Neuro exam and diag testing

Question 1

what are the initial things you are looking for during a neuro exam?

Answer 1

Changes in mentation: Abnormalities of cerebral function, Abnormal states of wakefulness
Abnormal posture: (Cerebellar disease intention tremor - very rare), head tilt

Question 2

How do you test optic nerve function in the horse?

Answer 2

Menace response
* Blink - Facial nerve
* Withdraw response - Central processing (forebrain) – cerebral and cerebellar
* Learned response - Absent for first 14 days of life

Pupillary light reflex (often slow in horses, need abright light)
* Direct and consensual responses
* Occulomotor nerve (CN III)

Question 3

What does Anisocoria mean?

Answer 3

Difference in pupil size - issue with optic nerve

Question 4

What do the oculomotor, torchela and abducens nerves do?

Answer 4

• Oculomotor III - Motor to extrinsic muscles, ciliary body, levator palpebrae muscles
• Trochlear - Motor to extrinsic muscles
• Abducens - Motor to extrinsic muscles

Question 5

What nerves are involved in horizonal nystagmus and vertical nystagmus?

Answer 5

horizontal - III and VI
vertical - II and IV

Question 6

How do you test the trigeminal nerve in a horse?

Answer 6

Palpebral response (blink)
and touch the face for sensation

Question 7

What are the signs of facial nerve deficiencies in a horse?

Answer 7

Ptosis
asymmetry of face
muzle deviation away from the side of paralysis

Question 8

How do you test the vestibulocochlear nerve in the horse?

Answer 8

response to loud noise,
precence of a head tilt,
nystagmus

Question 9

How do you test the glossopharngeal nerve in a horse?

Answer 9

• Sensory, taste (posterior 1/3)
• Motor to tongue (extrinsic muscle)
  
  • Stylopharyngeus
• Motor to pharynx

Question 10

How do you test the accessory spinal nerve in the horse?

Answer 10

can the horse bend and control the neck

Question 11

How do you test the hypoglossal nerve inthe horse?

Answer 11

Intrinsic muscles of tongue and Pharynx
- can the horse swallow and eat

Question 12

How can you test the spinal refelxes of the horse?

Answer 12

• The cutaneous trunci reflex (CTR) is a reflex that causes a skin twitch when the skin is stimulated.
• Anal reflex
• tail tone
• Tail pull - will contract quadiceps

Question 13

What scale is used to describe ataxia in the horse? describe the grades?

Answer 13

The Mayhew ataxia scale:

Grade 1 – abnormalities are not consistent, present in only one part of the neurological examination
Grade 2 – abnormalities are consistent in all parts of the neurological examination but are mild
Grade 3 – abnormalities are consistent and moderate in all parts of the neurological exam, exacerbation may not be indicated!
Grade 4 – Truncal sway is evident when the horse is stood still, signs at walk are likely severe
Grade 5 – The horse is recumbent and unable to stand

Question 14

How do you assess the gait of a possibly ataxic horse?

Answer 14

• Walk in straight line (symemetry of one step to the next)
• Turn in tight circles
• Blindfold (only if below grade 3)
• walk up gradient
• Obstacles

Question 15

What diagnostic testing can you do for an ataxic horse?

Answer 15

• Haematology, biochemistry and acute phase proteins
• Differentiate infectious or inflammatory conditions (Increased WBC count, increased serum amyloid A, increased fibrinogen)
  Serologies for specific infectious diseases
• Cerebrospinal fluid analysis
• Endoscopy – guttural pouches
• Radiography (and myelography)
• Computed tomography (and myelography)

Question 16

Where do you sample CSF in the horse?
What are some things you are looking for?

Answer 16

Sites for sampling: AO (under GA), C1-C2 (standing with US) or LS (standing, blind)

• Acute haemorhhage - Immediately following trauma
• Xanthochromia (yellow colour) - Breakdown products of red cells
• Increased cellularity - White cell count

Question 17

What are they signs of gutteral pouch disease causing crainal nerve signs?

Answer 17

Ptosis, muzzle deviation, head tilt, head shaking, ataxia

Question 18

When is radiography of the neck indicated?

Answer 18

Indicated in all cases of bilateral and quadrilateral ataxia

Question 19

How is CT used for equine ataxia?
what are the dissadvantages and how are these overcome?

Answer 19

• CT of the Head - Standing sedated procedure – no GA risk
• CT of the neck - requires GA, Addition of contrast allows identification of spinal cord compression, but can’t detect dynamic lesions therefore need to do Flexed radiographic myelogram after CT (in recovery box)

Both are gold standard over radiographs

Question 20

what are the significant findings of a Flexed radiographic myelogram?

Answer 20

50% reduction in dorsal dye column or 25% reduction in dural diameter