Cerebellar Ataxia Flashcards
What are the 3 functional regions of the cerebellum?
- Vestibular cerebellum
- Spinocerebellum
- Cerebrocerebellum
What is the function of the vestibular cerebellum?
- Controls balance & eye movement
- Via output to vestibular nuclei & input from semicircular canals
What is the function of the spinocerebellum?
- Controls ongoing execution of limb movements
- Regulates muscle activity to allow for variations in load & smoothness
What is the function of the cerebrocerebellum?
- Preparation, anticipation & initiation of movement
- Precision, timing & sequencing
- Coordination of movements to a visual target
What does the cerebellar blood supply consist of?
Branching off basilar artery:
- Superior CA (SCA)
- Anterior inferior CA (AICA)
Branching off vertebral arteries:
- Posterior inferior CA (PICA)
What is the overall role of the cerebellum?
- Regulates motor control
- Constructs synergies
- Regulates intensity of movement
- Perception, cognition& language
- Movement to movement error correction
- Timing & sequencing of muscle activation
- Contributes to postural control during external perturbations or intentional actions
- Mental practice of movement & visuospatial tasks
- Perception of time intervals & velocity of moving objects (e.g. crossing the road)
What is cerebellar ataxia?
- Abnormal coordination affecting speed, amplitude, accuracy & force of movement
- Severe loss of dexterity
- Result of damage to neurons in the cerbellum
What are the other types of ataxia?
- Sensory (due to loss of proprioception)
- Vestibular (due to dysfunction of vestibular system)
What are the causes of cerebellar ataxia?
- Focal lesions (stroke, TBI, tumour, MS)
- Exogenous substances (alcohol, anti-epileptics)
- Vitamin B12 deficiency
- Non-hereditary cerebellar degeneration
- Hereditary cerebellar degeneration
- Arnold-Chiari malformation (cerebellar tonsils pushed down through foramen magnum - may require surgery)
What are some of the causes of non-hereditary cerebellar degeneration?
- Idiopathic late onset cerebellar ataxia
- Alcohol abuse
- Coeliac disease
What are the types of hereditary cerebellar degeneration?
- Autosomal dominant (spinocerebellar ataxia, episodic ataxia)
- Autosomal recessive (Friedrich’s ataxia, ataxia-telangiectasia)
- Generally always present in childhood (managed by paediatrics)
What are the characteristics of ataxic motor performance?
- Dysmetria (over/undershooting)
- Rebound phenomenon (delayed antagonist burst)
- Dysdiadochokinesia
- Dyssynergia or decomposition (poor coordination & smoothness)
- Tremor (intentional or postural)
- Dysarthria (poor coordination of speech production muscles)
- Nystagmus
What does assessment of ataxic motor performance involve?
- Assessment of rapid alternating movements
- Assessment of postural sway (EO/EC)
- Heel/shin
- Heel over foot
- Finger nose
- Rebound test
What does assessment of cerebellar ataxia involve?
- Assessment of activities
- Observe missing important components
- Observe adaptive strategies
- Assess changing speed/direction, stopping on command, dual tasking
What are some of the measures used when assessing cerebellar ataxia?
(All valid & reliable)
- Accuracy
- Successful repetitions in a given time period
- 10MWT
- TUG
- Step test
- Functional reach
- 6MWT
- 9HPT
What are the typical adaptive motor behaviours in cerebellar ataxia?
- Restriction of amplitude of movement
- Restriction of degrees of freedom
- Excessive pre-shaping & use of support surface during UL tasks
- Excessive BOS, stepping & use of arms during standing & walking
- Increased speed & difficulty slowing down in walking
- Increased variability of performance
What did Pulliyath et al 1998 find regarding gait in cerebellar ataxia patients?
Cerebellar patients demonstrated increase variability, decreased PF at push off & decreased knee yield during gait compared with controls
What did Bastien et al 1996 find regarding reaching in cerebellar ataxia patients?
- Cerebellar patients had an abnormally curved wrist path due to dyssynergia or decomposition of movement
- Suggested this was due to cerebellum’s inability to predict & compensate for torques generated at various joints
- CIs: Do whole task practice using multiple joints
What did Bastien et al 2000 find regarding reaching in cerebellar ataxia patients?
- Elbow flexion tasks were performed significantly better in cerebellar patients when the shoulder & elbow were fixed compared with when they were not fixed
- CIs: Use fixed position for patients who are chronic progressive, prevent/change in recoverable patients
What did Deiner & Dichgans et al 1992 find regarding heel raises in cerebellar ataxia patients?
- During heel raises controls & cerebellar patients demonstrated the same EMG sequence (tib ant, quads, gastrocs), but cerebellar patients had disordered timing & poor build up of EMG activity
- CIs: Train timing
What did Morton et al 2004 find regarding stepping in cerebellar ataxia patients?
- Cerebellar patients had greater dysmetria in knee flexion when stepping over and obstacle than in normal walking
- CIs: Train flexibility of performance in recoverable patients
What did Lang & Bastien et al 2002 find regarding task performance in cerebellar ataxia patients?
- With 25 practices of a task, cerebellar patients can improve performance
- The addition of a second task resulted in regression to original performance
- CIs: Train dual tasks in recoverable patients, consider safety of dual tasking in chronic progressive patients
What did Ballet et al 1987 find regarding balance & coordination training in cerebellar ataxia?
- Treated TBI patients with cerebellar ataxia with balance & coordination training & reduction in use of UL
- Results indicated significant improvement in function & independent walking ability
- CIs: Train balance/walking, decrease adaptive strategies
What did Miyai et al 2012 find regarding physio interventions for cerebellar degeneration?
- RCT of patients with cerebellar degeneration (chronic progressive)
- 2 hours PT & OT daily for 4 weeks
- Intervention included rehab for coordination, balance & ADLs
- Results showed increased walking speed, decreased falls & improved ADLs (maintained at 12 & 24 weeks)
- CIs: High intensity practice can improve chronic progressive patients
What did the 2014 Consensus Statement by Ilg et al state?
- Physio is a mainstay of managing people with cerebellar ataxia
- Physio should be intensive
- Physio must be life-long
How should ataxia be trained?
- Spatial accuracy
- Timing accuracy
- Modified task practice
- External constraints
- Ensure patient cannot use adaptive strategies
- Increase complexity
What does training for spatial accuracy involve?
- Tasks where excessive movements are constrained
- Feedback is implicit in the task
What does training for timing accuracy involve?
- Closed tasks (same every time) which require rhythm
- Open tasks (change each time) which require predictive timing
How can complexity of training be increased?
- Withdraw external constraints
- Increase amplitude of movement
- Change speed, amplitude, direction & force
- Add balance requirements
- Stop mid-task
- Train automaticity
