Neurological cases

Question 1

Which nerve innervated the masseter muscles?

Answer 1

Trigeminal

Question 2

Which nerves control the palpebral reflex?

Answer 2

Sensory fibres Trigeminal nerve (V)
Motor fibres Facial nerve (VII)

Question 3

Neuro exam findings:
Right eye:
- Negative palpebral reflex (medial and lateral canthus)
- Positive menace response
- Negative direct pupillary light reflex
- Positive dazzle reflex
- Negative corneal reflex

Neurolocalisation?

Answer 3

Brainstem:
- Oculomotor (III)
- Trigeminal (V)
+/- Abducens (VI)

Question 4

How can you determine if there are deficits with the abducens nerve?

Answer 4

Responsible of eye position and movement
No strabismus present → presume functional

Question 5

22 year old mare
Lameness exam (hind limbs) last 4 months
Improves with NSAIDs
Today: almost fell off the horse trailer ramp on arrival at clinic→ Neuro exam
- ve menace on L side
- Ataxia with hypermetry in all 4 legs (worse on left side)

Neurolocalisation

Answer 5

Cerebellum (left)

Question 6

14 year old gelding
No change in management
Owner reports area of focal sweating

initial diagnosis?

Answer 6

This horse has Horner’s syndrome

Question 7

Describe how Horner’s syndrome effects sweating

Answer 7

Sympathetic → “Fight or flight” response → ↑ sweating

Horner’s: lack of sympathetic supply → ↓ sweating

Question 8

So why do horses with horners sweat?

Answer 8

Local vasodilation → ↑ local perfusion and local temperature → more circulatory adrenergic agonists reach the sweat glands → ↑sweating