Principles of Vestibular and Cerebellar Disease Flashcards
(37 cards)
Define ataxia…
A neurological sign of gross incoordination of muscle movements.
What are the three types of ataxia?
Sensory
Vestibular
Cerebellar
Define hypometria, hypermetria and dysmetria…
Hypometria - Shorter protraction phase of gait
Hypermetria - Longer protraction phase of gait
Dysmetria - Ability to control the distance, power and speed of an action is impaired, combination of hypo- and hypermetria
What parts of the nervous system make up the proprioceptive pathways?
Peripheral never Dorsal root Spinal cord Brainstem Forebrain
What are the clinical signs of sensory ataxia?
Abnormal postural reactions
Limb paresis
What makes up the vestibular apparatus? What is it’s role in the body?
Vestibular nuclei
Vestibular portion of VIII
Vestibular receptors
Controls balance between extensor and flexor muscles
What are the clinical signs of vestibular ataxia?
Head tilt Leaning, falling or rolling to one side Abnormal nystagmus Positional stabismus Normal/abnormal postural reactions
What are the clinical signs of cerebellar ataxia?
Wide-based stance
Intention tremors of the head
Loss of balance and truncal sway
Delayed onset dysmetric hopping
Ipsilateral menace deficits with normal vision
No limb paresis or conscious proprioception deficits
Pendular nystagmus
What is assessed in the observation portion of the neuro exam?
Mentation
Posture
Gait
Abnormal involuntary movements
What is assessed in the hands-in portion of the neuro exam?
Postural reactions
Cranial nerves
Spinal reflexes, muscle tone and size
Sensory evaluation
Where is the peripheral vestibular system location?
In the ear canal
What reflex tests the vestibular system?
The occulovestibular reflex - flicking of the eyeline when the head is turned in different directions
What part of the vestibular system assess:
- Head motion and acceleration
- Head position and gravity
Where is the information from these and sensory inputs coordinated?
- Semi circular canals
- Saccule and urticule
Vestibular nuclei
How is information from the vestibular system outputted?
Forebrain, perceived orientation
SC and cerebellum
Oculomotor system, eye movements
What can input information to the vestibular nuclei?
Semicircular canals Saccule and utricule Cerebellum (inhibitory) Spinal cord Pontine reticular formation Contralateral vestibular nuclei
How do head turns and tilts differ?
Turn - median plane of the head, nose turned to one side (forebrain)
Tilt - rotation of the median plane of the head, one ear is lower than the other (vestibular)
Which breeds suffer from physiological nystagmus? What can cause pendular nystagmus? How does it differ from jerk nystagmus?
Siamese, Birman and Himalayan
Congenital abnormality or cerebellar disorders and visual deficits
Has no slow or fast phase
What are the clinical signs of Horner’s syndrome?
Enophthalmos (retraction of eyeball into orbit) 3rd eyelid protrusion Ptosis (drooping of upper eyelid) Miosis (constriction of pupil) Congested vessels
What is an additional clinical sign of Horner’s in the horse and why?
Sweating - have different innervation of the sweat glands
Which neural pathway is affected in Horner’s syndrome?
The sympathetic trunk of the autonomic system
How can regional sweating patterns aid localisation of neural lesions in horses?
The lesion will be cranial to innervation of the area that is sweating
What clinical signs differentiate central from peripheral disease?
Proprioceptive deficits - Central (Possible), Peripheral (No)
Consciousness - Central (Any), Peripheral (Alert)
CN deficits - Central (V-XII may be affected), Peripheral (VII only)
Vertical nystagmus - Central (Yes), Peripheral (No)
What are the clinical signs of bilateral vestibular disease?
No nystagmus
No occulovestibular response
Head swaying from L to R
What are the inputs to the cerebellum?
Visual
Auditory
Vestibular
