PATH1 Neuropathology

- trauma

- vascular events

what causes CNS hemorrhage and edema

- ataxia

- behavioral changes

- seizures

- head presssing

- circling (toward lesion)

- blindness

common clinical signs in cerebrum/forebrain injury (central signs)

- ataxia

- hypermetria

- hypertonicity

- head tilt

- circling

- nystagmus

- tremors

- cranial nerve deficits

common clinical signs in midbrain/cerebellum/brainstem injury

- paralysis

- weakness

- spasticity

common clinical signs with spinal cord injury

coup

injury on the same side as impact

contracoup

injury on the opposite side of impact

concussion

head injury leading to loss of consciousness without gross evidence of injury

contusion

head injury that results in hemorrhage, +/- tearing of brain parenchyma, +/- skull fracture

fracture

- happens to skull or vertebrae

- when this happens, bone can act as foreign body or mechanism for laceration of neurological tissue it surrounds

- can have effects as space occupying lesion

- increased intracranial pressure

- compression

- +/- herniation (cerebellum most common)

- can be delayed

hematoma

- dura mater

- pia mater

- arachnoid mater

3 layers of meninges

epidural hematoma

hematoma outside of the meninges

subdural hematoma

hematoma inside the meninges

intracerebral hematoma

hematoma within the brain

cerebral herniation

cerebral coning

- nucleus pulposus

- annulus fibrosis

layers of intervetebral disc

Intervertebral discs can herniate into the spinal cord, traumatizing the spinal cord and cause hemorrhage, edema, and necrosis

intervetebral disc degeneration (IVDD) and herniation

dogs

IVDD is common in which species

Type I extrusion disc herniation

Type II protrusion disc herniation

acute

onset of Type I disc hernation (extrusion)

Chondrodystrophic (dwarf) breed dogs like Dachshunds, frenchies, basset hounds, corgis

which breeds is IVDD type I more commonly seen

gradual onset

onset of Type II disc herniation (protrusion)

large breed dogs

which breeds is IVDD Type II more commonly seen in

Type II

disc hernation is uncommon in cats but if they do get it, which type do they usually suffer from?

hemorrhagic myelomalacia

ascending and/or descending hemorrhage and necrosis within the spinal cord

disc hernation or other trauma to the spinal cord

cause of hemorrhagic myelomalacia

ascending or descending paralysis and sensory deficits 24 hours after spinal cord injury

presentaiton of hemorrhagic myelomalacia

hemorrhagic myelomalacia

strokes

sudden onset of focal neurological deficits from intracranial vascular event

local ischemia from infarction or hemorrhage

causes of strokes

acute cerebral infarct

red to black, sharply demarcated, wedge-shaped

chronic cerebral infarct

golden brown, depressed, may resolve as shrunken pale scars

- uncommon, affects cats of all ages

- ataxia/circling, seizures, blindness, and postural deficits

- unilateral ischemic necrosis and atrophy of cerebral cortex

Feline Ischemic Encephalopathy (FIE)

middle cerebral artery

damage to which vessel in the brain can cause feline ischemic encephalopathy

fibrocartilaginous emboli (FCE)

degenerative intervetebral disc material extruded into spinal blood vessels and travels to parenchyma of spinal cord, causing infarction

fibrocartilaginous emboli (FCE)

- hemorrhage

- edema

- softening of parenchyma (malacia)

what gross lesions would make you suspect there was a vascular/traumatic injury

dogs

which species is CNS neoplasia most commonly seen in

brachycephalic breeds (boxers or boston terriers)

which dog breed has a increased incidence of CNS tumors

gliomas

which CNS tumors are brachycephalic breeds more common to suffer from?

meningioma

most common CNS neoplasia in dogs and cats

- astrocytoma

- oligodendroglioma

which CNS neoplasia are 2nd most common in dogs

choroid plexus (epithelial tumors) like papilloma, adenoma, carcinoma)

3rd most common CNS neoplasia

leptomeninges

arachnoid and pia mater are collectively referred to as

in choroid plexus within ventricles

pia mater is adhered to the surface of the brain and also

- most common primary intracranial brain tumor of dogs and cats

- can arise from any of 3 meningeal layers

- usually superficial or dorsal on brain or spinal cord, intraventricular also possible (pia mater)

- benign but space occupying

- low recurrence rate following surgical excision

meningioma

discrete, firm to rubbery with meningeal attachment. can find compression of neural tissue beneath

meningioma gross appearance

meningioma

5 times

how much more abundant are astrocytes than neurons in the CNS

gemistocytes

astrocytes that respond to injury by increasing their cytoplasm

alzheimer type 2 astrocytes

astrocytes that appear as clusters of astrocytic nuclei that are swollen and clear. associated with hepatic and renal encephalopathy

form myelin sheath around axon

function of oligodendrocytes

malignant

are glial tumors (astrocytomas and oligodendrogliomas) malignant or benign

- very infiltrative with indistinct margins

- most often found in cerebrum (temporal lobes)

astrocytoma

astrocytoma

- mature dogs

- males

- cerebrum (frontal lobe)

oligodendroglioma

- pink to gray

- soft and gelatinous

- indistinct or sharply demarcated margins

gross appearance of oligodendrogliomas

oligodendroglioma

fried egg appearance

microscopic appearance of oligodendrogliomas

oligodendroglioma

phagocytosis

main function of microglia

choroid plexus

ciliated (modified) cuboidal ependymal epithelium that produces CSF

- within ventricles

- supported by pia mater

ependymal cells

- ciliated cuboidal epithelium

- line ventricles and central canal of spinal cord

- important part of brain/CSF barrier

4th ventricle

most common location for choroid plexus tumors

- vomiting

- positional nystagmus

- head tilt

- tetraparesis

presentation of choroid plexus tumors

rare in all species

ependymoma

- tan to red/grey and nodular

- within ventricles

gross appearance of choroid plexus tumors

hydrocephalus

what can papillomas, adenomas, and carcinomas cause in the brain due to ventricular obstruction

external granular cell layer

which cell layer in the cerebellar cortex is only present in utero or neonates (2-4 week period after birth)

medulloblastomas

which CNS neoplasia is highly malignant and is composed of undifferentiated cells of the neural tube

young animals

medulloblastomas arise from the external granular cell layer of the cerebellum and occur almost exclusively in what kind of animal

calves

medulloblastomas occur most commonly in this species

- grey masses, often in cerebellum

- +/- secondary hydrocephalus

gross appearance of medulloblastomas

- perineural cells

- fibroblasts

- schwann cells

cells in the peipheral nervous system that commonly give rise to neoplasms

schwannoma

benign tumor of schwann cells

neurofibroma

benign schwann and perineural cell tumor (collective term)

peripheral nerve sheath tumor (PNST)

malignant version of schwann or perineural cell tumor

- benign or malignant

- locally invasive

- rarely metastasize

peripheral nerve sheath tumors

neurofibromatosis

syndrome in cattle where single or multiple peripheral nerve sheath tumors develop in multiple anatomic sites

meningitis

inflammation of the meninges

encephalitis

inflammation of the brain

myelitis

inflammation of the spinal cord

meningoencephalomyelitis

inflammation of the meninges, brain, and spinal cord

polioencephalitis

inflammation of the grey matter of the CNS

leukoencephalitis

inflammation of the white matter of the CNS

superficial

where is the grey matter in the cortex of the brain

deep

where is the grey matter in the spinal cord

bacteria

suppurative inflammation is indicative of what type of infection

neutrophils

suppurative inflammation from bacteria has what type of inflammatory cells

mixture of lymphocytes/plasma cells/macrophages

non suppurative infections have what type of immune cells

viral or immune mediated

what is non-suppurative inflammation indicative of?

macrophages +/- neutrophils

what type of inflammatory cells are characteristic of granulomatous or pyogranulomatous infections

- bacteria (mycobacteria)

- fungus

- certain viruses

what can cause granulomatous or pyogranulomatous lesions

parasites

what causes eosinophilic inflammation

hematogenous

how are neurological infections often spread

- subarachnoid barrier

- blood brain barrier

- CSF barrier

barriers that keep out CNS infection

small ruminants

what species does Listeria most commonly affect

goat has ulcer and eats food contaminated with Listeria monocytogenes, bacteria infect peripheral nerves and extend to brainstem/cerebellum

How do small ruminants get affected with Listeria