Cerebellar Disorders Flashcards
Functions of the cerebellum:
To make movements of the extremities, trunk and eyes as smooth as possible by continually making small corrections.
How does the cerebellum achieve movements
Achieved through coordinated contraction/relaxation of agonist & antagonist muscles
Inputs to cerebellum come from which areas
sensory (proprioception) pathways from spinal cord, cortex, brainstem
How does motor information from cord get to cerebellum
–> ventral spino cerebellar tract —>superio rcerebellar peduncle–> cerebellum
Visual,sensory,motor information from cortex get to cerebellum how?
pontine nuclei–>middle cerebellar peduncle –>cerebellum
How does Proprioceptive information from limbs get to crebellum
–>fasiculus gracilis/cuneatus–> spinocerebellar tract and cuneo cerebellar tract –> interior cerebellar peduncle –>cerebellum
How does there cerebellum cause movement (the path)?
VL thalamus–> primary motor&supplementary motor cortex–> ventral&lateral corticospinal tract–> movement
Tract cerebellum takes to get head/eye control and posture
Cerebellum–> vestibular nuclei–> head/eye control&posture
how does cerebellum cause unconsious motor control?
Cerebellum –> medullary&pontine reticular formation–> medullary&pontine reticulospinal tract –>unconscious motor control
Deficits are_______ to the lesion due to ‘doublecrossing’ or because fibers remain ipsilateral
ipsilateral
Deficits are ipsilateral to the lesion due to _________or because fibers remain ipsilateral
‘doublecrossing’
Acute lesions to cerebellum are accompanied by
nausea/vomiting due to vertigo and ataxic on finger to nose or heel to shin
Cerebellar lesion symptoms resulting in nausea/vomiting can mimic what?
vestibular dysfunction… similar but
these pts are not necessarily ataxic on finger to nose or heel to shin
Ataxia =
uncoordinated muscle movement; errors in speed, range, force, timing
uncoordinated muscle movement; errors in speed, range, force, timing
Ataxia
Truncal ataxia =
wide-based, unsteady gait or difficulty sitting up; “drunklike”; localizes to lesion of
vermis
wide-based, unsteady gait or difficulty sitting up; “drunklike”; localizes to lesion of ______
vermis, this is truncal ataxia
Romberg test=
ask patient to stand in place, feet together and close eyes, if she or hee needs to step to stabilize, then deficit could be due cerebellar, proprioceptive, or vestibular
dysfunction; not specific to cerebellar disorders
Romber test is specific to cerebellar disorders
false
difficulty coordinating an extremity; manifests as dysmetria & dysrhythmia;
lesion of ipsilateral lateral hemispheres
Appendicular Ataxia
Appendicular Ataxia
difficulty coordinating an extremity; manifests as dysmetria & dysrhythmia;
lesion of ipsilateral lateral hemispheres
What are 6 signs of Appendicular Ataxia
Dysmetria Dysrhythmia Finger-nose-finger test heel-to-shin test Finger tapping Dysdiadochokinesia
overshoot/undershoot of a body part (limb) during movement toward a target
Dysmetria =
Dysmetria =
overshoot/undershoot of a body part (limb) during movement toward a target
–seen in appendicular ataxia
Dysrhythmia =
abnormal rhythm and timing of movement
–for appendicular ataxia
abnormal rhythm and timing of movement
Dysrhythmia
Finger-nose-finger test—
alternating between touching nose and examiner’s finger;
abnormal if patient’s finger shakes as it approaches target (either nose or finger)
–for appendicular ataxia
Finger tapping—
watch amplitude, rhythm, speed; cerebellar disorders cause abnormal rhythm, slowed speed, and varying amplitude
During finger tapping… cerebellar disorders cause ______rhythm,______ speed, and______ amplitude
abnormal
slowed
varying
Dysdiadochokinesia =
abnormal speed/rhythm when tapping hand with
palm/dorsum alternatively
abnormal speed/rhythm when tapping hand with
palm/dorsum alternatively
Dysdiadochokinesia
involuntary, rhythmic oscillation of a body part
tremor
Postural tremor =
tremor that occurs when a limb is held in a particular position (eg. open hands held extended); lesion of ipsilateral lateral hemisphere
tremor that occurs when a limb is held in a particular position (eg. open hands held extended); lesion of ipsilateral lateral hemisphere
Postural tremor
Action/intention tremor =
tremor that occurs when limb is in motion; lesion of ipsilateral lateral hemisphere
tremor that occurs when limb is in motion; lesion of ipsilateral lateral hemisphere
Action/intention tremor
Action/intention tremor occurs when limb is in motion; lesion is on _______ side
ispliateral hemisphre
Titubation =
tremor of trunk or head; lesion of vermis
Lesion in the vermis results in
titubation
Ocular dysmetria =
overshoot or undershoot of the eyes as patient focuses on a target; lesion of flocculonodular lobe (part of lateral hemispheres)
overshoot or undershoot of the eyes as patient focuses on a target; lesion of flocculonodular lobe (part of lateral hemispheres)
Ocular Dysmetria
Lesion of flocculonodular lobe results in
Ocular dysmetria–overshoot or undershoot of patient focusing on target
Flocculonodular lobe is in which part of hemisphere
lateral
Saccades =
quick, voluntary movement of eyes onto target; mediated by cortex—frontal & parietal eye fields
quick, voluntary movement of eyes onto target; mediated by cortex—frontal & parietal eye fields
Saccades
Slow eye movements =
involuntary movement of eyes mediated by cerebellum, vestibular nuclei & pathways, and extraocular motor nuclei
involuntary movement of eyes mediated by cerebellum, vestibular nuclei & pathways, and extraocular motor nuclei
Slow eye movements
Nystagmus =
rhythmic oscillations of the eyes; mediated by cortex; is an attempt by the cortex to correct abnormal signal to brain b/c of deficit of slow eye movements
mediated by cortex; is an attempt by the cortex to correct abnormal signal to brain b/c of deficit of slow eye movements
Nystagmus
Named after fast-beating phase of eye movements; eg. “right beating nystagmus”—fast phase of eye movements are to the______ & slow phase of eye movements to ____
right
left
Nystagmus is due to
Due to a deficit of the slow eye movement system
If nystagmus is acute in onset, can be accompanied by
vertigo, nausea, vomiting
Lesion of ________ can cause vertical, horizontal, or rotatory nystagmus
vermis/flocculonodular lobe
Pure vertical nystagmus
ALWAYS caused by CNS lesion (ie brainstem or cerebellar injury) direction-changing nystagmus in central
A horxontal or rotary nystagmus could be causes by:
a central or peripheral nervous system lesion
R beating horizontal nystagmus on R gaze, upgaze, downgaze –>
L VOR or L vestibular nuclear lesion (lesion could be central or peripheral with horizontal nystagmus)
R beating horizontal nystagmus on R gaze, L beating horizontal nystagmus on left gaze, verticle nystagmus on upgaze–>
likely to be cerebellum or one of it’s pathways
Slow saccades =
slowness in eye movements when trying to quickly look at target
Scanning (or ataxic) speech =
slow, effortful speech with difficulty articulating; lesion of lateral hemispheres
slow, effortful speech with difficulty articulating; lesion of lateral hemispheres
Scanning (or ataxic) speech
Hypotonia of ipsilateral limb results in
b/c cerebellum influences corticospinal tracts; pt falls to weak side (ipsilateral to lesion)
Lateral hemispheres of cerebellar are in charge of
motor planning for extremities
Motor pathway lateral hemisferes influence
LCST
If Lateral hemispheres are lesioned we see
Appendicular ataxia
Intermediate hemisphere is in charge of
distal limb coordination
Motor pathway intermediate hemisphere influences
LCST, rubrospinal tract
Lesion in intermediate hemisphere results in
Appendicular ataxia
Region of the cerebellum responsible for proximal limb
Vermis
trunk coordination and balace and vestibuloocular reflexes
Floculonodular lobe
Vermis influences which motor pathway
VCST, reticulospinal tract, vestibulospinal tract
Flocculonodular lobe influences which motor pathway
Medial longitudinal fasciculus
If the vermis is lesioned we see
truncal ataxia
If the flocculonodular lobe is lesioned we see
Nystagmus/slow saccades
Differential diagnosis for cerebellar dysfunction: vestibular dysnfunction
Vestibular dysfunction (also causes vertigo, difficulty walking, N/V, nystagmus); but usually no dysmetria or ataxia on finger to nose or heel to shin
Differential diagnosis for cerebellar dysfunction: corticospinal tract dysfunction
Corticospinal tract dysfunction—also causes hypotonia & weakness can be mistaken for ataxia
Differential diagnosis for cerebellar dysfunction: impaired proprioception
Impaired proprioception—these pts have a sensory ataxia (proprioceptive loss in feet makes walking difficult)
Clinical deduction for cerebellar disorders:
• Determine if process is acute (ie. occurred over minutes to hours) or chronic (slowly over many
days to weeks)
• Localize lesion
Cerebellar stroke (ischemic or hemorrhagic) Alcohol intoxication Drug overdose (eg. phenytoin) Multiple sclerosis ....examples of
Acute
Essential tremor
Spinocerebellar ataxia
Tumor (eg. astrocytoma)
Chronic alcoholism
Chronic
Pathogenesis of cerebellar stroke
the main arteries supplying blood (SCA, PICA, AICA) become diseased due to atherosclerosis; more commonly, the penetrating arteries from these arteries undergo arteriolosclerosis (thickening of vessels) from chronic HTN & other vascular risk factors (diabetes, smoking, high cholesterol)–> blood flow compromised –> ischemic stroke; or severe spike in blood pressure causes brittle vessel to rupturehemorrhagic stroke
Symptoms and onset of cerebellar stoke can be:
acute or sudden; may be felt right away and improve over weeks
Symtpoms of cerebellar stroke
inability to walk, frequent falls, nausea, vomit, vertigo
Signs of cerebellar stroke
dysmetria of ipsilateral arm/leg on finger-to-nose and heel-to-shin, mild ipsilateral dysdiadochokinesia,mild dysarthria, horizontal and verticle nystagmus
dysmetria of ipsilateral arm/leg on finger-to-nose and heel-to-shin, mild ipsilateral dysdiadochokinesia,mild dysarthria, horizontal and verticle nystagmus
signs of cerebellar stroke
Localization of cerebellar stroke
ips cerebellar hemisphere (lateral and flocculonodular lobes) and vermis
What risks do we look for cerebellar stoke?
HTN, smoking, diabetes, high cholesterol
One of the most common causes of ataxia
Alchohol intoxication
What are the acute symptoms of alcohol ataxia
inability to walk with frequent falls, no ‘checking’ of loss of balance, slurred speech;
caused by cerebellar neuronal dysfunction
Chronic symptoms of alcohol intoxication
: ataxia with walking/maintaining balance, difficulty with finger dexterity; caused by
Purkinje cell destruction & subsequent atrophy of vermis
Signs of alcohol ataxia
difficulty walking/tandem gait, dysarthria, dysmetria of limbs, nystagmus
what is the localization of alcohol intoxication
cerebellar vermis
The most common movement disorder
essential tumor
Essential tumor characteristics
- characteristic of tremor
- genetic pattern
- ect
Usually symmetric, bilateral, postural or action tremor that is persistent & visible; no other cause found;
autosomal dominant in 50% of patients; involves arms/hands, voice, head; chronic neurodegenerative
disorder; gradual loss of Purkinje cells
Signs of essential tumor
dysmetria, ataxic gait, head titubation
Localization of essential tumor
cerebellar hemispheres & vermis
Spinocerebellar ataxia is a group of ________ disorders caused by ___________ and _________
Group of autosomal dominant ataxic disorders caused by degeneration of afferent & efferent cerebellar pathways & destruction of Purkinje cells
Spinocerebellar ataxia is caused by a gene mutation which is:
each caused by a gene mutation resulting in a CAG triplet repeat expansion at different genetic loci
What symptoms do we see with spinocerebellar ataxia
-3 qualities
Slowly progressive ataxia of limbs/trunk, scanning speech, slowed saccades
Most cause profound cerebellar atrophy
Spinocerebellar ataxia
Higher morbidity & mortality than essential tremor
spinocerebellar ataxia
Localization of essential tumor
entire cerebellum
Most common childhood primary brain tumor
Astrocytoma
Astrocytoma is a low grade tumor comprised of ________
A low grade tumor composed of astrocytes (a type of glial cell & hemce a glioma)
Localization: tumor usually grows in
cerebellar hemisphere
Slowly progressive ipsilateral limb/truncal ataxia, scanning speech, nystagmus due to tumor
compressing on adjacent cerebellar parenchyma
Astrocytoma
Astrocytoma is slowly progressive _______ limb/truk ataxia
ipsilateral
nystagmus due to astrocytoma tumor
compressing on
adjacent cerebellar parenchyma
An astrocytoma show signs of increased intracranial pressure which cause:
—morning headaches, blurred vision,
may culminate in nausea/vomiting, difficulty concentrating in school
An autoimmune/inflammatory disorder affecting CNS white matter
Mutliple sclerosis
MS is more common in ____________ and each lesion is reffered to as _________
Predilection for young (25-40’s), white females • Each lesion is referred to as a ‘plaque’
In MS affects on: optic nerves Cerebral white matter regions Cerebellar white matter Medial longitudinal fasciculus spinal cord
Optic nerves–sudden vision loss
cerebral white matter–all descending/ascending cortex
cerebrellar white matter–especially middle cerebellar peduncle
Medial long fasciculus–white matter that mediates eye movements and if lesioned causes internucuer opthalmoplegia
How does MS affect the spinal cord
resluts in complete or incomplete spinal cord lesion in transverse section affecting ascending/descending tracts–called transverse myelitis
