Session 18,19 - Neurology II + III Flashcards by Raegan Chambers

What are the most common reasons for hemorrhage/edema?

Trauma + Vascular accidents

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What about the color of the hemorrhage tells you about it’s age?

Red/black = early
Golden-brown = Late
Pale, shrunken scar = healed, very old

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What is one of the most dangerous types of hematomas? Why?

Sub-dural hematomas

Delayed, fatal manifestation of what seem like minor injuries

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Term: Concussion

Head injury leading to loss of consciousness without evidence of injury

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Term: Contusion

Head injury leading to hemorrhage
+/- tearing of brain parenchyma
+/- Skull fracture

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Why does coupe + contra coupe injuries occur?

Brain is encased in skull but is not attached to it. When a strong force occurs the brain will rattle back and forth. Causing injury on both sides.

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What can cause hematomyelia?

Disc herniation, or another form of trauma

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Term: Hematomyelia

Ascending and/or descending dissecting hemorrhage that extends along spinal cord from a point of grey mater arterial trauma

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How does Hematomyelia present?

Ascending or descending paralysis and sensory deficits

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How long after injury to the spinal cord do you start to see symptoms?

12 to 24 hours

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When is a hematomyelia most likely life threatening?

When they occur at the brainstem or 5th cervical cord segment

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Why is the 5th cervical cord segment most dangerous?

Phrenic nerve is present

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How do hematomyelias appear grossly?

Tracts of myelomalacia + hemorrhage WITHIN the cord

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What does the phrenic cord supply?

Diaphragm

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What are three common reasons for infarction within the cerebrum?

Vasculitis + Thrombosis + Embolism

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What are the results of cerebral infarction?

Necrosis + Hemorrhage + Edema

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What kind of necrosis occurs with cerebral infarction?

Liquefactive

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Term: Fibrocartilaginous emboli

Emboli made from degenerative intervertebral disc material

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How do fibrocartilaginous emboli cause an infarction in the spinal cord?

Material is extruded into SC blood vessels

Travels to parenchyma of SC

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What does intervertebral disc disease look like grossly?

Nucleus pulposis will have chalky white areas

These are areas of degeneration + mineralization

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What animals have a predisposition to CNS tumors?

Brachycephalics

Older dogs

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What type of CNS tumor is most common in Brachycephalic dogs?

Gliomas

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What are the common clinical signs of CNS tumors?

Seizures + Depression + Temperament changes + Propulsive gait + Blindness

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Term: Neuroglia

Macroglia + Microglia

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Term: Macroglia

Astrocytes + Oligodendrocytes

What are the two histologic Astrocyte types?

Fibrous + Protoplasmic

Where are fibrous astrocytes normally found?

White matter

What is the appearance of fibrous astrocytes?

Slender processes

What are fibrous astrocytes most commonly like?

Type 2

Where are protoplasmic astrocytes most commonly found?

Grey matter

What is the appearance of protoplasmic astrocytes?

Large with small number of short processes

What are protoplasmic astrocytes most similar to?

Type 1

Term: Gemistocytes

Astrocytes that respond to injury by increasing their cytoplasm Can become multinucleated

Term: Alzheimer Type 2 astrocytes

Cluster of astrocytic nuclei that are swollen and clear | Chromatin peripherally dispersed

What are alzheimer type 2 astrocytes most commonly associated with?

Hepatic + Renal encephalopathy

How do oligodendrocytes act in the gray matter?

Satellite cells

How do oligodendrocytes act in white matter?

Neuroglia, most numerous type

What is the primary function of oligodendrocytes?

Form myelin

CNS myelin forming cells

Oligodendrocyte

PNS myelin forming cells

Schwann cell

What two things does myelin do to the nerve?

Increase electrical resistance -- and -- Lowers capacitance

What is myelin made of?

78 to 80% lipids | PLP + MBP

What type of cholesterol is used in myelin formation?

Cerebrosides

What is PLP?

Proteolipid protein

What is MBP?

Myelin basic protein

What is the function of microglia?

Phagocytosis in the brain | aka Macrophages

What are the two places from which macrophages can come from that aid the brain in phagocytosis?

Microglia -- or -- Blood macrophages

What are all forms of glial tumors?

Malignant

What are astroglial tumors called?

Astrocytoma

What animals are predisposed to getting astrocytomas?

Aged animals | Brachycephalic breeds

What is the marginal appearance of astrocytomas?

Indistinct margins

Where are astrocytomas most commonly found in the brain?

Cerebrum | Temporal lobes

With astrocytomas, what are the most common gross features seen?

Swelling around the mass + Secondary effects

What are the three tumor consistencies that can occur with astrocytomas?

Fibrillary Protoplasmic Gemistocytic

What do fibrillary astrocytomas look like?

Firm

What do protoplasmic astrocytomas look like?

Soft or gelatinous

What do gemistocytic astrocytomas look like?

Softer

What is the histiological appearance of diffuse astrocytomas?

Well-differentiated Sheets of brightly eosinophilic astrocytic cells with prominent processes Atypical nuclear features

What is the histrological appearance of diffuse astrocytomas?

``` Nuclear variability Mitotic figures Dense, hyperchormatic nuclei Vascular proliferation within the mass Multinucleated cells ```

What dogs are predisposed to oligodendorgial tumors?

Mature, older dogs | Males more commonly then females

Where is the most common location of oligodendroglial tumors?

Frontal lobe

What is the gross appearance of oligodendroglial tumors?

Pink to gray Soft to gelatinous Central cysts can occur in large masses

What are the histological features of an oligodendroglial tumor?

``` Fried egg appearance Small round cells in a sheet pattern Weakly staining cytoplasm Sharp cell margins Some produce mucin ```

What are the two most common neuronal tumors?

Neuroblastoma -- and -- Primitive Neuroectodermal Tumor (PNET)

Term: Neuroblastoma

Primitive neuroepithelial cells that differentiate to neuroblasts

What do neuroblastomas look similar to?

Oligodendrogliomas

Term: PNET

Primitive tumors of any cell derivation

Term: Medulloblastoma

Undifferentiated cells of the neural tube

Where does medulloblastoma most commonly occur?

Cerebellum of young animals | In the external germinal cell layer

What does a medulloblastoma look like grossly?

Grey masses Commonly in the vermis +/- secondary hydrocephalus from obstruction

What is the histological appearance of a medulloblastoma?

Uniform, densely packed cells Sub-pial extension Elongated nuclei

What is the cellular arrangement in medulloblastomas?

Homer-wright rosettes

What is the most common intercranial brain tumor in cats?

Meningioma

Where do meningiomas most commonly arise from?

Arachnoid

Why can you get intraventricular meningiomas?

Pia mater is present in the choroid plexus

What type of neoplasm is a meningioma?

Benign

What is the gross appearance of a meningiomas?

Firm to rubbery Lobular to papillary Gray to pink Tend to peel out of area since they do not infiltrate other tissues

What are two important gross findings that can occur with meningiomas?

Hyperostosis -- and -- Compression below the tumor

Term: Hyperostosis

bone reaction to tumor

What is a differential that needs to be taken into consideration with meningiomas? Why?

Bacterial meningitis | Elevation of neutrophils present in CSF due to necrosis of tissues

What is the histologic appearance of meningiomas?

Can be mesenchymal, epithelial, or mixed Nest, laminated whorls, or streaming patterns Mineral commonly seen

Term: Ependyomas

Derived from ependymal epithelial cells that line ventricles of central canal of SC

What animal are choroid plexus tumors most commonly reported?

Dogs ( can occur in horses and cow though)

What is the most common location of choroid plexus tumors?

4th ventricle

What are the most common clinical signs of choroid plexus tumors

Vomiting + Positional nystagmus + Head tilt + Spastic tetraparesis

What three tumor types can occur in the choroid plexus?

Papilloma + Adenoma + Carcinoma

What are the gross features of a choroid plexus tumor?

Red/Grey to tan Nodular Malignant - infiltration of surrounding tissues will occur Hydrocephalus - if obstruction occurs

What is the histologic appearance of choroid plexus tumors?

Vascular papillary projections lined by cells

What cell type is seen in a choroid plexus papilloma?

Cubodial to columnar cells

What cell type is seen in a choroid plexus adenoma?

Dual layers of cubodial cells

What form of lymphosarcoma is primary in the brain?

CNS B cell lymphoma

What type of tumor is seen with B cell lymphoma in the CNS?

Reticulosis

What is the most common cancer in canines to metastasize into the brain?

Mammary

Term: Schwannoma

Benign tumor of a schwann cell

Term: Neruofibroma

Tumor is of schwann cell + perineural cell origin

What are the maglignant verisons of a schawannoma and neurofibroma called?

Malignant schwannoma -- and -- Peripheral nerve sheath tumor

What dogs tend to be predisposed to hmangiopericytomas?

Middle aged to older dogs

What is the general behavior of a hemangiopericytoma?

Arise in subcutis | Around joints of legs

What is the gross appearance of a hemangiopericytoma?

Very large Central necrosis Slimy to mucoid material on cut section

What is the histologic appearance of a hemangiopericytoma?

Perivascular whorls of fusiform cells Also in bundle or storiform pattern High degree of pleomorphism

What is a common problem with removal of hemangiopericytomas?

If you do not excise completely the tumor that comes back tends to be more malignant then the one before it

Term: Neurofibromatosis

Single or multiple neurofibromas + schwannomas | at multiple sites

What are the four places that neurofibromatosis tends to occur?

Heart + Branchial plexus + Mediastinum + Intercostal nerves

What animal tends to get neurofibromatosis?

Cattle