cerebellar ataxia

Question 1

ataxia

Answer 1

Ataxia can mean:
Loss of control of body movements Poorly coordinated movement Unsteadiness

potential causes:
vestibular
cerebellar
sensory

difference, 
observation 
subjective hx
objective exam 
background knowledge

Question 2

vest
cerebellar
sensory

Answer 2

Vestibular
“Spinning”
Slow gait, reduced head movement
Vestibular tests positive Normal limb coordination Normal sensation Positive Romberg

Cerebellum “Unsteady / drunk” Cerebellar signs
Poor limb coordination - heel shin test.
Intention tremor
Wide base, variable
foot placement in gait

Sensory
“Tripping, nervous” Visual dependence Deliberate foot placement in gait Anticipatory balance strategies Positive Romberg Normal limb coordination Reduced sensation

Question 3

sensory ataxia

Answer 3

Loss of sensory input (proprioception) due to upper or lower motor neuron lesion
Reduced awareness of joint position, spatial relationship
between limb segments, characteristics of support surface
Will be associated with other neurological deficits related to the causative injury

Examples:
UMNL: MS (lesions in parietal lobe), SCI (incomplete: posterior
cord)
LMNL: Peripheral neuropathy (sensory > motor), Charcot- Marie-Tooth

Question 4

physio mgmt of sensory ataxia

Answer 4

Assessment: Detailed neurological evaluation, including gait (temporal-spatial and video), balance and falls risk

Treatment
Balance rehabilitation targeting proprioceptive inputs (eyes closed, vary support surface, challenge reactive strategies)

Compensation: ankle foot orthosis, gait aids

Sensory input: foot mobilisations, “spiky ball”, surfaces

bare foot exercises
vary the surfaces

Question 5

cerebellum anatomy

Answer 5

“Little brain”
Posterior fossa
Highly ridged surface
10% brain volume
50% total neurons
half of the neurons of the brain
dense structure 

3 lobes in the cerebellum
midline - vermis - dense

close to pons and 4th ventricle

all the ridges allow for loads of neurons to fit in

spinocerebellum - spinal execution

neocerebellum - motor planning and motor learning
learn new motor skills

Question 6

role of cerebellum in movement

Answer 6

Controls error in movement

Interprets and optimises sensory feedback

Imparts new motor skills for motor learning

Question 7

3 distinct functional regions

Answer 7

Vestibulocerebellum: Eye  movements, modifies  vestibular influences on  posture and balance
inputs - vestibular organs
legs trunk and eye
trunes balance 
tunes VOR

Spinocerebellum: Regulation of muscle tone, posture, locomotion
inputs somato-sensory and muscle afferents from SC
ouput to SC
tunes and adjusts ongoing movements and muscle tone

Cerebrocerebellum: Preparation for movement, initiation, precise control and timing
inputs primary motor cortex
outputs
primary motor and premotor cortex
function = initiation of skilled movement

Question 8

causes of cerebellar ataxia

Answer 8

Damage or dysfunction affecting the cerebellum
AND / OR
its input or output pathways

Question 9

lesions of the cerebellum

Answer 9

Developmental abnormality
TBI
Stroke / ABI
Tumour
MS
Hereditary disease (Friedreich’s)
Degenerative (spino-cerebellar-degeneration)
Drug and alcohol intoxications

Question 10

cerebellar lesion

Answer 10

Ipsilateral lesion → mostly ipsilateral signs
“Double decussation”
Output fibres cross to contralateral VL nucleus of thalamus
Thalamus relays to cortex Corticospinal tract crosses again at medulla
Some bilateral signs

Question 11

cerebellar signs

Answer 11

Limb movement  Dyssynergia  Dysmetria  Tremor
Dysdiadochokinesia  Hypotonia
Balance and gait dysfunction
Oculomotor: gaze stability  Nystagmus
Impaired smooth pursuit
Dysarthria

Question 12

dyssynergia / dysmetria

Answer 12

Dyssynergia: deficits in multi-joint movements, decomposition of movement
Dysmetria: variability of spatial path, lack of accuracy in hitting
the target
Hypermetria: overshooting Hypometria: undershooting
Tests:
Finger to nose Heel to shin
Abnormal agonist-antagonist relationship

Question 13

re-bound phenomenon

Answer 13

Flex elbow against examiner
Examiner releases resistance
Unable to stop resultant rebound

Delay is in antagonistic “breaking” response

Question 14

dysdiadochokinesia

Answer 14

Irregular pattern of rapid alternating movement
Pronation / supination
Tapping tasks upper and lower limbs
With persistence
error
 amplitude of displacement

Question 15

tremor

Answer 15

Action tremor
During movement: kinetic tremor
Maintaining a posture: postural tremor
Truncal or head: titubation (characteristic 3Hz) (Tremor at rest not seen in pure cerebellar dysfunction)

Intention tremor: increase in tremor amplitude when approaching a target (*may be confused with dysmetria)

Most marked at end of movement (terminal tremor)

Question 16

hypotonia

Answer 16

Diminished resistance to passive movement
Usually only seen early after lesion / injury
Mechanism unclear
altered tonic background activity of spinal interneurones loss of muscle spindle response
Deep tendon reflexes may produce pendular movement

Question 17

strength

Answer 17

Ability to produce maximum force unchanged

Ability to sustain it over time is impaired Drift when asked to hold a limb steady Variability in maintaining constant force Impaired agonist / antagonist coordination

Reduced rate of force generation (power)

Question 18

dysarthria

Answer 18

Scanning speech  Hesitation
Accentuation of some syllables
Incorrect timing of pauses
Speech is slurred in 50%
Anterior lobe lesions (vulnerable  to alcoholic cerebellar  degeneration)

Question 19

nystagmus

Answer 19

Abnormal balance of eye control
Slow drift in one direction/fast corrective movement
Maximal with eye movement in the direction of the fast phase
By convention named by direction of fast phase
Direction of fast phase corresponds to side of cerebellar dysfunction
End point nystagmus vs Gaze evoked nystagmus

Question 20

eye movements

Answer 20

Smooth pursuit: Tracking movement of the eyes (following a moving object)
Saccades: Fast movements of the eyes
Test by getting patient to look from one object to another
Abnormalities
Hypo/Hyper metric saccades Post-saccadic drift
Jerky smooth pursuit

Question 21

effects on motor tasks

Answer 21

Errors of
rate amplitude accuracy force
Poor control over postural adjustments

Question 22

adaptive motor behaviours

Answer 22

Dependency on visual information
Hold themselves stiffly with wide base of support
Shorten range
Keep arms close to body; decrease need for multijoint co- ordination
Use arms to stand up

Question 23

effect on posture and balance

Answer 23

Increased postural sway
Head and truncal tremor between 2 and 5 Hz Lesions of anterior lobe, vermis and fastigial n. Sway greatest in AP direction
Impaired postural reactions to perturbation Hypermetria
Impaired anticipatory postural adjustments Imbalance during self-generated movements
Tendency to fall to side of lesion

Question 24

effect on gait

Answer 24

Temporal-spatial parameters:  Prolonged double support phase  Shorter stride length
Wide base (increased step width) or variable base
Kinematics:
Greater variability
Poor inter-limb coordination leads to foot placement errors

Question 25

cerebellar assessment

Answer 25

Specific Cerebellar Tests
Finger-nose Finger-finger
Rapid alternating movements Finger tapping test
Heel to shin Rebound test Pendular sign

General Tests
Functional Reach  Rhomberg’s test  Sharpened Rhomberg
SLS	EO/ECTandem walking  CTSIB
Gait analysis
Nine hole peg test

Question 26

rehab for ataxia?

Answer 26

Cerebellum is crucial to motor learning
Cerebellum is involved in predictive control

Implications of a cerebellar lesion:
Motor learning is slower
Trial and error practice will not work
Patients need guidance on task-specific training
Complex movements need to be broken into component parts
Patient needs to use cognitive strategies

Functional gains can be achieved

Question 27

treatment strategies

Answer 27

Use external constraints
Encourage practice of smooth movements including stopping
and starting
Include activities that require sustained force
involve the production of rapid initial burst of agonist activity
Augmented feedback: visual / auditory
Avoid use of “trial and error” for motor learning

Question 28

compensatory approaches

Answer 28

Encourage decomposition of movement into simpler single joint movements
Visual and verbal cues to aid walking speed and stride length
Assistive technology to aid computer use
Aids to help posture, balance and mobility:
4 point gait with 2 crutches gives wide base of support but can be tricky to coordinate
Rollator provides postural stability and is easy to manoeuvre, but less adaptable than crutches

Question 29

treatment strategies: tremor

Answer 29

Lycra garments (“second skin”) may provide visco-elastic resistance to tremor
Single case studies only
Limited by difficulty in donning and doffing
Weights:
Weighted caps or belts for head or truncal titubation Limb weights to increase inertia of limb
Addition of load requires adaptive scaling of agonist– antagonist activity, impaired in cerebellar disease
Cooling may temporarily reduce tremor

Question 30

restoration gait and balance

Answer 30

Balance re-training  Manipulate vision,  proprioceptive and vestibular  information
Safe place  Progress
Gait training
Parallel bars
BWSTT (body weight
supported treadmill training

Vary
support surface environmental constraints timing
Falls risk assessment

Question 31

effectiveness of restoration strategies

Answer 31

Prolonged interventions (3-12 months): reduced force variability, improved inter-limb coordination (Schalow 2006,Kara Harris-Love 2004)
Biofeedback and relaxation therapy effective in reducing tremor
(Guercio 2001)
Improved balance with video-game biofeedback of Centre of
Pressure (Betker 2006)
Improved motor performance and goal attainment with coordinative training (Ilg et al 2009)

Question 32

gaze stabiltiy exercises

Answer 32

Active eye and head movements between two stationery targets
Visual fixation on a target; slow head movements
Progress to more dynamic tasks, including standing balance challenges or walking with head turns / active eye movements

More on this in Week 7 of Neurology II – Vestibular Rehabilitation