L1 Cerebellum Disorders Flashcards
Function of normal motor system
Voluntary movements, facilitated by motor plan from cortex, delivered by LMN and sensory input
Function of cerebellum
- integrates sensory and other inputs from multiple regions of cortex and four spinal cord pathways
- (Inferior olivary nucleus) Compares the efferent and afferent copies to calculate motor error, and sends those errors back, updating the motor plan
Efferent copy of information
copy of motor plan from M1
Afferent copy
sensory info relaying what happened in periphery during task
Cerebellum uses info that it receives to…
- smoothly coordinate ongoing movements
- coordinate the sequencing of voluntary muscle contraction
- contribute to motor planning
- contribute to motor learning
- contribute to language, decision making, affect
Peduncles
are how info travels in and out of cerebellum
Lateral hemisphere of cerebellum
helps with motor planning for extremities
influences the lateral corticospinal tract
Intermediate hemisphere of cerebellum
function: distal limb coordination
influences lateral corticospinal tract, rubrospinal tract
Vermis and Flocculonodular lobe
function: proximal limb and trunk coordination. balance and VOR
influences anterior corticospinal tract, reticulospinal tract, vestibulospinal tract, tectospinal tract, MLF
Lateral motor systems
lateral corticospinal tract
rubrospinal tract
Medial Motor Systems
anterior corticospinal tract
reticulospinal tract
M/L vestibulospinal tract
tectospinal tract
impacted by vermis and flocc. nodules
Cerebellar Dysfunction
causes ataxia or a lack of order
movements have abnormal timing, trajectories through space
Ataxia
disordered contractions of agonist and antagonist muscles and resulting lack of coordination between movements at different joints seen in patients with cerebellar dysfunction
Dysmetria
abnormal trajectories through space. Undershoot or overshoot
Dysrhythmia
abnormal timing and rhythm of movements
Lateral lesions
present with ipsilateral deficits
Lesions of vermis
have bilateral deficits
Truncal ataxia
lesions affecting the cerebellar vermis primarily affect the medial motor systems
results in drunk like gait
Appendicular ataxia
lesions affecting the intermediate and lateral cerebellar regions affect the lateral motor systems
Sensory ataxia
damage to the lateral columns leading to a lack of peripheral proprioceptive input
improves with visual feedback
Dysdiadochokinesia
abnormalities of rapid alternating movements
Postural tremor
tremor seen when the limb muscles are activated to hold a particular position
Essential tremor
low amplitude postural tremor
Action or intention tremor
appendicular ataxia during movements toward a target
Ocular dysmetria
overshoot or undershoot of the target during saccades
Nystagmus
rhythmic beating that can change direction, occasionally upbeating with cerebellar dysfunction
Cerebellar S/S: Eye
Ocular Dysmetria
Nystagmus
inability to suppress VOR
Cerebellar Tremors
postural
essential
action or intention
Cerebellar S/S Speech
-speech has ataxic quality with fluctuations in rate and volume
-speech may be slurred and difficult to understand
Possible pathologies for Cerebellar disorders
Developmental
Metabolic
Progressive Degenerative
Trauma
Stroke
Tumor
Friedrich’s Ataxia
(progressive degenerative)
-no medical cure
-most common autosomal recessive disease
-results in deficiency of frataxin
-onset is at 15 yo
-life expectancy is 37.5 yo
Results of frataxin deficiency
-lesions in DRG, causing peripheral neuropathy
-dentate nuclei
-reduction in SC diameter, especially in DCML in spinocerebellar tracts
-impacts on CV and endocrine systems
CP of Friedrich’s Ataxia
-hallmark feature is ataxia
-peripheral neuropathy
-absent LE reflexes
-reduction of proprioception and vibration sense
-LE weakness and pes cavus
-DM
-VO impairments
-cardiomyopathy
Ataxia is usually…
ipsilateral to side of a cerebellar lesion
this is because pathways from cerebellum are double crossed
Crossings of lateral motor pathways
First = cerebellar outputs exit in decussation of superior cerebellar peduncle in midbrain
Second = corticospinal and rubrospinal tracts descend in the SC at the pyramids
Lesions of lateral and intermediate hemispheres case
S/S of proximal and distal limbs, including ataxia, intention tremor, dysdiadochokinesia
Midline lesions of cerebellar vermis or Flocculonodular lobes causes…
unsteady gait due to truncal ataxia and vestibulooccular dysfunction
does not cause unilateral deficits b/c medial motor systems influence trunk bilaterally
eye movements abnormalities and intense vertigo, nausea, vomiting due to connection to flocculonodular lobe
Eye patching of impaired eye
gives it a rest and prevents fatigue and double vision
Eye patching of non-impaired eye
to allow weaker eye an opportunity to work without the distraction of double vision
Impairment Examination includes
appendicular ataxia
truncal ataxia
vestibular tests
oculomotor tests
Appendicular Ataxia Exam
finger to nose
heel to shin
rapid alternating movements
toe tapping
finger tapping
indicates that proprioception is intact
Truncal Ataxia Exam
Tandem Gait
Romberg Test (not the best)
Titubation
Normal Gait
Titubation
rhythmic tremor mainly of the head and/or upper trunk with a frequency of 3-4 cycles/second
seen in any position or during activities
Gait in cerebellar dysfunction
Wide-based, unsteady gait
tandem gait will fall toward side of lesion
Saccades for cerebellum
abnormal with present of undershoot or overshoot
smooth pursuit would be abnormal with the presence of saccadic intrusions
Nystagmus cerebellum results
might be present and would likely be direction changing
Dorsal Column Lesion
visual feedback will improve ataxia
no dizziness, vertigo, nausea
loss of proprioception/touch
Lacunar Stroke
can lead to ataxia hemiparesis syndrome
combo of unilateral UMN signs and ataxia of same side
Scale for the assessment and rating of ataxia (SARA)
8 item performance based scale, yielding a total score of 0 (no ataxia) to 40 (most severe)
patient performs gait, stance, sitting, speech, finger chase, nose to finger, fast alternating hand movements, heel shin slide
Cueing/Facilitation for Cerebellar Involvement
Use tactile, verbal, visual cues, fading over time
use extrinsic cueing
practice should be random, whole, and high repetition
DOs of Cerebellar Ataxia Treatment
-proximal stability when necessary
-start with lower degrees of freedom
-external cues
-high repetition practice
-progress to targeting distal accuracy
-compensatory strategies are OK
DONTs of Cerebellar Ataxia Treatment
-start with work on distal accuracy
-weight the limb for increased proprioceptive feedback
-randomize practice
-emphasize strength training (most have normal strength, but not good motor control)
