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Neurology > Neurological exam - LA (equine) > Flashcards

Neurological exam - LA (equine) Flashcards

1
Q

Approaches - 2

A
  • systematic approach e.g. tests of unconscious proprioception
  • anatomic approach - most appropriate for horses/ large animals
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2
Q

Distinguish white/ grey matter

A

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

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3
Q

Important aspects of hx to obtain

A
  • 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
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4
Q

What does excessive yawning indicate?

A

forebrain disease (unknown why)

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5
Q

What does abnormal behaviour indicate?

A

= forebrain disease

- e.g. circling, hyperaesthesia, head turn, odd postures

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6
Q

What does the cerebellum conrol?

A
  • ascending proprioceptive pathways

- descending motor pathways

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7
Q

CS associated with cerebellar dysfunction - 4

A
  • spastic or exaggerated movements
  • absence/ diminished menace response
  • intention tremor (worse when horse doing something)
  • ataxia without weakness
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8
Q

Brainstem contents —

A
  • pons and medulla
  • reticular formation
  • ascending proprioceptive pathways
  • descending motor pathways (–> weakness)
  • CN nuclei
  • when you find dysfunction of these modalities together, think brainstem *
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9
Q

What does ataxia, paresis and CN deficits together suggest?

A

brainstem disease

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10
Q

What does a wonky muzzle indicate?

A

left sided facial nn paralysis

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11
Q

Outline PLR

A

= 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
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12
Q

What does the menace response test?

A

= requires perception of stimulus

  • optic nerve
  • optic chiasm
  • thalamus
  • opposite occipital cortex (but an unconscious event)
  • facial nn and nucleus
  • (cerebellum)
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13
Q

How is vision best tested?

A
  • walk horse around / between obstacles
  • fundic exam
  • afferent limb of menace response
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14
Q

Control of eye position

A
  • oculomotor nn (3)
  • trochlear nn (4)
  • abducens nn (6)
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15
Q

Frequency of strabismus as a CS

A

uncommon in UK, more common in USA.

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16
Q

Method - retractor oculi reflex

A

= press on cornea through the eyelid, feel for reflex retraction of the globe

  • afferent: trigeminal (5) - sensory
  • efferent: abducens (6) - motor
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17
Q

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

A

vestibular nn (CN 8) due to anatomical location

18
Q

How do you determine central vs peripheral vestibular disease?

A
  • difficult
  • type of nystagmus?
  • weakness?
  • other CN involved?
  • further testing
19
Q

What type of nystagmus does central disease cause?

A

any type of nystagmus

20
Q

What type of nystagmus does peripheral disease cause?

A

horizontal nystagmus

21
Q

How does fast phase nystagmus help localise a lesion?

A

fast phase is away from the site of the lesion

22
Q

What is physiological nystagmus?

A

changing what you are focusing on

23
Q

How to assess pharyngeal and laryngeal function?

A
  • swallowing
  • vocalisation
  • slap test (tests intrinsice laryngeal mm function)
  • endoscopy *
24
Q

What does eluphenazine toxicity cause? tx?

A
  • causes extrapyrimidal system defects.
  • Tx with diphenhydramine
  • (n.b. eluphenazine is a drug used to calm horses)
25
Q

Describe Horner’s syndrome

A

= 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
Q

Why do Horner syndrome horses sweat?

A

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
Q

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

A

controlled by vertebral nn (C2)

28
Q

Define ataxia

A

a function deficit associated with defective proprioception

29
Q

CS - ataxia

A
  • hypermetria (exaggerated movements)
  • hypometria (reduced movements)
  • dysmetria
  • truncal sway (back end doesn’t follow front end)
30
Q

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

A

True

31
Q

What is ataxia generally associated with?

A

irregular irregularities (i.e. a neurological problem)

32
Q

What is lameness usually associated with?

A

a regularly irregular problem is usually an orthopaedic problem

33
Q

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

A

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

34
Q

What are clues that a horse is truly ataxic? 2

A
  • pacing (worse when head lifts up)

- circumduction

35
Q

Possible origins or weakness - 2

A

systemic or neurological

  • granulomatous enteritis –> IBD and PLE –> mm wastage
  • equine motor neuron disease is a neurological problem
36
Q

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

A
  • LMN: standing tail pull

- UMN - walking tail pull

37
Q

Features of UMN weakness - 3

A
  • inability to control mm
  • normal or increased tone
  • no mm atrophy
38
Q

Features of LMN weakness - 3

A
  • inability to contract the mm
  • flaccidity
  • mm atrophy if chronic
39
Q

Examples of lameness caused by mm disease

A
  • 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
Q

Tips for locating spinal lesions

A
  • 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
Q

Sacral and perineal signs

A
  • perineal reflex
  • sensation
  • tail flaccidity
  • rectal exam
  • urinary incontinence
42
Q

Name some classic cauda equina signs

A
  • impaction in the rectum

- no perineal reflex

Neurology (26 decks)

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