Neurological exam - LA (equine) Flashcards Preview

Neurology > Neurological exam - LA (equine) > Flashcards

Flashcards in Neurological exam - LA (equine) Deck (42):
1

Approaches - 2

- systematic approach e.g. tests of unconscious proprioception
- anatomic approach - most appropriate for horses/ large animals

2

Distinguish white/ grey matter

WHITE: myelinated axons
GREY: unmyelinated cells and bodies of the axons
- Opposite organisation in brain vs. spinal cord

3

Important aspects of hx to obtain

- did horse look/act clumsy before it was found down?
- any evidence of respiratory dz on property?
- any other horses?
- descriptions of behavioural abnormalities
- client video

4

What does excessive yawning indicate?

forebrain disease (unknown why)

5

What does abnormal behaviour indicate?

= forebrain disease
- e.g. circling, hyperaesthesia, head turn, odd postures

6

What does the cerebellum conrol?

- ascending proprioceptive pathways
- descending motor pathways

7

CS associated with cerebellar dysfunction - 4

- spastic or exaggerated movements
- absence/ diminished menace response
- intention tremor (worse when horse doing something)
- ataxia without weakness

8

Brainstem contents ---

- pons and medulla
- reticular formation
- ascending proprioceptive pathways
- descending motor pathways (--> weakness)
- CN nuclei
* when you find dysfunction of these modalities together, think brainstem *

9

What does ataxia, paresis and CN deficits together suggest?

brainstem disease

10

What does a wonky muzzle indicate?

left sided facial nn paralysis

11

Outline PLR

= true reflex
- afferent limb is in optic nn (CN 2)
- efferent is parasumpathetic fibres that run in the oculomotor nn (3) to constrict the pupil
- direct and consensual/ contralateral response. The latter is difficult to assess in horses so as long as you get good direct PLRs in each eye, then don't worry

12

What does the menace response test?

= requires perception of stimulus
- optic nerve
- optic chiasm
- thalamus
- opposite occipital cortex (but an unconscious event)
- facial nn and nucleus
- (cerebellum)

13

How is vision best tested?

- walk horse around / between obstacles
- fundic exam
- afferent limb of menace response

14

Control of eye position

- oculomotor nn (3)
- trochlear nn (4)
- abducens nn (6)

15

Frequency of strabismus as a CS

uncommon in UK, more common in USA.

16

Method - retractor oculi reflex

= press on cornea through the eyelid, feel for reflex retraction of the globe
- afferent: trigeminal (5) - sensory
- efferent: abducens (6) - motor

17

Lesions in the facial nn (7) are often accompanied by lesions where?

vestibular nn (CN 8) due to anatomical location

18

How do you determine central vs peripheral vestibular disease?

- difficult
- type of nystagmus?
- weakness?
- other CN involved?
- further testing

19

What type of nystagmus does central disease cause?

any type of nystagmus

20

What type of nystagmus does peripheral disease cause?

horizontal nystagmus

21

How does fast phase nystagmus help localise a lesion?

fast phase is away from the site of the lesion

22

What is physiological nystagmus?

changing what you are focusing on

23

How to assess pharyngeal and laryngeal function?

- swallowing
- vocalisation
- slap test (tests intrinsice laryngeal mm function)
* endoscopy *

24

What does eluphenazine toxicity cause? tx?

- causes extrapyrimidal system defects.
- Tx with diphenhydramine
- (n.b. eluphenazine is a drug used to calm horses)

25

Describe Horner's syndrome

= interruption of sympathetic nn pathway between hypothalamus and eye
- Ptosis (examine eyelashes closely - normal horse they point out, with horner's they point down)
- Miosis
- Enopthalmus
- Prominent TE
- conjunctival and nasal hyperemia
- sweating

26

Why do Horner syndrome horses sweat?

when SNS supply to skin is interrupted (this is normally autonomically controlled), horses BVs vasodilate and horses are prone to increased sweat production with vasodilation

27

Why might you get sweating over the mid and caudal neck?

controlled by vertebral nn (C2)

28

Define ataxia

a function deficit associated with defective proprioception

29

CS - ataxia

- hypermetria (exaggerated movements)
- hypometria (reduced movements)
- dysmetria
- truncal sway (back end doesn't follow front end)

30

T/F: assymmetric spinal cord lesions can produce signs similar to certain lamenesses

True

31

What is ataxia generally associated with?

irregular irregularities (i.e. a neurological problem)

32

What is lameness usually associated with?

a regularly irregular problem is usually an orthopaedic problem

33

T/F: bilateral pelvic limb suspensory desmitis and sacroiliac pain are common causes of unusual 'ataxia like' deficint...but usually the deficit is regular

True (despite orthopaedic problems usually tending to be a regularly irregular problem)

34

What are clues that a horse is truly ataxic? 2

- pacing (worse when head lifts up)
- circumduction

35

Possible origins or weakness - 2

systemic or neurological
- granulomatous enteritis --> IBD and PLE --> mm wastage
- equine motor neuron disease is a neurological problem

36

What type of tail pull is useful to assess a LMN or UMN weakness problem?

- LMN: standing tail pull
- UMN - walking tail pull

37

Features of UMN weakness - 3

- inability to control mm
- normal or increased tone
- no mm atrophy

38

Features of LMN weakness - 3

- inability to contract the mm
- flaccidity
- mm atrophy if chronic

39

Examples of lameness caused by mm disease

- post-exercise lameness
- exertional rhabdomyolysis (tying up)
- polysaccharide storage myopathy - genetic
- ischaemic myopathy - uncommon, associated with parasite migration, (aorto-iliac thrombosis)
- measure CK and AST

40

Tips for locating spinal lesions

- limb weakness can indicate local SC damage
- in a standing horse you can assume that spinal reflexes are intact
- most spinal reflexes are hard to assess in adult horses
- withdrawal reflexes are useful

41

Sacral and perineal signs

- perineal reflex
- sensation
- tail flaccidity
- rectal exam
- urinary incontinence

42

Name some classic cauda equina signs

- impaction in the rectum
- no perineal reflex