Cerebellar Disorders Flashcards
what are 4 theories of cerebellar function?
1- comparator
2- compensator
3- feedforward control
4- motor learning
what is the comparator theory of cerebellar function?
error correcting mechanism
Sensory information from evolving movement and motor output are compared
if it doesn’t match the cerebellar will provide corrective feedback
what is the compensator theory of cerebellar function?
rather than providing corrections to ongoing movement the cerebellum is assumed to perform predictive compensatory modifications of reflexes in preparation for movement
what is feedforward control theory of cerebellar function?
programs or models of voluntary movement skills based on a memory of previous sensory input and motor output.
If the cerebellum is damaged movement is then graded by long delay sensor feedback loops through the cerebrum just as in learning a new skill and incoordination will result.
what is the motor learning theory of cerebellar function?
through trial and error and cognition
what does damage to the cerebellum cause?
The cerebellum is not necessary to basic elements of perception or movement.
Rather, damage to the cerebellum disrupts the spatial accuracy and temporal coordination of movement.
It impairs balance and reduces muscle tone.
It also markedly impairs motor learning and certain cognitive functions.
what is the flocculonodular lobe/vestibulocerebellum (archicerebellum)?
receives input directly from vestibular afferents (SCC and otolith) controlling balance and eye movements.
Disruption of these projections impair an individual’s ability to use vestibular information to control eye movements during head rotation and movements of the limbs and body during standing and walking.
what is the spinocerebelum (paleocerebellum)?
receives visual, auditory, and vestibular inputs as well as somatic sensory input from the head and proximal parts of the body
It functions to control proximal muscles of the body and limbs.
It governs posture and locomotion as well as gaze.
Pathways cross x2- ipsilateral deficits
what is the cerebrocerebellum (neocerebellum)?
its output is mediated by the dentate nucleus, which projects to motor, premotor and prefrontal cortices.
It is intimately involved in planning and menial rehearsal of complex motor actions and in the conscious assessment of movement errors.
Many motor acts are made up of multiple components, each of which is initiated before the preceding one is completed.
Lesions disrupt timing of various components, which appear to take place sequentially rather than being coordinated smoothly–> decomposition of movement
what are symptoms of cerebellar damage ?
hypotonia
-pendular reflexes
ataxia
- delay in initiating movement
- dysmetria- errors in the range of movement
- dysdiadochokinesia- can’t sustain a regular rhythm nor produce an even amount of force
- decomposition of movement- errors in the relative timing of the components of complex multi-joint movements
- intentional tremors
balance
-postural tremors and a delay in the automatic postural adjustments
gait disturbances- staggering gait resembling someone intoxicated
- decrease in arm swing
- can’t walk in straight line
- uneven step length
- increase or decrease BOS
- decrease rhythm of gait
- can’t adjust to changes in surface
speech- melodic quality of speech is changed- dysarthric
gaze evoked nystagmus
what are types of disorders to the cerebellum?
CVA
TBI
degeneration
tumors
when cerebellar testing, what are non equilibrium coordination tests?
alternate or reciprocal motion- the ability to quickly reverse movement from agonist to antagonist
finger to nose
finger to finger
alternate finger to nose, finger to finger
finger opposition
alternate supination/pronation
patting (hand)
tapping (foot)
heel to knee to toe (shin slides)
what is the loss of ability to alternate motion called ?
adiadochokinesia
what is impaired ability to alternate motion called?
dysdiadochokinesia
what is synergy of movement?
ability to perform movement achieved by muscle groups acting together
what is the loss of synergy of movement called?
asynergia
what is impaired synergy of movement called?
dyssynergia
what are tests for synergy of movement?
finger to nose finger to finger heel to knee to toe pointing past pointing throwing a ball kicking a ball walking
what is movement accuracy?
ability to judge distances and speeds of movement
what is the loss of movement accuracy called?
ametria
what is impaired movement accuracy called?
dysmetria
what are tests for movement accuracy?
finger to nose finger to finger heel to knee to toe pointing past pointing toe to examiner's finger drawing a circle making a figure 8 with foot
what is fixation or holding posture?
ability to hold a posture of individual parts of the body
UE: pt. holds both arms horizontally in front of him (first with eyes open then with eyes closed)
LE:
- supine- pt. raises one leg at a time, holds and lowers slowly (guard pt. for possible loss of control)
- LE- pt. holds knee extended
what are equilibrium coordination tests?
note any swaying or unsteadiness of posture during the following activities:
rising from a supine position to a sitting one w/out the use of one’s hands
rising from a sitting position to a standing position
standing, laterally flexing the trunk to each side
standing, bending forward and returning to the upright position
standing, slightly extending the head and trunk
walking, placing the heel or one foot directly in front of the toe of the opposite foot
walking along a straight line
walking sideways (braiding)
stopping and starting abruptly while walking
climbing stairs
mexican hat dance
assess activities for unilateral, ipsilateral, contralateral, bilateral symmetrical, B asymmetrical, B unrelated (UEs and LEs performing dissimilar activities simultaneously) and 4 limb activities
