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Neurology > Principles of vestibular disease and cerebellar disease > Flashcards

Principles of vestibular disease and cerebellar disease Flashcards

1
Q

What is ataxia?

A

A neurological sign consisting of gross incoordination of muscle movements, and is an aspecific clinical manifestation.

Can see less ataxia when walking quicker - run animal at different paces

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2
Q

What are the three types of ataxia?

A
  • Sensory ataxia
  • Vestibular ataxia
  • Cerebellar ataxia
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3
Q

What are the questions to ask regarding looking at animal with potential ataxia?

A
  1. How are the limbs moving?
  2. What about the head?
  3. How is the trunk moving during locomotion?
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4
Q

What is hypometria?

A

Shorter protraction phase of gait (stride)

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5
Q

What is hypermetria?

A

Longer protraction phase of gait (stride)

high stepping gait

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6
Q

What is dysmetria?

A

Combo of hypometria and hypermetria

Inability to control the distance, power, speed of action

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7
Q

What are the general proprioceptive pathways?

A
  • Peripheral nerve
  • Dorsal root
  • Spinal cord
  • Brainstem
  • Forebrain
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8
Q

What are the clinical signs of sensory ataxia?

A
  • Abnormal postural reactions

- Limb paresis (inability to create movement)

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9
Q

What are three areas where a lesion can cause vestibular ataxia?

A

In the vestibular apparatus -

  1. vestibular nuclei (central)
  2. vestibular portion of VIII
  3. vestibular receptors (peripheral)
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10
Q

What are the clinical signs of vestibular ataxia?

A
  • Head tilt (to side of lesion)
  • Leaning, falling or rolling to one side
  • Abnormal nystagmus
  • Positional strabismus
  • Normal (peripheral) or abnormal (central) postural reactions
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11
Q

What is the function of the Cerebellum?

A
  • fine tunes movement

- stops over-reach - no counter regulation = tremors

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12
Q

What are the clinical signs of cerebellar ataxia?

A

Wide based stance ** - over reaching

  • Intention tremors of the head
  • Loss of balance and truncal sway
  • Delayed onset and dysmetric hopping
  • Ipsilateral menace deficits with normal vision
  • No limb paresis or conscious proprioception deficits
  • Pendular nystagmus

Not as much lateralisation

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13
Q

What part of the nervous system has a direct inhibitory effect on the vestibular nuclei?

A

Cerebellum

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14
Q

In the neuro-exam

a) what can you observe?
b) what would you exam by testing hands-on?

A 
a) 
Mental status/behaviour
Postures
Gait
Abnormal involuntary behaviour
b) 
Posture reaction
Cranial nerves
spinal reflexes, muscle tone and size
sensory examination
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15
Q

What head positions indicate vestibular disease?

A
  • Head tilt: rotation of the median plane of the head (one ear lower than the other)
  • if on the left - muscle tone increases on that side

-Head turn: nose turned to one side, median plane of head is perpendicular to the ground

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16
Q

In which breeds is a pendular nystagmus a congenital abnormality?

A

Siamese
Birman
Himalayan

17
Q

In what diseases is pendular nystagmus present?

A

Cerebellar disorders and visual deficits

18
Q

What are the types of nystagmus can be seen in vestibular disease?

A
  1. Pendular nystagmus

2. Jerk nystagmus - horizontal, vertical, rotatory

19
Q

What is positional strabismus?

A

One eye drops down when head lifts up

20
Q

What is Horner’s syndrome?

A

Loss of sympathetic innervation to the eye

  • Enopthalmos
  • Third eyelid protrusion
  • Ptosis (drooping eyelid)
  • Miosis (small pupil - smooth muscle)
  • (congested vessels) - increase temp of eye on side of lesion
21
Q

What is the additional sign seen in horses with Horner’s syndrome?

A

They sweat on the ipsilateral side of the lesion

Nasal and conjunctival hyperaemia

22
Q

How does sweating give an indication of location of the lesion?

A

Regional sweating patterns helps indicate which nerves are affected and where the lesion is

23
Q

What clinical signs are seen in central vestibular disease?

A
  • Paresis possible
  • Conscious proprioceptive deficits possible
  • May be normal, obtunded, stuporous, comatose
  • Cranial nerves V-XII may be affected
  • Horner’s syndrome rare
  • Horizontal, rotary, and vertical nystagmus present
  • Nystagmus will change with head position
24
Q

What clinical signs are seen in peripheral vestibular disease?

A
  • NO paresis*
  • NO conscious proprioceptive deficits*
  • Can be alert or disorientated
  • ONLY Cranial VII nerve deficit
  • Horner’s syndrome possible
  • Horizontal and rotary nystagmus present (NOT vertical nystagmus)
  • NO nystagmus changes with head position
25
Q

What nerve is commonly affected in Horner’s syndrome?

A

CN 7 - tymphanic bulla inflammed - affects nerve and symphathetic stim

26
Q

What is myringotomy and how does this help in peripheral vestibular disease?

A

It’s a surgical procedure, puncturing the tympanic membrane

  • helps both relieve pressure in mid ear
  • can culture - see fluid or masses = if BAC - ddx for otitis media but if no bac - polyps, tumour, trauma
  • flush away debris/exudate
27
Q

What are the clinical signs with bilateral vestibular disease?

A
  • No nystagmus
  • No occulovestibular response
  • Head sways from left to right (exaggerated head movement)
28
Q

What is the role of the vestibulo-cerebellum?

A

Maintenance of equilibrium

29
Q

What is the role of the spino-cerebellum?

A

Regulation of muscle tone (to preserve normal position at rest/movement)

30
Q

What is the role of the cerebro-cerebellum?

A

Coordination of movement

31
Q

What is paradoxical vestibular disease?

A

Vestibular disease but the conscious proprioceptive deficits occur on the side OPPOSITE the head tilt
The vestibular lesion occurs between the cerebellum and the vestibular nucleus in this case, causing an increased output to the extensor muscle on that side

Not v common and handle carefully - feel nauseous

32
Q

What is the pathway that is affected in vestibular disease and how is it different in the central form and the paradoxical form?

A

Cerebellum —> V nuclei —–> extensor muscle
a) Central:
C—–> V Nuclei –X–> extensor muscle
b) Paradoxical
C–X–> V Nuclei —-> extensor muscle
Increased output to E muscle on the side of lesion - lose inhibition to the nuclei from cerebellum on this side!
Less on the other side

33
Q

What is cerebellar syndrome?

A
  • Spastic, dys- or hyper-metric ataxia
  • Intention tremor
  • Ipsilateral menace deficit and normal vision
  • Broad based stance
  • Postural reactions delayed with exaggerated responses
  • May or may not see anisocoria (pupil dilated contralateral to side of lesion)
  • Rarely see opisthotonus
  • May or may not see vestibular signs

Neurology (13 decks)

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