Diffuse Brain / Bilaterall symmetrical Forebrain Disease

Question 1

Why do diffuse brain diseases present as bilateral forebrain disease?

Answer 1

Cerebral neurons are largest population of metabolically active neurons so they’re the first to show disease.

Question 2

What diffuse brain diseases can be rapidly reversed?

Answer 2

Metabolic, Nutritional, Toxic and Vascular if they are identified

Question 3

What diffuse brain diseases can benefit from “routine and commonly available tests?

Answer 3

Metabolic, Nutritional, Toxic and Vascular

Question 4

What does T2*GRE MRI imaging show?

Answer 4

HEMORRHAGE
used for Cognitive Dysfunction Syndrome aka Canine Dementia
- will see multiple pinpoint dark spots indicating hemorrhage

Question 5

Histopath of neurons with Canine dementia show what?

Answer 5

Amyloid plaques in both humans and dogs in atrophied brain matter

Question 6

Clinical signs of dog/cat with Dementia?

Answer 6

D - disorientation
I - interaction changes
S - sleep/wake cycle abnormalities
H - house soiling
A - activity changes or Anxiety

Question 7

TX of Cognitive Dysfunction Syndrome?

Answer 7

combo of pharma and behavior modification

• Selegeline ~ Anipryl only approved drug
• environmental enrichment
• antioxidants (ess. fatty acids, SAMe, etc.)
• behaviorist referral to make sure no other disease present

Will not cure patients, only delay onset of other clinical signs.

Question 8

Age of presentation of Cognitive Dysfunction syndrome

Answer 8

geriatric

Question 9

Define congenital hydrocephalus

Answer 9

Internal, non-obstructive hydrocephalus without apparent cause

Question 10

What does fusion of the rostral colliculi show you?

Answer 10

Stenosis or Atresia of the mesencephalic aqueduct

Question 11

CS of hydrocephaly

Answer 11

“Setting Sun Strabismus” - orbits formed too shallow
enlarged, open fontanelle
Dome-shaped skull
Neuro deficits: seizures, circling, bizarre behaviors

Degree of clinical signs more related to RATE of enlargement than amount

Question 12

What indicates specifically that the 4th ventricle is involved in hydrocephaly?

Answer 12

cerebellovestibular signs – the 4th ventricle is just underneath and if it’s putting pressure on the cerebellum you will see signs.

Question 13

What’s more important, rate or amount of enlargement in hydrocephaly?

Answer 13

RATE is more important

Question 14

Define Lissencephaly

Answer 14

abscence or paucity (scarce formation) of gyral formation and pachygyri (thickening of gyri)

Rat brain!

Question 15

What is the MOST SEVERE disease of neurobiotaxis that is still compatible with life?

Answer 15

Lissencephaly - the absence or pauctiy (scarce formation) of gyral formation and pachygyri (thickening of gyri)

Question 16

what is neurobiotaxis?

Answer 16

the embryological organization the layers of the nervous system in the brain.

mutation prevents cortex from forming correctly

Question 17

What breed is pre-disposed to Lissencephaly?

Answer 17

Lhasa Apso

Question 18

Most common clinical sign of lissencephaly

Answer 18

medically refractory seizures; “Rat brain” smooth cerebrum

Question 19

TX of lissencephaly

Answer 19

try and control seizures; most cases are identified at necropsy

seizures don’t go away but you can control with anti-convulsants

Question 20

2 most common metabolic diseases that cause diffuse brain

Answer 20

hypoglycemia

hepatic encephalopathy

Question 21

2 major histopath changes in Hepatic Encephalopathy

Answer 21

1. Polymicrocavitations of white matter (spongy change from edema of white matter)
2. Alzheimer’s Type 2 Astrocytes (clear, swollen nuclei)

Question 22

CS of thiamine deficiency

Answer 22

Brainstem issue:

• anorexia
• vestibular ataxia
• mydriasis
• seizures, tetraparesis
• cervical ventroflexion

Question 23

Thiamine deficiency causes these lesions in the brain

Answer 23

in the BrainSTEM: Bilateral hemorrhagic necrosis of brainstem

Question 24

What’s the underlying etiology of ivermectin toxicity?

Answer 24

mutation in MDR-1 gene

Question 25

What does MDR-1 gene normally code for?

Answer 25

enzyme that pumps toxic drugs out of the BBB

Question 26

TX for ivermectin therapy

Answer 26

lipid emulsion for lipid sink

Question 27

How does Lead damage the brain

Answer 27

CNS Ischemia because lead interferes with hemoglobin synthesis

Question 28

how can you DX lead tox?

Answer 28

Blood [lead] > 0.35ppm
RBC w/ basophilic stippling
metaphyseal lead lines

Question 29

how do you tx lead tox?

Answer 29

Chelation with SUCCIMER

Question 30

Histopath of lead tox

Answer 30

status spongiosus (diffuse brain edema)
capillary proliferation
b/c of ischemia - cerebrocortical necrosis

Question 31

most common cause of Global Ischemia

Answer 31

Anesthetic accident or CPA (cardiopulmonary arrest)

Question 32

risk factors for Global Ischemia

Answer 32

Ketamine used in anesthesia
Pre-existing resp or card. disease
Poor monitoring: prolonged hypotension and hypoxia

Question 33

order of susceptible neurons in brain to ischemia

Answer 33

Cerebral cortex -> hippocampus -> basal nuclei -> Cerebellum

Question 34

CS of global ischemia

Answer 34

cerebral signs progressing to cerebellar signs:

• seizures
• depressed
• thalamocortical blindness
• cerebellar ataxia

Question 35

General pathophys of FOCAL brain disease

Answer 35

ultimately increase intracranial pressure
CS dependent on location
Usually require advanced imaging, CSF analysis, and other ancillary neurodiagnostics.