Forebrain Diseases

Forebrain Diseases
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Cerebrum
Thalamus
Anatomy
Hypothalamus
Telencephalon
Diencephalon
Prosencephalon
(Forebrain)
Cerebellum
Cerebrum
Thalamus
Hypothalamus
Midbrain
Pons
Medulla oblongata
Functions of the forebrain
Function
 
 
 
 
 
Behavior/learning
)!#/# Alertness
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$! Vision
Touch
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perception
Motor
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control**
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Cardinal Sign
 
 
 
 
 
Dementia
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%( &! Obtundation
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Blindness
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Hypalgesia
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Seizures
Diseases with forebrain signs
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Functions of the forebrain
Function
 
 
 
 
 
Behavior/learning
Alertness
Vision
Touch perception
Motor control**
Cardinal Sign
 
 
 
 
 
Dementia
Obtundation
Blindness
Hypalgesia
Seizures
Dementia
Loss of learned behaviors
Abnormal body positions
Courtesy, Dr. John Baird, University of Guelph
20-mo TB filly
Eastern equine encephalitis (EEE)
3-wo 3-mo
Thoroughbred
2-yo TB
TB filly
filly colt
Fluphenazine
Viral
encephalitis?
reaction
Hyponatremia
Dementia contd.
Playing
in water
Teeth grinding
Loss of affinity for dam
8-yo
Quarter
horsestallion
gelding
13-yo
Paso Fino
Hyperammonemia
Suspected
encephalitis
4-do Quarter horse filly
Frontal/parietal trauma
Dementia contd.
Compulsive walking/circling
Head-pressing
13-yo Standardbred gelding
Leukoencephalomalacia
13-yo Quarter horse mare
Gastrointestinal hyperammonemia
Courtesy: Dr. E. Green, Texas A&M
Dementia contd.
Yawning
Hyperresponsiveness
7-mo Quarter Horse colt
Portacaval shunt
filly mare
22-yo 2-yo
mixedTBbreed
Intestinal
hyperammonemia
Cholesterol
granuloma
Self-mutilation
Morbid lesion
Psychological
syndrome
Normal reaction
3-yo Thoroughbred gelding
Rabies
12-yo
13-yo
Thoroughbred
Morgan stallion
mare
Self-mutilation
Stinging nettlesyndrome
reaction
Self-mutilation syndrome
Don’t do this
Do this!!
Dementia - Forebrain
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Functions of the forebrain
Function
 
 
 
 
 
Cardinal Sign
Behavior/learning
Alertness
Vision
Touch perception
Motor control**
Dementia
Obtundation
Blindness
Hypalgesia
Seizures
 
 
 
 
 
Anatomy of Alertness
Cerebellum
Retic
u
lar a
ctiva
ting
I
Smell
Cerebrum
Sensation from
Body and limbs
syst
em
II
Thalamus
Hypothalamus
Vision
Midbrain
Facial sensation
Pons
V
Medulla oblongata
VIII
Head & body motion
But first…..sleep disorders!
2.5 h
0.5 h
Slow-wave
Paradoxic
7-do Morgan filly
Inherited narcolepsy
25-yo Thoroughbred gelding
Paradoxical sleep
Acquired narcolepsy?
Anatomy of Alertness
Adult Paradoxic Sleep
• Sleep deprivation
• True acquired narcolepsy
Retic
ular
I
activ
atin
g sy
st
em
II
Neurotransmitter Balance
+ Hypocretin
+ Norepinephrine/serotonin
-- Acetylcholine
V
VIII
Spinal cord
somatosensory
pathways
Levels of obtundation
Lethargy
Stupor
Semi-coma
Coma
Levels of obtundation
Lethargy
Stupor
Semi-coma
Coma
Levels of obtundation
Lethargy
Stupor
Semi-coma
Coma
Levels of obtundation
Lethargy
Stupor
Semi-coma
Coma
Functions of the forebrain
Function
 
 
 
 
 
Behavior/learning
Alertness
Vision
Touch perception
Motor control**
Cardinal Sign
 
 
 
 
 
Dementia
Obtundation
Blindness
Hypalgesia
Seizures
Blindness
Assumptions
Optic nerves OK
• Test PLR
Can blink
• Test palpebral
Normal
cerebellar cortex
3-month-old Quarter Horse colt
Skull trauma
Functions of the forebrain
Function
 
 
 
 
 
Behavior/learning
Alertness
Vision
Touch perception
Motor control**
Cardinal Sign
 
 
 
 
 
Dementia
Obtundation
Blindness
Hypalgesia
Seizures
Perception of touch/pain
Assumptions
Normal
trigeminal nerve
transmission
• Do V-VII tests
3-mo Quarter Horse colt
Skull trauma
Functions of the forebrain
Function
 
 
 
 
 
Behavior/learning
Alertness
Vision
Touch perception
Motor control**
Cardinal Sign
 
 
 
 
 
Dementia
Obtundation
Blindness
Hypalgesia
Seizures
Seizures
          Seizure - focal
• Pre-ictal
• Snorting
• Vocalizing
• Head-shaking
• Seizure
- partial
• Seizure
- generalized
• Left muzzle twitch
• Tongue movement
• Head turn to right
• Circling to right
• Post-ictal
4-yo Palomino gelding
EPM?
• No menace L (90
• Lethargic (5 min)
Seizure - generalized
From: Delahunta A.Clin Tech Eq
Pract 2006;5:74. With permission
min)
Acute management, adults
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  IG Mayhew. Large Animal Neurology, ed 2, 2008.
Maintenance management, adults
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  & IG Mayhew. Large Animal Neurology, ed 2, 2008.
Functions of the forebrain
Function
 
 
 
 
 
Behavior/learning
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Alertness
Vision
Touch
perception
Motor
##
control**
Cardinal Sign
 
 
 
 
 
Dementia
Obtundation
Blindness
Hypalgesia
Seizures
Case 2
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  Neurologic Exam
Clinical Sign
o  Lethargic
o  Defective vision
o  No contact
with dam
o  No menace either
side
o  Touch perception
present
o  Seizures
Sudden loss of affinity for dam
Clinical Sign
Lesion Location
o  Lethargic
  Any brain
o  Defective
vision
  II, midbrain, forebrain
o  No contact
with dam
  Forebrain
o  No menace on
either side
  II, VII, cerebellum, midbrain
bilateral forebrain
o  Touch perception
present
  Competent V, brainstem
forebrain function
o  Seizures
  Forebrain
Neuroanatomic localization
    Additional findings
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Clincial course
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Menace - Palpebral reflex (V - VII)
Fractured stylohyoid
3-yo mixed breed gelding
Menace - Cerebellum
3-month-old Arabian colt
Cerebellar abiotrophy
Without cataplexy
  %$&!
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    Narcolepsy with cataplexy
  Collapse with atonia/areflexia
  Benign
  Familial/persistent
  Morgan
  American Miniature Horse
  Role of hypothalamic nuclei
  hypocretins
Narolepsy-Cataplexy contd.
  #!$
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Functions of the forebrain
Function
 
 
 
 
 
Behavior/learning
"'
Alertness
Vision
!
Touch
perception
((
control**
Motor
Cardinal Sign
  Dementia
  !
Obtundation
  
Blindness
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Hypalgesia
  
$!
  Seizures
Forebrain blindness
2-yo Thoroughbred filly
EEE