L02: Forebrain Disease in the Vet Patient (Seneca) Flashcards
1
Q
What does forebrain include?
A
Cerebrum (telencephalon)
Thalamus, Hypothalamus (diencephalon)
2
Q
5 lobes of cerebrum and functions
A
1) frontal - motor cortex
2) parietal - somatosensory cortex
3) temporal - auditory complex
4) occipital - visual cortex
5) piriform - olfactory complex
3
Q
blood supply to brain (5 arteries)
A
From Circle of Willis: -Rostral cerebral -Middle cerebral -Caudal cerebral -Rostral cerebellar From basilar artery: -Caudal cerebellar
4
Q
Species variation in blood supply to brain: DOG
A
- blood to rostral half (FOREBRAIN) supplied by internal carotid a.
- caudal half supplied by vertebral a.
5
Q
Species variation in blood supply to brain: CAT/SHEEP
A
entire brain supplied by maxillary a.
cats: basilar a. carries arterial blood AWAY
6
Q
Species variation in blood supply to brain: BOVINE
A
entire brain supplied by a mixture of maxillary and vertebral blood.
7
Q
6 categories of lesions**
A
1) intracranial
2) C1-C5
3) C6-T2
4) C6-T2
5) L4-S3
6) Lower motor neuron (diffuse)
8
Q
where do seizures come from?**
A
forebrain ONLY
9
Q
CS of forebrain disease
A
- Seizure
- altered mentation/behavior change/dementia/loss of training
- pacing, wandering, wide circles (typically to SAME side as lesion)
- head turn to SAME side as lesion
- postural reaction deficits (OPPOSITE side as lesion)
- visual impairment, cortical blindness (OPPOSITE side)
- head pressing, star-gazing, fly-biting
- hemiparesis (OPPOSITE side)
- NORMAL gait (but may have proprioceptive ataxia)
- hemi-inattention, hemi-neglect
- brain pain (flinches when clamp on head or neck)
10
Q
CS NOT assoc. with forebrain disease
A
- head tilt
- nystagmus
- stupor, coma (typically comes from brainstem)
- ataxia
- abnormal spinal reflexes
- significant cranial n. deficits
- intention tremors (come from cerebellum)
11
Q
where does coma come from?
A
brainstem
12
Q
where do intention tremors come from?
A
cerebellum
13
Q
why are postural reaction deficits on the CONTRALATERAL side in forebrain disease?
A
crossing over occurs in the medulla oblongata
14
Q
where does crossing over (decussation) of proprioceptive tracts occur?
A
medulla oblongata
15
Q
proprioceptive information remains ipsilateral to level of:____
A
midbrain
16
Q
diagnostic work-up for forebrain disease
A
- Hx, neuro exam
- minimum database
- MRI (superior to CT)
- CSF analysis
- infectious disease testing if indicated
17
Q
DAMNITV
A
acronym for common forebrain diseases and their clinical presentations. Stands for: Degenerative Anomalous Metabolic Neoplasia/Nutritional Inflammatory/Infectious Toxin/Trauma Vascular
18
Q
why are visual deficits on contralateral side in forebrain disease?
A
because of crossover at optic chiasm
19
Q
DEGENERATIVE includes:
A
Lysosomal storage diseases
Leukodystrophy
Cognitive Dysfunction
20
Q
chars. of lysosomal storage diseases
A
- rare
- usually autosomal recessive
- accumulation of metabolic by-products usually due to a defective enzyme
- leads to cellular dysfunction
- usually develop progressive encephalopathy soon after birth
21
Q
chars. of cognitive dysfunction
A
- mostly older dogs
- similar to human Alzheimer’s
- accumulation of beta-amyloid in the brain, which coalesce to form neuritic plaques
22
Q
CS of cognitive dysfunction
A
- progressive cognitive impairment
- inactivity, abnormal sleep/wake cycle
- wandering/pacing
- dementia, incontinence
- anxiety
- failure to recognize people
- dec. interaction
- hearing loss, vocalization
- cats can develop aggression
23
Q
Dx of cognitive dysfunction
A
-Hx, CS
+/- abnormal MRI (cerebral atrophy, ventricular enlargement, microhemorrhage, infarct, interthalamic adhesion)
24
Q
Tx of cognitive dysfunction
A
- no known cure
- Optional: Selegiline, SAM-e, acupuncture
25
ANOMALOUS includes:
Congenital Hydrocephalus
| Primary Epilepsy
26
chars. of Congenital Hydrocephalus
- toy/brachiocephalics
- excess CSF
- destruction of ependymal lining of ventricles
- neuronal injury in the cerebral cortex and compromise of cerebral vasculature
- damage to periventricular white matter
- can be asymptomatic
- can cause dysfunction from compression and stretching of brain parenchyma
27
General Exam findings of Congenital Hydrocephalus
- dome-shaped head
- open fontanelle or larger calvarial defect
- ventrolateral strabismus (due to orbital malform.)
28
Neuro Exam findings of Congenital Hydrocephalus
- typically apparent by 6mo
| - behavior change, obtundation, dementia, circling, pacing, restlessness (uncommonly seizures)
29
Tx of Congenital Hydrocephalus
```
Reduce CSF production with:
-Prednisone
-Omeprazole (proton pump inhibitor)
-Furosemide
Surgery: ventriculoperitoneal shunt (shunts extra fluid to abdomen)
*Can NOT address cerebrocortical damage*
```
30
chars. of Primary Epilepsy***
- no identifiable brain abnormality
- usually younger pure-bred dogs
- usually generalized seizures during rest/sleep
- highly variable seizure frequency
- more common in dogs
31
most commonly used drugs to tx primary epilepsy***
```
Phenobarbital
Potassium Bromide (KBr)
Levetiraceta
Zonisamide
Emergency: Diazepam IV
```
32
METABOLIC includes:
Hepatic encephalopathy
| Hypoglycemia
33
2 causes of hepatic encephalopathy
liver failure
| portosystemic shunt
34
CS of hepatic encephalopathy
```
obtundation (altered consciousness)
pacing
head pressing
visual deficits
head pressing
seizures (infrequent)
*may be assoc. with feeding*
copper colored eyes in cats
```
35
Dx of hepatic encephalopathy
```
Hx
Pre and post-prandial bile acids***
inc. ALT/ALP, NH3
ammonium biurate crystals in urine
scintigraphy
```
36
Tx of hepatic encephalopathy
Sx shunt attenuation
low protein diet
lactulose (binds NH3)
abx
37
causes of hypoglycemia
- glycogen depletion in very young, small puppies/kittens
- excess insulin secretion (insulinoma)
- insulin overdose in diabetic animals
- Addison's disease
- Liver failure
- Toxin (ie. xylitol)
38
CS of hypoglycemia
- tremor
- vocalization
- altered mental status
- seizure
- visual dysfunction
etc. ..
39
Most common primary forebrain neoplasms
```
Meningioma (most common in dogs and cats!)
Glioma
Choroid plexus tumors
Lymphosarcoma
Histiocytic sarcoma
```
40
what produces CSF?
choroid plexus
41
most common secondary forebrain neoplasms
```
hemangiosarcoma
adenocarcinoma
lymphoma
melanoma
nasal/frontal sinus carcinoma
calvarial tumor
pituitary tumor
peripheral nerve sheath tumor
```
42
CS of neoplasm effecting forebrain
(highly variable)
- behavior change, circling, head press, visual deficits, hemi-inattention
- proprioceptive deficits
- gradual development
- endocrine signs w/ pituitary tumors
43
Tx of neoplasm effecting forebrain
sx, radiation, chemo
44
NUTRITIONAL causes of forebrain dz
thiamine deficiency (all fish diet in cats)
hypoglycemia
hypocalcemia
45
INFLAMMATORY causes of forebrain dz
Immune-mediated:
- Necrotizing Leukoencephalitis (NLE)
- Necrotizing Meningoencephalitis (NME)
- Granulomatous Meningoencephalitis (GME)
- Meningoencephalitis of unknown cause
46
INFECTIOUS causes of forebrain dz
More common in cats, pigs
- Bacterial
- Protozoal
- Viral (ie. West Nile Virus Encephalomyelitis, Equine Herpes virus myeloencephalopathy, Rabies)
- Fungal
- Rickettsia
- Parasitic
- Equine infectious encephalitidies (including EEE, WEE, VEE)
47
Ex. of protozoal cause of infectious forebrain dz
Equine Protozoal Myeloencephalitis (EPM)
| -Apicomplexan protozoa (Sarcocystis neurona**)
48
Dx of infectious forebrain dz
CSF analysis: inc. WBCs, elevated protein lvls
| Serology
49
Tx of infectious forebrain dz
Drugs that cross BBB:
- Abx: doxy, clindamycin, sulfas
- Immune suppression: pred, cyclosporine, etc.
50
TOXIN-related causes of forebrain dz
- xylitol
- narcotics
- ivermectin
- rodenticide
- methylxanthines
- lead
- strychnine
- organophosphates
- pyrethrins
- ethylene glycol
51
TRAUMA-related causes of forebrain disease in NEONATES
narrow birth canal
oversized cranium
forced whelping/fetal extraction
52
TRAUMA-related causes of forebrain disease in SMALL BREEDS
- mishandling
- Hit by car
- blunt or penetrating trauma
53
TRAUMA-related causes of forebrain disease in LARGE BREEDS
HBC
| blunt or penetrating trauma
54
TRAUMA-related causes of forebrain disease in FELINES
High rise fall
HBC
blunt or penetrating trauma
55
Why are felines more at rick for penetrating skull injury compared to dogs?
thinner calvarium, reduced muscle mass
56
VASCULAR-related causes of forebrain dz
```
Brain infarct (stroke) (non-hemorrhagic or hemorrhagic)
Hypercoagulability
Hyperviscosity
IV neoplasia
Atherosclerosis
```
57
causes of brain infarct
Hypertension (1ary or 2ary to hyperadrenocorticism, renal dz, pheochromocytoma)
Cardiac dz
58
Atherosclerosis most common in what breed?**
Schnauzer
