Cerebellar Dysfunction Flashcards
Vestibulocerebellum, spinocerebellar, cerebrocerebellum
V- floculonodular lobe
S - vermis/paravermal hemispheres
C - lateral hemisphere
Superior cerebellar peduncle connection to brainstem
- Attaches to midbrain
- Contains cerebellar efferent fibers
Middle cerebellar peduncle connection to brainstem
- Attaches to the pons
- Contains afferent fibers from cerebral cortex
Inferior cerebellar peduncle connection to brainstem
- Attaches to the medulla
- Contains afferent fibers from the brain stem and SC
- ALSO contains efferent fibers from the vestibular and reticular nuclei
Pathways: IPSI or BIL
Most are ipsilateral except vestibulocerebellum has bilateral control
Input fibers
- Mossy fibers (information)
- Climbing fibers (timing)
Output fibers
- Purkinje cells
Vestibulocerebellum function and inputs
- Function: Regulates equilibrium
- Inputs: Vestibular nuclei and superior colliculus (eye and head position/movement)
Vestibulocerebellum outputs and deep cerebellar nucleus
- Outputs: Med vestibular nuclei ( VOR) +
lat vestibular nuclei, reticulospinal system, PMC (postural reactions) - DCN: Fastigial
Spinocerebellum function and inputs
- Function: Regulates gross limb movement
- Inputs: Spinocerebellar tracts
Spinocerebellum outputs and deep cerebellar nucleus
- Outputs: Vestibulospinal + reticulopinal tracts, motor cortex + red nucleus
- DCN: Emboliform, globose
Cerebrocerebellum function and inputs
- Function: Regulates distal limb voluntary movements, motor planning, and timing
- Inputs: Cerebral cortex via pontine nuclei
Cerebrocerebellum outputs and deep cerebellar nucleus
- Outputs: Motor + premotor cortices via thalamus, red nucleus to activate rubrospinal tract
- DCN: Dentate
Wernicke-Korsakoff syndrome
Vitamin B/thiamine deficiency due to alcohol abuse
Pharmacological agents that can cause ataxia
- Anti-convulsants
- Anti-neoplastics
- Lithium (BIPOLAR)
Drugs that can cause ataxia
Cocaine + heroine
Infections that can cause ataxia
Chickenpox is most common
Endocrine issues that can cause ataxia
- Hypothroidism (reversible with thyroid replacement therapy)
- Hashimoto’s (no responsive to thyroid replacement therapy)
Nutrition issues that can cause ataxia
GLUTEN
Spinocerebellar ataxia
- Degenerative condition that is based on autosomal dominant or recessive genes
Friederich’s ataxia
- Age of onset 8-15 years
- Presents as clumsiness with gait
- Common to have scoliosis and gait deformities
- Eventually dies of heart failure
Dandy-Walker syndrome
- Congenital malformation characterized by enlarged 4th ventral and complete/partial absence of vermis
- Intellectual problems common due to hydrocephalus
Dyssynergia
Impairments in ability to coordinate multi-joint movements
Motor control and learning impairments
- Cerebellum plays an important role in motor memory formation of coordination tasks
- Important for shifting movement performance to more automatic state
- Cerebellar dysfunction can hinder learning and cause slower rate of learning
- Disrupts feedforward but doesn’t effect feedback
Error-based vs reinforcement learning
- Reinforcement learning provides greater retention
- Reinforcement learning is intact in individuals with cerebellar damage but greater variability with performance (poor retention with error-based learning)
Compensatory approaches to ataxia
- Simple, single joint movements
- Visual/verbal cues to improve gait
- Assistive devices for posture/balance/mobility
- Compression garments
- Cooling a limb may have temp benefit
Recovery approaches to ataxia
- Biofeedback via EMG activity of mm activation/postural sway with computer game
- Strengthening/balance/ocular exercises to improve postural stability
- Locomotor training
PT + rTMS and ataxia
- Amplitude of lateral head and body sway reduced = improved dynamic balance in earlier stages of disease
- No effect on gait speed
Scale for the Assessment and Rating of Ataxia (SARA)
- Provides quantitative assessment of impairments related to cerebellar ataxia
- Also used in ataxic stroke
- Evaluates gait, stance, sitting, speech, and various limb coordination tasks
SARA cut-off scores
- Gait: <8 = independent; <11.5 = quad cane; <12.25 = walker
- ADL dependence: <5.5 = independent; <10 = Min A; <14.25= Mod A; >23 = Max A
International Cooperative Ataxia Rating Scale (ICARS)
- Evaluates impairment as a result of hereditary ataxia with regard to postural/gait disturbance, limb ataxia, dysarthria, oculomotor disorders
- Higher the score = greater impairment (0-100)
- No cut-off scores
Friedereich’s Ataxia Rating Scale (FARS)
- Assess ataxia and impairment based on diagnosis by same name
- 3 subscales: ataxia, ADLs, neuro eam
- Higher the score = greater impairment (0-159)
- No cut-off scores
Push and Release Test
- Assesses postural instability by ability to regain balance
- Lean posteriorly into examiner’s hands and hands are removed, number of steps is score
- No cut-off scores
Push and Release Test scoring
0 - Recovers ind with 1 step
1 - 2 to 3 steps required but able to recovers ind
2 - 4 or more steps required but recovers ind
3 - Able to step but requires assist to prevent fall
4 - Falls without attempting to step/unable to stand without assistance
Retropulsive Pull Test
- Assesses nonvestibular-related balance impairment (PD)
- Examiner stands behind subject and pulls subject’s shoulders backwards
Retropulsive Pull Test scoring
0 - recovers independent with 1-2 steps or ankle reaction
1 - Recovers independent with 3+ steps
2 - Requires assistance to prevent fall
3 - Very unstable; loses balance spontaneously
4- Unable to stand without assist
