Final: Neuro Flashcards
What distinguishes a pathologic nystagmus from normal nystagmus?
Pathologic if occurs in absence of head movement
How do we assess smell in horses?
If they are eating they can smell
What is the best way to assess vision?
Obstacle course/ Maze
Can blindfold one eye and then the other if suspect unilateral vision problems
Which nerves are most commonly affected when there are vision problems? Of these which is most comon?
V, VII, VIII
VII (Because it is superficially located)
What nerve is affected if the masseter is atrophied? What does it mean if the jaw is dropped?
CN V
Bilateral nerve damage
What horse-specific signs are associated with Horner’s?
Asymmetric nasal airflow (localized congestion)
Unilateral sweating on neck
(Also abnormal position of eyelashes)
When CN VII is damaged on the right, to which side does the muzzle deviate?
To the normal side (left)
When CN VIII is damaged, in which direction is the head tilt? To which side do they lean and fall?
Toward lesion
To affected side
The fast phase of nystagmus is _____ the lesion.
Away from
What does Dog Sitting imply?
Neurologic disease of some kind, often the case that it is more severe in the hind limbs
R/O Weakness since +++ weight in hind
If you notice a horse being as affected or more affected in the forelimb than the hind limbs what lesion comes to mind?
Low cervical (C6-7) lesion or cranial intumnescence involvement
In order to evaluate gait a grading system is used. How many grades are there? Which three parameters are used IN EACH LIMB for evaluation and what grades are used for these?
6 grades (0 - 5) 5 is most severe- recumbent
Weakness
Spasticity
Ataxia
Graded 0 to 4+
When you grade the gait and posture and note that only weakness and spasticity are abnormal (i.e. no ataxia) what does this indicate?
Weakness or lameness rather than neurologic disease
What words are used to describe weakness when assessing gait and posture?
“ings”
Toe dragging
Knuckling
Buckling
Stumbling
What can cause toe dragging?
Mechanical disruption (tendon rupture, DJD…)
Weakness
What are the 2 causes for spasticity?
Hypermetria: excessive joint flexion
Hypometria: short choppy gait, ‘tin soldier’ gait
What does it indicate if a horse vacillates it’s leg in the air before setting it down?
Ataxia
What signs in addition to ataxia and head pressing do you expect to see with cerebral disease? What other conditions cause similar sypmtoms?
Mentation and behavior abnormalities
Circling
Seizures, semi-coma, coma, death
Other conditions: Sodium imbalance, Liver disease, Moldy corn poisoning (leukoencephalomalacia- corn looks pink to brown), trauma
Does lack of a fever rule out infectious causes for cerebral disease?
Nope
What does a bacterial CNS infection do to the glucose in the CSF?
Decreases
What are the 2 locations for CSF sampling? Where should a sample be taken if you have a C2 lesion?
Atlantooccipital space
Lumbosacral space
C2 lesion= Lumbosarcal (must consider flow of CSF, it has to ‘flow’ past the lesion for the fluid to be diagnostic for the lesion)
Which type of CSF tap must be done under anesthesia?
Atlantooccipital
What is the normal TP in CSF? WBC? RBC? Color?
TP <100 mg/dl
WBC <5-6/microL
RBC none
Correction factor (blood contamination)= 1 WBC for every 500 RBC
Clear
You obtain a CSF tap and the values are:
WBC= 13
RBC= 5000
What is the corrected WBC value?
3
- 5000/500= 10*
- 13 WBC - 10 WBC = 3 WBC = WNL*
What to platelets in a CSF sample indicate?
Contamination (iatrogenic)
Or very recent (<8hrs) true hemorrhage
What test is used to determine whether antibodies are being made in the CNS?
Comparson of serum and CSF:
Albumin quotient (status of BBB, if elevated disrupted)
IgG index (if increased indicated AB production in CNS)
Antibody index (for antigen-specific antibodies)
What are your top DDx for a horse with hypersensitivity, hyperesthesia, muzzle fasciculation, and twitching? What in the CSF indicates one over the other?
West Nile Virus
Rabies
If there are neutrophils in the CSF think rabies (other viruses there will be lymphocytes and plasmacytes)
What is the most common form of rabies in horses?
Paralytic
Others are dumb and furious
How can an ante-mortem diagnosis of rabies be made?
Tactile Hair IFA
However many false negatives depending on what phase of rabies the horse is in when the sample is taken
What forms of equine viral encephalitides are most severe in horses?
EEE
VEE