Cerebellar Disorders Flashcards
what are 6 cerebellar functions
- coordinate range, velocity, and strength of ms contractions to produce steady, volitional mvmts and postures
- equilibrium in conjunction w vestib and sensory systems
- ms tone regulation
- eye-head coordination
- coordinating ms for speech production
- error-based motor learning and adaptation
what is the cerebellum’s role in error-based motor learning and adaptation
implicit memories and procedural memories
- feed forward (ex: how to ride a bike)
describe the cerebellum’s process for complex computations
takes in sensory inputs and compares to environment, to visual input, to vestib input, and intended motor plan
-> then makes real time adjustments to maintain balance and have smooth motor patterns
how does the cerebellum communicate with other regions of the brain
3 main, large axonal bundles running through peduncles
what is the role of deep cerebellar nuclei
send efferent signals and adjustments to motor mvmts
what are the 3 pairs of deep cerebellar nuclei
fastigial
interposed
dentate
what are the 3 functional zones
spinocerebellar
cerebrocerebellar
vestibulocerebellar
what functional zones are the 3 deep cerebellar nuclei located in
fastigial & interposed = spino
dentate = cerebro
what is the general function of fastigial and interposed nuclei
motor execution
where is the fastigial nuclei located specifically
in vermis of spinocerebellums
where does fastigial nuclei receive signals from
vermis and cerebellar afferents which carry vestib, prox somatosensory (trunk & postural ms), auditory, & visual info
- aka medial descending systems
where are efferents from fastigial nuclei sent
vestib nuclei and reticular formation
what are the functions of the fastigial nuclei and what is the main one (4)
postural ms tone **
upright postural control
locomotion
gaze and eye mvmts
what are 5 s/sx of a lesion to the fastigial nuclei
poor balance
ataxic gait
- truncal ataxia/instability
falls
hypotonia
oculomotor deficits
what nuclei compose the interposed nuclei and where are they located
emboliform and globose nuclei
lateral spinocerebellum
what can truncal ataxia manifest as
instability
rocking back and forth
where does the interposed nuclei receive signals from
spinocerebellar tract, prox somatosensory, (limbs and periphery), auditory and visual pathways
- aka lateral descending systems
where are efferents from interposed nuclei sent
red nucleus of rubrospinal tract
what are the functions of the interposed nuclei (2)
control agonist-antagonist firing
coordinated limb mvmts
what are 7 s/sx of a lesion on the interposed nuclei
imbalance
ataxic gait
intention tremor
rebound phenomenon
dysdiadochokinesia
dysmetria
dysarthria
where does the dentate nuclei receive afferent inputs from
cerebral cortex (motor, premotor, prefrontal, sensory, visual, auditory cortices) via pontine nuclei
- aka areas 4 & 6
where are efferent signals sent from the dentate nuclei
red nucleus and ventrolateral thalamic nucleus
what are the functions of the dentate nuclei (4) and what is the main one
motor planning**
complex, multi joint mvmt
visually guided mvmt
sensorimotor error adjust
what are 5 s/sx of a lesion on the dentate nuclei
dysdiadochokinesia, dysmetria, dyssynergia (decomposition of mvmt), poor visuomotor coordination
where are vestibular nuclei located and what is consideration of this
in brainstem (medulla) so technically not cerebellar nuclei
where are signals to vestibulocerebellum received from
afferents from vestib and visual areas
where are efferent signals from vestibulocerebellum sent to
efferents to medial and lateral vestib nuclei (start of vestibulospinal pathways)
what are the functions of the vestibulocerebellum (4) and what are the main ones
posture and balance** control
coordinate eye** and head mvmt
VOR
gaze stability
what are 4 s/sx of a lesion on the vestibulocerebellum
ataxia w vertigo & nystagmus
unable use vestib info to control eye mvmts during head rotation (VOR)
poor coordinated mvmt of trunk and limbs in standing and w walking
imbalance and dec postural control
what is the function of the cerebellar peduncles
information super highways
- connects cerebellum to rest of brain
what is an important consideration in how the peduncles sit in relation to brain
form walls to 4th ventricle
- makes cerebellum vulnerable to changes in. ICP and hydrocephalus
what is the blood supply for the cerebellum and where does each go
SCA -> ant lobe
PICA -> post lobe
AICA -> vent ant and post lobes, flocculonodular lobe
all 3 arise from vertebrobasilar arteries
what is the most common blood supply syndrome of the cerebellum
PICA
- SCA and AICA are rare
how does the cytoarchitecture vary in the cerebellum and what are the 2 main components
fairly uniform
purkinje cells
climbing/mossy fibers
what is the role of purkinje cells
axons project to one of deep cerebellar nuclei
- carries output of cerebellar cortex
what is the general function of climbing and mossy fibers
modulate activity of purkinje cells
climbing vs mossy fibers
climbing
- produce large complex spikes in purkinje cells
- not modulated by sensory or motor activity
- more involved in feed forward programs
mossy
- synapse w granule cells then eventually purkinje cells
- highly modulated by sensory stim and motor activity (relay info like direction, velocity, duration, magnitude of mvmt and sensory stim)
- more involved w ongoing motor activity and making adjustments
what are non-motor cerebellar functions and what is responsible for this
memory, cog, attention, executive function, spatial cog
interconnections w pre-frontal cortex
what type of syndrome do you see more marked cog dysfunction
when post lobes of cerebellum are affected bilaterally (PICA infarct)
how do effects present for unilateral lesions and why
ipsilateral effects
d/t uncrossed or double crossing of efferents to cerebrum, vestib nuclei, and red nucleus
what are 7 common s/sx of cerebellar lesions
- ataxia (uncoordinated mvmt)
- dec balance and postural instability
- dysarthria
- nystagmus, vertigo, ocular motor dysfunction
- hypotonia
- n/v
- asthenia (generalized weakness)
what are 4 examples of hereditary etiology for cerebellar disorders
- autosomal dominant
- spinocerebellar ataxia
- episodic ataxia - autosomal recessive
- Friedrich’s ataxia - x-linked disorders
- mitochrondrial dz
- fragile-x syndrome - vit E deficiency -> poor cerebellar fxn
what are 5 acquired etiologies for cerebellar disorders
MS
CVA, TBI, brain tumor
toxicity - EtOH, heavy metal, drugs
infectious process
-> can cause abscesses or inflammation
idiopathic - slow degen
what is an autosomal dominant etiology for cerebellar disorders
spinocerebellar ataxia
what is an autosomal recessive etiology for cerebellar disorders
friedrich’s ataxia
what are x-linked etiologies for cerebellar disorders
mitochondrial dz
fragile-x syndrome
what is spinocerebellar ataxia characterized by
ataxia and dystonia, dysarthria, opthalmoplegia (extraocular eye ms), poor hand control, spasticity, neuropathy
how can effects of spinocerebellar ataxia present
purely cerebellar or extracerebellar effects (SC degen)
prognosis and course of dz for spinocerebellar ataxia
manifests 30-50s
normal to shortened lifespan
leads to cerebellar atrophy - slow progressing and no med intervention available
what is Friedrich’s ataxia
degen of SC, peripheral n., and cerebellum
-> more severe presentation than spinocerebellar atrophy
what are the first signs of Friedrich’s ataxia
ataxic gait
then UE and trunk involvement
what are 4 s/sx of Friedrich’s ataxia
loss of proprioception and vibration sense
- d/t peripheral n. and SC involvement
hyporefleia
dysarthria
(+) Babinski
what are 4 secondary complications is Friedrich’s ataxia associated with
cardiac abnormalities
hearing loss
vision loss
progressive MSK degen
course and prognosis of Friedrich’s ataxia
onset 5-15yo
wc bound w/i 10-20yo
shorter life span (may survive 60s-70s)
what is mitochondrial dz
lack of energy/power, results in weakness and neuro-degen w particular impacts on cells in cerebellum
what is the prominent clinical feature of mitochondrial dz
cerebellar ataxia
course of dz in mitrochrondrial dz
typical onset in young adulthood
progressive
what is fragile-x syndrome often a differential dx for
children showing signs of developmental delay
what is fragile-x syndrome? what will pts often have difficulty w and why
inherited form of intellectual disability
difficulty w motor learning, cog, and coordination
-> alterations in structure and plasticity of synapses on purkinje cells
what is ataxia w vitamin E deficiency (AVED) characterized by (6)
dysarthria
proprioceptive loss
loss of balance
titubation (involuntary mvmt of head)
dystonia
retinitis pigmentosa (pigment affected)
course of AVED and prognosis/treatment
manifests in late childhood -> early teens
many individuals wc bound if untreated
treatable w vit E supplementation
- can halt or improve sx
how common is a cerebellar artery stroke in general
very rare - 5%
what are 4 s/sx of a PICA stroke
vertigo
ataxia
nystagmus
unsteadiness
what are 4 s/sx of a SCA stroke
dysmetria of UE (ipsi)
unsteadiness
dysarthria
nystagmus
what are 3 s/sx of an AICA stroke (pons involvement)
dysmetria
vestib signs
facial sensory loss
what is a common sx of all cerebellar artery strokes and what is the concern w this
swelling
-> compression of 4th ventricle
—> hydrocephalus from obstructing CSF flow
what are 4 s/sx of edema and compression of the posterior fossa d/t a cerebellar artery stroke and what is the concern
- compromises respiratory centers in brainstem
- brainstem herniation
- CN VI palsy
- abnormal pupil reactions
can be lethal
how does cerebellar stroke treatment compare to cerebral strokes
very similar
why are there poorer prognoses w cerebellar strokes
rapid inc in pressure in area that isn’t forgiving
what are indications for poor prognoses in cerebellar strokes
damage to cerebellar nuclei and/or output pathways, superior cerebellar peduncles
SCA lesion, hemorrhagic, extracerebellar damage
what is the pathophys of EtOH toxicity which causes cerebellar dysfunction
alteration in GABA receptor dependent neurotransmission
- EtOH inc GABA release in purkinje cells and interneurons, inc tonic inhibition of interneurons, dec excitatory output of deep cerebellar nuclei
—> cerebellar dysfunction and ataxia
higher affinity for vermis and vermis is more vulnerable to changes
-> see more trunk and LE ataxia
how does EtOH create long term cerebellar dysfunction
EtOH induced cerebellar damage can persist even after complete abstinence d/t neuronal and mitochondrial damage
what component of the cerebellum is especially vulnerable to toxicity
purkinje cells
what is a common secondary complication of long term EtOH toxicity
thiamine deficiency
- wernicke’s encephalopathy
- korsakoff’s syndrome **
korsakoff common in EtOH abuse
- memory loss, ataxia, vision changes
what are other common toxicities other than EtOH which can lead to cerebellar disorders (7)
thiamine deficiency
anti-epileptics
amioderone
chemo
cocaine, heroin
environmental toxins
hyperthermia
what is multisystem atrophy (MSA)
sporadic neurodegen dz of undetermined etiology w adult onset
- death w/i 6-10yo
what are 2 main types of manifestations of MSA
autonomic dysfunction
motor dysfunction
can see neuropsych sx
what are 3 s/sx of autonomic dysfunction in MSA
GU dysfunction
- urinary retention, incontinence/constipation
ED
OH
what are s/sx of motor dysfunction in MSA
parkinsonism and/or cerebellar dysfxn
- gait ataxia
- dysarthria
- intention tremor
- oculomotor dysfunction
what are the 2 subtypes of MSA
MSA-P (predominant parkinsonism)
MSA-C (predominant cerebellar)
what is the treatment for MSA
levodopa
why do we check CN function in a PT exam for a cerebellar disorder
CN can be impacted by loss of communication w cerebellum
what are components of the BSF exam that are esp important in cerebellar disorders
coordination
- non-equilibrium tests (dysmetria, dyssynergia, dysdiadochokinesia, rebound, intention tremor)
- equilibrium tests
CN function
oculomotor function
- smooth pursuits, saccades
vestib screening tests: VOR, VORc
what are 8 non-equilibrium tests
finger to nose
finger to finger
finger opposition
forearm pron/sup
rebound test
heel to shin
drawing a circle
hand or feet tapping
what are 8 equilibrium/balance tests
standing w narrow BOS
perturbations
romberg
tandem stance & walk
walk on heels or toes
figure 8
start and stop on command
walk sideways, around obstacles
what is a dz specific standardized measure of ataxia
Friedrich ataxia rating scale
what are 3 standardized measures of ataxia and what does the literature say
ICARS - most detailed
SARA - excludes oculomotor
BARS - shortest, includes all domains
ICARS is preferred d/t high correlation w disability scale
what are 12 PT interventions for ataxia
PNF: RI, COI, SR
Frenkel exercises
mCIMT
endurance training
trunk stabilization/strengthening
axial and/or limb weighting
balance training
BWSTT and overground gait training
vestib habituation exercises
biofeedback
cooling
VR
when selecting a PT intervention for ataxia, what should you consider
nature of lesion
compensatory vs restorative strategies
how should PT interventions for ataxia be prescribed and progressed
work on specific and target mvmts
-» then inc speed
when is axial and/or limb weighting appropriate and why
great compensatory strategy
- will see deterioration if remove wt
when is biofeedback used as an intervention in ataxia
to get a more precise ms response
(don’t fully understand mechanism)
what are 3 strategies to improve function in someone w ataxia
- use external constraints to provide steadiness and enable practice of tasks otherwise too difficult
-> walking in parallel bars - practice actions involving production of rapid initial burst of agonist activity
-> jumping, jogging, throwing a ball - practice tasks that require predictive timing
-> hand eye coordination, bouncing a ball, hitting a baseball
what is a strategy to improve functional balance in ataxia
train everyday actions in standing w narrow BOS and no arm support
what are strategies to inc prox strength w low ms tone and truncal ataxia
pushups against wall for UE WB-ing
pulling activities w weighted objects or resistance
what are strategies to improve UE control in cerebellar disorders
UE exercises in sitting and standing
picking up and placing activities
start arms close to body -> progress by inc reaching distance
what are strategies to improve dynamic stability of trunk and limbs in cerebellar disorders
activities rely on balance control
- tandem walking
- walking in narrow spaces
- walking on different surfaces
gradually inc mvmt complexity/dual task and speed
what are strategies to improve intersegmental control and coordination in cerebellar disorders
WBing exercises for LE involving repetitive flex and ext over fixed feet
- repetitive STS
- repetitive squats
- step ups/down
- heel raises
vary wt resistance or body wt, additional wts in vests
what are strategies to provide practice controlling agonist/antagonist ms activity
performance of smooth mvmts
various amps and speeds
stopping and starting at various points in range and at various mvmt speeds
what are things to consider in creating practice environment which enables person to develop more control/accuracy during practice
support condition
timing constraints
environmental context
what are ataxia balance crutches
forearm crutches
maintain contact simultaneously
helps to prevent lateral displacement & sway
what is important to emphasize if PNF is used as an intervention in cerebellar disorders
emphasize timing of agonist/antagonist, strengthening
what are frenkel exercises and what does the literature say
AROM exercises, can help to improve coordination bc of focus on smoothness of mvtms
no evidence of benefits in literature
why does limb weighting work when it is on the patient
inc proprioceptive and spinocerebellar inputs that can help the cerebellum adjust mvmt and get better motor output
what outcomes were seen w limb weighting
short term improvement of performance but may cause worsening of sx when removed or not used
good compensatory method for short term use w ADLs
what does evidence say about axial weighting
encouraging findings, mechanism poorly understood
how does cooling work as a PT intervention
can dec cerebellar intention tremor
- via improved nerve conduction velocity, inc ms stiffness
what does the evidence say about the use of biofeedback (visual or auditory) in MS
improve gait parameters
- inc in gait speed and stride
when do you choose compensatory methods to dec cerebellar ataxia
degen or progressive conditions
early in rehab to promote safety and independence w functional tasks
what are compensatory strategies that can be used in cerebellar disorders (6)
use of visual/verbal cues
dec speed of mvmt
inc BOS - use of UE in sitting
weighting
cooling
AD for amb
when do you choose restorative approaches and promote recovery in cerebellar disorders
stable, non-progressive insults or lesions
what are restorative strategies that can be used in cerebellar disorders (8)
balance/equilibrium activities
frenkels
PNF
strength/endurance training
mCIMT
vestib retraining
VR
BWSTT and overground gait training
obstacle courses
- narrow paths, head turns, change directions
