy)
What is the pathogenesis of equine wobbles? Where is the usual site of lesions?PATHOGENESIS: relaxation of the intervertebral ligaments → ↑ mobility of the articulations → stretching & compression of the spinal cord. The USUAL SITES of lesions are: btwn the 3rd & 4th cervical vertebrae, may also extend from C2-C3 to the anterior thoracic vertebrae. CSs are accentuated if you try walking the animal in a tight circle, turning abruptly on a lead or forcing the head & neck into flex while backing
What are the CS of equine wobbles? What is the onset like? How are CSs accentuated?Insidious (slow) onset... signs 1st observed in the hind limbs (forelegs in some cases tho). You will see a drunken, weaving gait
What are the gross lesions of equine wobbles?May or may not be visible to the naked might see brownish-yellow foci of malacia (might be very small-make sure to fix SC for a day or 2 & slice super thin to detect)
What are the microscopic lesions of equine wobbles?Demyelination to the white matter ("moth-eaten" appearance) → microcavitations in areas of liquefactive necrosis, dorsal funiculi (anterior to 1°focus) ventral & ventrolateral funiculi (caudal to 1°focus) (A funiculus is a bundle of 1 or more nerve fascicles)
*Osseous metaplasia of the dura (Pachymeningitis ossificans) → what is happening here?Formation of bony plaques in the cranial or spinal dura (the plaques often contain marrow & may appear WHITE & RED)
Osseous metaplasia of the dura (pachymeningitis ossificans) → who does this usually occur in? What are the sequelae?Usually occurs in large breeds of dogs after maturity. The sequelae can be asymptomatic, or there can be pressure on the spinal cord & spinal nerve roots which leads to pain & gradual paresis
*Cholesteatosis (cholesteatoma) → what is this? What is this not? WHO gets this?Degeneration of the choroid plexus (plexus in the ventricles of the brain where cerebrospinal fluid (CSF) is produced). IT IS not a true neoplasm!!!! It occurs in OLD HORSES. GRANULOMATOUS INFLAMMATION w/ CHOLESTEROL CRYSTALS
What is the pathogenesis of a Cholesteatosis (cholesteatoma)? Where & what are the lesions?The pathogenesis is related to inflammatory changes. Lesions will be in the lateral ventricles & you will see cholesterol crystals, cholesterol clefts & fibrosis
Cholesteatosis (cholesteatoma) → what kinda inflammation is this, which is czd by what?Granulomatous inflammation induced by deposition of cholesterol
***CONTREcoup means damage where?Opposite side of the point of impact


Question Answer
***#1 MOST COMMON 1° tumor of dog + cat IS???MENINGIOMA
How do meningiomas grow? (Expansion or invasion?) What is the association they have w/ the-meninges (particular ones?) brain parenchyma? What are their characteristics?Growth by expansion, meaning they compress but seldom invade the brain parenchyma. They stay in the meninges in close association w/ the dura. They are well-circumscribed, encapsulated & have whorls & solid cords of spindle-shaped cells (uniform in size & shape)
What are the 2 kinds of glial cell tumors? Which is the most common?Astrocytoma & Oligodendroglioma. ASTROCYTOMA IS THE MOST COMMON
Glial cell tumors (astrocytoma & Oligodendroglioma) occur most often in who? How do they cz damage to the CNS?Occur most often in dogs (brachycephalic breeds). They usually act as SOLs (space occupying lesions) which may cz displacement of intracranial structures
Glial tumors → Astrocytoma: Where do these usually occur? In who?Usually occur in brain or spinal column in cats, dogs & cattle
Glial tumors → Astrocytoma: What is the GROSS APPEARANCE of these?Variable depending on malignancy & often go undetected (similar in color to normal brain tissue). They are solid, grayish-white, **poorly demarcated**
Glial tumors → Oligodendroglioma: What is the GROSS APPEARANCE of these?Well-demarcated, soft, cyst-like, grayish mass
**Glial tumors: Major diffs btwn astrocytomas & Oligodendroglioma?ASRO: COMMON, POORLY DEMARCATED
Embryonal tumors → how common is a medulloblastoma? What cells does this neoplasm arise from?RARE, arise from the undifferentiated cells found in neonatal life beneath the cerebellar pia matter which are thot to be precursors of the cerebellar cortex.
What is the gross appearance of a medulloblastoma? Where do they usually occur? What complications can they cz as a SOL?Well confined, soft, grayish or pinkish masses which often arise unilaterally in the cerebellar cortex or centrally in the vermis (cerebellum, cerebrum & pons). These often extending into or compressing the 4th ventricle → hydrocephalus
How do medulloblastoma cells appear?Cells are arranged radially around blood vessels or in true *rosettes*; mitotic figures are common (medulla stuck full of roses)
EMBRYONAL TUMORS → Ependymoma → what is the origin of this neoplasm? How common is this tumor? Who does it occur in?The origin is the ependymal cells (ventricles, spinal canal)...It is RARE, but occurs in dogs, cats, cattle, horses
How do ependymomas appear grossly? What problems can them cz?Large intraventricular masses (SOLs) which are well demarcated, gray & fleshy. They can cz cysts, necrosis, hemorrhage, hydrocephalus
Secondary (metastatic) neoplasms → what are the 2 main ways that metastatic tumors invade the CNS?(1) Hematogenous
(2) Direct invasion (such as w/ neoplasms of the sinuses & nasal mucosa)
Where do metastatic tumors have a predilection for in the CNS?The JUNCTION of the grey & white matter
****#1 most common tumor of DOG+CAT (in CNS)MENINGIOMA
****What does a meningioma grossly look like?WELL CIRCUMSCRIBED & encapsulated, w/ STREAMS & WHORLS
***Most common glial tumor?Astrocytoma