Ataxia: Cerebellar Dz Flashcards
(25 cards)
What may worsen sensory ataxia?
- loss of proprioception (slidy kennel)
- loss of vision (blindfold, dark room)
- reflection and darkenss not helpful
What are the 3 types of ataxia?
- sensory
- vestibular
- cerebellar
How is ataxia affected by gait?
EASIER TO RUN!!! cf. lameness which worsens with ^ gait
What aspects of the gait should you look for when assessing ataxia?
- limb movement
- head movement
- trunk movement
What is sensory ataxia also known as?
- spinal or proprioceptive
Define hypo and hypermetria
- shorter or longer protraction phase of gait
Define dysmetria
- ability to control distance, power and speed of an action (combination of hypo and hypermetria)
Give the 5 general proprioceptive pathways (-> sensory ataxia)
- peripheral nerves
- dorsal root
- spinal cord
- brainstem
- forebrain
What clinical signs are commonly seeen in combination with sensory ataxia?
- abnomal postural reactions
- limb paresis (looks like lameness)
What clinical sign may be seen with sciatica?
- arched back (relieves pressure on n. root)
- usually where pain is greatest
What is included in the vestibular apparatus?
- Vestibuular nuclei (central)
- Vestibular portion of VIII (vestibulocochlear n.)
- Vstibular receptors (peropheral)
Clinical signs of vestibular ataxia
- head tilt
- leaning, falling and rolling to one side
- abnormal nystagmus (slow phase TOWARDS lesion, fast run away from the lesion)
- positional strabismus
- normal (peripheral) or abnormal (central) postural reactions
Clinical signs of cerebellar ataxia
- wide based stance
- intention tremor (head)
- loss of balance and truncal sway
- delayed onset and hypermetric hopping
- ipsilateral menace deficits with normal vision
- no limb paresis or conscious proprioception deficits
- pendular nystagmus
What is the difference between concious and unconcious proprioception?
- conscious can be over ridden eg. foot placement
- unconcious cannot be overridden eg. hopping test
Where are movement impulses initiated?
Forebrain??? then modulated by cerebellum
What disease are arabians affected by?
(rarely)
- cerebellar disease
Outline the neurological exam in the correct order
> observation - mental status and behaviour - posture - gait - ID abnormal involuntary movements > hands on - postural reaction testing - cranial nerve assessmenet - spinal reflexes, muscle tone and size - sensory evaluation
What is the peropheral vestibular system composed of?
vestibular apparatus =
- central vestibular nuclei
- vestibular portion of VIII
- peripheral vestibular receptors
How are the vestibular hair cells different to other cells in the body?
- K+ depolarises
- same for insulin secretion int he pancreas
- all other cells depolarised by Na
What is the vestibular organ composed of?
- otolith organs (utricle and saccule) contain vestibular hair cells
- 3 semicircular canals, within which the ampullae contain vestibular hair cells
- sensory epithelium = macula, hair cells, stereocilia, gelatinous layer, fibrous otolithic membrane embedded with otoconia (ca co3 crystals)
Common sign of ataxia
Crossing legs
What is the occulovestibular reflex?
- inducing nystagmus by moving the head - fast phase should be towards the direction of movment, slow phase away (maintain focus on one point as head trns by inervatig contralateral ocular muscles excitatory and inhibiting ipsilateral ocular muscle)
What is the main output of the vestibular pathways to the body? What type of reflex is this?
- extensor muscles
- unilateral reflex
What tpes of movement are detected by the semicircular canals, saccule and utricle and visual/proprioceptive/tactile inputs? Where do all these signals go?
- head motion (angular acceleatio) - semicircular canasl
- head position (gravity) - saccle and utricle
> all go to the vestibular nuclei
> outputs: forebrain perceived orientation, SC and Cerebellar, occulomotor outputs
