6 Cerebellar Dysfunction

Question 1

Cerebellum connection to brainstem

Answer 1

• superior cerebellar peduncle- attach to midbrain, contains cerebellar efferent fibers
• middle cerebellar peduncle- to pons, afferent fibers from cerebral cortex
• inferior cerebellar peduncle- to medulla, afferent from brainstem and spinal cord, efferent to vestibular and reticular nuclei in brainstem

Question 2

Cerebellum inputs and outputs

Answer 2

• inputs- mossy fibers (information); climbing fibers (timing)
• outputs- Purkinje cells

Question 3

Vestibulocerebellum

Answer 3

• regulates equilibrium
• involves vestibular nuclei, superior colliculus, reticulospinal system, primary motor cortex
• deep nucleus- fastigial

Question 4

Spinocerebellum

Answer 4

• regulates gross limb movements
• involves spinocerebellar tracts, vestibulospinal and reticulospinal tracts, motor cortex, red nucleus
• deep nuclei- emboliform and globose

Question 5

Cerebrocerebellum

Answer 5

• regulates distal limb voluntary movements
• motor planning
• timing/rhythm
• involves cerebral cortex via pontine nuclei, motor and pre-motor cortices via thalamus, red nucleus to activate rubrospinal tract
• deep nucleus- dentate

Question 6

Stroke location leading to cerebellar dysfunction

Answer 6

• basilar artery branching to superior cerebellar artery, AICA
• vertebral artery branching to PICA, posterior spinal artery

Question 7

Tumors to cerebellum

Answer 7

• can affect cerebellum, pons, medulla, and/or fourth ventricle
• most common primary posterior fossa tumors- medulloblastoma, astrocytoma
• most common primary sites of posterior fossa metastases- lung (50%), breast, kidney, melanoma

Question 8

Toxicity to cerebellum

Answer 8

• cerebellar cortex and Purkinje neurons especially vulnerable to intoxication and poisoning
• most common is alcohol-related- Wernicke-Korsakoff syndrome, vitamin B1/thiamine deficiency
• anti-convulsants, anti-neoplasticism, lithium salts
• cocaine, heroin
• mercury, lead, manganese

Question 9

Infection to cerebellum

Answer 9

• post-viral cerebellar ataxia, acute cerebellar ataxia, acute cerebellitis
• most common in children who had chickenpox
• most make complete recovery

Question 10

Endocrine effects on cerebellum

Answer 10

• hypothyroidism-induced ataxia is reversible with thyroid replacement therapy
• Hasimoto’s/autoimmune thyroiditis not response to replacement therapy

Question 11

Multiple sclerosis affecting cerebellum

Answer 11

• ataxia, tremor

- large-amplitude, postural tremors most commonly affect arms (sometimes head, neck, vocal cords, trunk)

Question 12

Nutrition affecting cerebellum

Answer 12

-gluten ataxia most common cause of sporadic idiopathic ataxia

Question 13

Spinocerebellar ataxia

Answer 13

• degenerative genetic condition

- multiple types, varying severity and age of onset

Question 14

Friedrich’s ataxia

Answer 14

• early-onset hereditary spinal ataxia (8-15 y/o)
• progressive condition, initially clumsiness of gait
• scoliosis and foot deformities common
• cause of death usually heart failure

Question 15

Chiari malformation

Answer 15

• herniation of part of cerebellum and/or brainstem through foramen magnum to upper spinal canal
• often congenital
• may be asymptomatic until adolescence or adulthood

Question 16

Dandy-walker syndrome

Answer 16

• congenital malformation of enlargement of fourth ventricle and partial or complete absence of cerebellar vermis
• varying degrees of physical and intellectual impairment
• hydrocephalus and progressive skull enlargement common

Question 17

Hypoplasia

Answer 17

• small or under-developed cerebellum
• associated with several congenital conditions
• developmental delays, ataxia, hypotonia, and nystagmus common

Question 18

Types of ataxia

Answer 18

• cerebellar- Romberg’s imbalance with eyes open and closed
• sensory- loss of proprioception, Romberg’s imbalance with eyes closed only
• vestibular- imbalance when forced to relay on vestibular cues or with head turns, also nausea, dizziness, etc.

Question 19

Dysdiadochokinesia

Answer 19

-impairments in rapid alternating movements

Question 20

Dyssynergia

Answer 20

-impairments in coordinating multi-joint movements

Question 21

Decomposition of movement

Answer 21

-breaking down movement into series of smaller, single-joint motions

Question 22

Dysmetria

Answer 22

-impairments in ability to judge and scale movement distances

Question 23

Cerebellar tremor

Answer 23

-action or intention tremor, not resting

Question 24

Cerebellar ataxic gait

Answer 24

-wide BOS, variable step length and limb trajectories, path deviations, decomposition of movement

Question 25

Oculomotor impairments

Answer 25

-impaired smooth pursuits, saccades, VOR cancellation, nystagmus

Question 26

Motor learning and motor control impairments

Answer 26

• Putamen and anterior cerebellum are more activated across both learning and automatization stages, supporting their crucial role in long-term motor memory formation for coordination tasks
• those with cerebellar damage improve movements to limited extent with practice, but performance reverts to pre-practice levels under dual-task condition
• cerebellum is important for shifting movement performance to automatic state
• those with cerebellar dysfunction demonstrate slower learning curves
• cerebellar damage disrupts predictive feed forward motor adaptations but not reactive feedback (lower neural centers)

Question 27

Dysarthria

Answer 27

-uneven articulation, slurred words, variations in pitch and volume

Question 28

Error-based vs reinforcement learning

Answer 28

• error-based- learner has access to error data and makes corrections on trial-by-trial basis
• reinforcement learning- learner receives success/failure info but no error data, so need to explore options
• controls demonstrate greater retention with reinforcement learning
• cerebellar dysfunction showed poor retention with error-based learning. More rapid learning with closed-loop reinforcement learning.
• reinforcement learning is intact in those with cerebellar damage but indirectly affected by increased motor noise/variability

Question 29

Compensatory approach

Answer 29

• simple, single-joint movements
• visual and verbal cues to improve gait
• AD for computer use, posture, balance, and mobility
• decrease tremor with compression garments (increase viscoelastic resistance or inertia of limb)
• decrease tremor by loading limb (weighted vest best evidence)
• cooling a limb to temporarily reduce tremor

Question 30

Recovery approach

Answer 30

• biofeedback in form of EMG activity of muscle activation and postural sway
• strength, balance, ocular exercises to improve postural stability and walking
• BWSTT 5 days/week for improved walking distance
• cortical and cerebellar stimulation may cause functional improvements

Question 31

Friedrich’s ataxia gait

Answer 31

• slower gait velocity, longer gait cycles compared to age-matched norms
• inverse relationship between age and velocity and between age and stride length
• significant correlation between FARS and locomotor impairment severity

Question 32

Use of PT + rTMS

Answer 32

• improved ICARS
• no change in walking speed, step width, total length of center of pressure
• amplitude of head and body sway when walking were reduced
• combo intervention may have positive effects on dynamic balance impairments with degenerative cerebellar ataxia in early stages of disease

Question 33

Optokinetic stimulation

Answer 33

• watch a screen with black dots moving at unpredictable time, speed, direction while performing balance activities
• trend for improvement in function

Question 34

Coordination screen

Answer 34

• RAM
• finger opposition
• finger to nose
• heel to shin
• tandem walking
• retro-ambulation
• grapevine/carioca

Question 35

Ataxia outcome measures

Answer 35

• Scale for the assessment and rating of ataxia (SARA)
• international cooperative ataxia rating scale (ICARS)
• Friedrich’s ataxia rating scale (FARS)

Question 36

SARA

Answer 36

• quantitative assessment of impairments related to cerebellar ataxia
• gait, stance, sitting, speech, various limb coordination tasks
• 0-40 (no to severe ataxia)
• gait <8 independent, <11.5 quad cane, <12.25 walker
• ADL <5.5 independent, <10 min dependent, <14.25 mod dependent, >23 maximal dependence

Question 37

ICARS

Answer 37

• impairment as a result of hereditary ataxia with regard to postural and gait disturbance, limb ataxia, dysarthria, oculomotor disorders
• 0-100 (no to max impairment)

Question 38

FARS

Answer 38

• sub scales- ataxia, ADLs, neurological examination

- 0-159 (higher score is more disability)

Question 39

Postural stability outcome measures

Answer 39

• Clinical test of sensory interaction and balance
• sensory organization test
• push and release test
• retropulsive pull test

Question 40

Push and release test

Answer 40

-subject leans into examiner’s hands, suddenly remove hand
0 = recovers independently 1 step
1 = 2-3 steps to recover
2 = 4+ steps
3 = able to step, requires assistance to prevent fall
4 = falls without attempting to step or unable to stand without help

Question 41

Retropulsive pull test

Answer 41

-assesses nonvestibular-related balance impairment (part of UPDRS)
-stand behind subject, pull on shoulders
0 = 1-2 steps to recover or ankle reaction
1 = 3+ steps to recover
2 = requires assistance to prevent fall
3 = very unstable, loses balance spontaneously
4= unable to stand without assistance

Question 42

Functional balance outcome measures

Answer 42

• BBS
• DGI
• FTSTS
• Functional reach test
• TUG

Question 43

Dynamic gait index

Answer 43

-8 walking tasks 0-4
-scored 0-24 (lower number is more dysfunction
<=19/24 is increased fall risk

Question 44

FTSTS

Answer 44

> 13 seconds indicates balance dysfunction

Question 45

Functional reach test

Answer 45

<15 cm = fall risk