Ataxia: Vestibular Dz Flashcards
How do the hairs detect yaw movement?
both sides affected oppositely when fluid flows and pushes hairs
What is the main output from the vestibular system?
Extensor muscles
- so if lost, extensor muscle tone lost
Outline angular acceleration head motion pathway
- semicircular canals
- vestibular nuclei
- forebrain… to compelte
gravity
-
K
visual
-
What other inputs are there to the vestibular nuclei?
- cerebellum: primarily INHIBITORY
- spinal cord
- pontine reticular formation
- contra-lateral vestibular nuclei
Which side is the lesion on with nystagmus?
SLOW phase (weak side)
What is pendular nystagmus? Which breeds are predisposed?
- siamese, burmese and himalayan
- congential abnormaltiy
(^ no. fibres cross chiasma) - cerebellar disorders and visual defects
- no slow phase
What is jerk nystagmus?
- horizontal, vertical or rotary
- ??
- What is searching nystagmus?
- blindness
What is positional strabismus?
- affected side doesnt realise head has moved up for eg. so eye stays looking down and eye rolls
What clinical signs are associated with Horner’s? Cause?
- loss of sympathetic innervation to the eye
- enopthalmus
- 3rd eyelid protrusion
- ptosis
- miosis
- congested vessels (hotter ear that side)
How does horner’s syndrom differ in horses?
- ptosis (look for eyelashes)
- miosis
- enopthalmus
- prominant TE
- conjnctival and nasal hyperaemia
- sweating
Where in the symathetic system is usually affected for horners?
LOOK UP (diagram on lecutre echo )
Outline regional sweating patterns in horses
If the lesion is cranial to where the sympathetic chain splits into the spinal nerves of the thoraco lumbar region and courses back up the neck as the sympathetic chain(?) then sweating will be observed alongthe length of the sympathetic interuption. If further along the sympathetic trunk then sweating will be more localised.
- horses ^ sweat d/t vasodilation and ^ adrenaline so if sympathetic innervation lost -> vasodilation and sweating.