Neuro Emerg 6-16

Question 1

If a lesions is restricted to one cerebral hemisphere, what are the expected clinical signs?

Answer 1

• obtundation
• contralateral visual and menace deficits
• contralateral hemiparesis
• contralateral loss of placing reactions
• circling towards the affected side

e.g., Left lesion
> r-sided loss of vision and menace
> r-sided hemiparesis and loss of placing reaction
> l-sided circling

Question 2

What is the site of lesion causing decerebrate rigidity and how is the rigidity caused and what are the clinical signs

Answer 2

lesion of the midbrain or cerebrum - causing functional separation of the cerebrum from the brainstem

loss of inhibition of the vestibulospinal and reticulospinal tracts

signs:
* altered mentation (usually comatose)
* rigid extension of all limbs
* opisthotonus

Question 3

What does 1-3 days old hemorrhage look like on T1, T2 or T2 with flare MRIs?

Answer 3

T1 isointensity
T2 hypointensity
T2 marked hypointensity

due to deoxyhemoglobin

Question 4

List advanced diagnostics you could apply in an animal presenting in a coma

Answer 4

• MRI
• CT
• CSF analysis - caution!
• Brainstem auditory evoked response
• Electroencephlaography
• Somatosensory evoked potential

preserved BAER indicated preserved brainstem function

preserved EEG indicated preserved cerebral function

Question 5

What are the most common signs of hydrocephalus?

Answer 5

• altered mentation
• inappropriate behavior
• cortical blindness
• seizures
• ventrolateral strabismus

Question 6

How does brain hypoxia cuase cell death?

Answer 6

• loss of energy metabolism
• secondary effects of excitatory neurotransmitters (buildup of glutamate and aspartate)
• intracellular Ca increase
• free radical formation

Question 7

What are the most vulnerable brain structures to hypoxia?

Answer 7

• cerebral cortex
• hippocampus
• certain basal nuclei
• thalamus
• cerebellar purkinje cell layers

Question 8

What are typical MRI findings of hypertensive encephalopathy?

Answer 8

FLAIR MRI
hyperintensity within the white-matter tract of the forebrain

Question 9

What is the prodrome or aura?

Answer 9

prodrome - behavioral change hours to days before seizure

auro - subjective sensation marking the onset of a seizure

Question 10

What are the typical resting and threshold potentials of neurons?

Answer 10

resting -70 mV
threshold -55 mV

Question 11

What are the main excitatory and inhibitory neurotransmitters of the brain?

Answer 11

Glutamate

GABA

Question 12

How is glutamate produced an recycled?

Answer 12

produced via glutaminase from glutamine (in the mitochondria)

synaptic glutamate»_space; taken up by astrocytes»_space; metabolize it back to glutamine

Question 13

What are typical signs of forebrain lesions?

Answer 13

• altered behavior
• altered consciousness
• contralateral facial sensory awareness impaired
• contralateral proprioceptive deficits
• hemi-neglect
• central blindness/cortical blindness
• ipsilateral head turn (not tilt!) or circling
• seizures

Question 14

Do disorders of the LMN cause ataxia?

Answer 14

no

Question 15

What are typical signs of thiamine deficiency?

Answer 15

• vestibular and proprioceptive ataxia
• blindness
• mydriasis
• cervical ventroflexion

Question 16

Which tract of the UMN system does not inhibit the lower motor neurons?

Answer 16

vestibulospinal tract

Question 17

Describe exam findings with UMN versus LMN urinary bladders

Answer 17

UMN: large, firm, difficult to express - over-flow incontinence if ver large
LMN: large, flaccid, easily expressed (but incomplete) - frequent urine dribbling

Question 18

What parts of the spine can be evaluated with the cutaneous trunci reflex?

Answer 18

C8 - L3

Question 19

What are the neurolocalizations for an UMN versus LMN urinary bladder?

Answer 19

UMN - cranial to S1

LMN - caudal to S1

Question 20

Fill in the blanks

Answer 20

Question 21

How common is megaesophagus in polyradiculoneuritis?

Answer 21

not a feature of coonhound paralysis

Question 22

What leads to paralysis in polyradiculoneuritis?

Answer 22

destruction of myelin sheets of the ventral roots and peripheral nerves

mononuclear interstitial infiltrate

Question 23

What are the clinical characteristics of Polyradiculoneuritis?

Answer 23

• acute onset flaccid paraparesis - then progressing to the forelimbs (progression typically takes 4-5 days)
• CN typically normal (dysphonia and facial weakness possible though)
• no megaesophagus
• normal perineal reflex and urination
• early: hyperaesthesia
• mental status stays normal, may wag tail
• EMG only altered 5-7 days after onset of signs (not helpful early on)
• CSF: protein elevation but normal cell coutn and cytology
• course of disease 4-6 weeks

Question 24

What is the most common causative agent for discospondylitis?

Answer 24

Stpahyloccocus aureus

Question 25

What are the most common spinal neoplasias in dogs versus cats?

Answer 25

dogs: fibrosarcoma, osteosarcoma cats: lymphoma, osteosarcoma

Question 26

List the parts of the visual system

Answer 26

* retina * optic nerves * optic chiasm * optic tracts * lateral geniculate nucleus * optic radiations * visual cortices (occipital cortices)

Question 27

What are the parts of the vestibular system?

Answer 27

* receptor organ - i.e., inner ear * vestibular nerve * brainstem nuclei in the medulla oblongate

Question 28

What causes leaning towards the side in vestibular disease?

Answer 28

leaning/falling towards the affected side vestibular system affects limb tone via the vestibulospinal tract - affects the extensor muscles on the same side affected side >> decreased extensor tone >> falling to that side

Question 29

What are signs typically seen with both peripheral and central vestibular disease?

Answer 29

* vestibular ataxia * nystagmus * positional strabismus * head tilt

Question 30

What signs are indicative of central vestibular disease over peripheral?

Answer 30

* altered mentation * proprioceptive deficits + proprioceptive ataxia * UMN signs

Question 31

How can the character of the nystagmus help differentiate peripheral versus central vestibular disease?

Answer 31

both: horiztonal or rotary central only: vertical or variable nystagmus central: slower nystagmus pace than peripheral

Question 32

What is paradoxical vestibular disease?

Answer 32

cerebellar lesions can occasionally cause vestibular disease on the contralateral side