Equine Neurologic Exam

Question 1

Describe NORMAL CSF in the horse

Answer 1

Clear, colorless
TNCC < 6
Majority mononuclear cells
protein < 100
RBC 0-1

Question 2

What does xanthochromia indicate in regard to CSF cytology?

Answer 2

xanthochromia is when the CSF appears more yellow (normal CSF is clear)

xanthochromia indicates that RBCs were metabolized due to vasculitis or trauma.

Question 3

what woudl you predict the TNCC would be in the CSF of a horse with bacterial meningitis?

Answer 3

TNCC elevated due to neutrophils

Question 4

what can you infer about an elevated protein for a horses CSF?

Answer 4

this is a non-specific finding and is suggestive of inflammation

Question 5

what do you predict the TNCC would be in a horse with viral encephalopathy?

Answer 5

TNCC elevated due to mononuclear cells (monocytes or lymphocytes)

Question 6

How do you perform the thoracolaryngeal adductor response (slap test) and what is it evaluating?

Answer 6

Slap the horse over the left withers and simultaneously feel the throat for right arytenoid abduction

This tests the cervical spinal cord (af), the nucleus of CN X, and the vagus nerve + recurrent laryngeal nerve (ef).

Question 7

What are components of the ‘static’ neuro exam? (there are 8)

Answer 7

1. mentation
2. stance
3. cutaneous reflexes
4. tail tone
5. muscle symmetry
6. palpation for pain and range of motion
7. cranial nerve assessment
8. slap test

Question 8

Which areas are being assessed when performing the menace response?

Answer 8

CN 2 (sight)
Brain
CN 7 (blink)

Question 9

What is the dazzle assessing?

Answer 9

CN II (sight)
brainstem

google says: CN II, the rostral colliculus, the the hypothalamus, the visual cortex, and CN VII.

Question 10

what is PLR assessing?

Answer 10

CN II (sight)
CN III (pupil constrict.)

Question 11

what CNs does the palpebral reflex assess?

Answer 11

CN V (sensory)
CN VII (motor, blink)

Question 12

If a horse has asymmetry in the face (eye drooping, ear drooping, and masseter msucle atrophy), what cranial nerves are likely damaged?

Answer 12

CN VII (motor to muscles of facial expression)

CN V (motor to muscle of mastication)

Question 13

If a horse couldn’t feel you touching it’s face, which CN is likely damaged?

Answer 13

CN V (facial sensation)

Question 14

You are called ot a farm because the owner reports her horse is unable to keep food in its mouth. Upon examining the horse, you find that the jaw tone is loose and the tongue is hanging out. Which CNs might be damaged?

Answer 14

CN V – jaw tone, mastication

CN XII - tongue tone

CN VII – prehension

Question 15

what is the function of CN IX, X, and XI?

Answer 15

to protect the airway by closing the arytenoids and bringing up the epiglottis.

Question 16

What are components of the ‘dynamic’ neuro exam?

Answer 16

1. walk and trot in straight line
2. serpentine walk
3. walk in circles
4. walk with head elevated
5. walk up/down hill and curb
6. tail pull

Question 17

Describe a grade 2 versus grade 3 on the modified mayhew grading scale

Answer 17

Grade 2 – consistently abnormal under special circumstances (ex. during the serpentine or hill walks)

Grade 3 – abnormal all the time

Question 18

Describe the difference between Grade 4 and Grade 5 on the Modified Mayhew grading scale

Answer 18

Grade 4 – extremely ataxic and may fall

Grade 5 – down and unabe to rise

Question 19

Describe the difference between Grade 1 and Grade 2 on the Modified Mayhew Grading Scale

Answer 19

Grade 1 – inconsistently abnormal under special circumstances

Grade 2 – consistently abnormal under special circumstances

Question 20

Where would you localize a lesion to if the patient had mentation changes, head pressing, circling, central blindness, oand/or seizures?

Answer 20

the brain (CNS)

Question 21

Where would you localize a lesion to if the patient was somnolent and had multiple CN deficits?

Answer 21

the brainstem

Question 22

where would you localize a lesion to if the patient had a hypermetric gait, intention tremors, and/or paradoxic vestibular signs (head tilt and loss of balance contralateral to the side of the central lesion)?

Answer 22

cerebellum

Question 23

T/F: a patient with a normal mentation and one or more cranial nerve deficits has peripheral nervous system disease

Answer 23

true – if it were central, there would be a change in mentation.

Question 24

Which 2 conditions are good examples of diseases that would cause deficits in CN VII and VIII?

Answer 24

Temporohyoid osteoarthropathy (THO) and otitis media/interna

Cranial nerves 7 and 8 exit the skull in close proximity to one another, traveling through the guttural pouch and past the inner ear together.

Question 25

T/F: guttural pouch disease can cause deficits in CN IX, X, and XII

Answer 25

true – these cranial nerves run through the guttural pouch

Question 26

What differentiates paradoxical vestibular disease from peripheral and central?

Answer 26

in both peripheral and central vestibular disease, the patients head tilt would be TOWARD the lesion, they would lean/circle TOWARD the lesion, and the nystagmus would have a fast-phase AWAY from the lesion.

Whereas in paradoxical vestibular disease, the head tilt is AWAY from the lesion, the lean/circle is AWAY from the lesion, and the nystagmus fast-phase is TOWARD the lesion.

Question 27

Compare and contrast the character of the ataxia in peripheral vs central vs paradoxical vestibular disease

Answer 27

peripheral – base-wide stance and staggering

central – proprioceptive deficits

paradoxical – hypermetrria, ipsilateral proprioceptive deficits

Question 28

If a horse had a lesion in the C1-C6 spinal cord, what would be the result/deficit?

Answer 28

all 4 limbs would be affected and typically the pelvic limbs are worse than the thoracic because the pelvic limb motor tracts sit lateral to the thoracic limb motor tracts and are affected first.

Question 29

Where would the lesion be if you had the following deficits:

• All 4 limbs affected (decreased proprioception, ataxia, paresis)
• weakness and toe dragging in the thoracic limbs

Answer 29

C6-T2

The weakness and toe dragging are lower motor neuron signs.

Question 30

Where would the lesion localize to for the following deficits?
Thoracic limbs normal
Pelvic limbs – weakness, toe-dragging or hypermetria
Urinary and fecal incontinence but bladder is distended and NOT easily expressed.

Answer 30

T3-L2

Question 31

What neuro exam findings would be present in a horse with a L3-S3 lesion?

Answer 31

• Normal thoracic limbs
• Pelvic limbs – toe dragging and weakness
• Fecal and urinary incontinent (easily expressed bladder)
• Poor tail tone

Question 32

Where would you localize a lesion based on the following findings?
No ataxia
Fecal and urinary incontinent
+/- sabulous cystitis

Answer 32

S3-caudal

Question 33

What diagnostic test can be used to diagnose CSM?

Answer 33

Myelogram – inject iodinated contrast into the subarachnoid space to look for narrowing of the dye columns.
highly specific, but low sensitivity

Question 34

Which diagnostic is best for diagnosing THO?

Answer 34

CT – you will be able to see bony proliferation

Question 35

Where is the easiest location to collect CSF from in horses? (easy meaning no ultrasound needed)

Answer 35

lumbosacral space

Locate the LS space, clip and prep, block the skin, sedate horse and have them in stocks with skilled handler, insert 18g 5.5” spinal needle and advance until subarachoid space is penetrated. Attached the syringe and aspirate 1-2 mL of fluid.

Question 36

Where can we do ultrasound-guided CSF taps in horses?

Answer 36

C1-C2

Question 37

Which CSF tap location requires general anesthesia?

Answer 37

Atlantooccipital space

Place horse under gen anesthesia and flex their poll. Locate the AO space, clip, and clean. Use 18g, 3.5” spinal needle to advance into the subarachnoid space.