LA Neuro Exam Flashcards
(38 cards)
What does a dropped elbow indicate in horses?
- radial n. damage and paralysis
- d/t scapula avulsion on brachial plexus with trauma
Where does white and grey matter lie within the brain and spinal cord?
> Spinal cord
- white matter outside, grey inside
Brain
- grey matter outside, white inside
What is grey and white matter/
- white = myelinated axons
- grey = cell bodies
What clues int he history may help with your dx?
- horse looking or acting clumsy before being found down?
- respiratoy disease?
- other horses involved?
- behavioural abnormlaities/video
What clues in the PE may help with your dx?
- non-neuro reason?
- icteric hore with depression indicating 1* liver/systemic problem
- lameness eg. foot abscess?
What is a radiculopathy?
- trapped nerve base of neck leads to problems only when neck is in flexion (eg. with long reins)
How can forebrain function be assessed?
> mentation - bright or depressed, responsive ?
> behaviour - bizarre circling, hyperaesthesia, head TURN, odd postures, reversing
Where do seizures occour?
FOREBRAIN
Is cerebellar dz common in horses ?
No v rare cf. smallies
- BUT high level well bred dressage horses with high floating gate show some abnormalities of the spinal canal that may indicate spinal compression causing the hypermetria - interesting. nb. this is not cerebellar dz/
What cranial nerve response is affected by cerebellar disease?
Menace absent or dimished
Is weakness seen with cerebellar disease?
NO
What inherited condition is present in arabs?
cerebellar abiotrophy
- v rare still
What structures are present int he brainstem? What clinical relevance is this?
- pons and medulla
- reticular formation (controls levels of consciousness)
- ascending propriceptive and descending upper motor neuron pathways
- cranial nerve nuclei
> dysfunction of a combination of these modalities - suspect brainstem, including - altered levels of conciousness
- weakness (shuffly gait) and ataxia
- CN deficits
How are acute brainstem lesions gained in horses?
- fx basioccipital and basiethmoid?? bone underlying brainstem when they rear and fall backwards
- > heamatoma and haemorrhage into the GPs
What is the afferent and efferent limbs of the PLR?
- afferent optic 2
- efferent parasympathetic fibres of occulomotor 3
Pathway of menace?
- optic nerve
- optic chiasm
- thalamus
- OPPOSITE occipital cortex
- facial n. and nucleus
- cerebellum
> FOREBRAIN INVOLVED
Which species have the highest proportion of decussation at the optic chiasm?
- prey species d/t no need for binocular vision (85% cf. predators 50%)
How is vision best assessed?
- walk around obstacles
- fundic exam
- menace (afferent limb)
Which nerves control occular position?
III, IV, VI
afferent and efferent limbs of the retractor oculi reflex?
press on cornea through eyelid + feel for retraction
- afferent trigem V
- efferent aducens VI
What does trigem 5 provide?
- sensory to majority of face
- motor mm. of astication (masseter and temporalis mm.)
Which cranial nerves are often affected together?
facial VII and vestibular VIII d/t anatomical location
Which way do head tilts go wrt the lesion?
TOWARDS the lesion d/t loss of innervation of extensor muscles ?? LOOK UP
How can central and peropheral vestibular dz be differentiated?
- type of nystagmus (central anything and can change, peripheral always HORIZONTAL)
- weakness
- other CNs involved
