6 Cerebellar Dysfunction Flashcards

1
Q

Cerebellum connection to brainstem

A
  • 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
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2
Q

Cerebellum inputs and outputs

A
  • inputs- mossy fibers (information); climbing fibers (timing)
  • outputs- Purkinje cells
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3
Q

Vestibulocerebellum

A
  • regulates equilibrium
  • involves vestibular nuclei, superior colliculus, reticulospinal system, primary motor cortex
  • deep nucleus- fastigial
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4
Q

Spinocerebellum

A
  • regulates gross limb movements
  • involves spinocerebellar tracts, vestibulospinal and reticulospinal tracts, motor cortex, red nucleus
  • deep nuclei- emboliform and globose
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5
Q

Cerebrocerebellum

A
  • 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
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6
Q

Stroke location leading to cerebellar dysfunction

A
  • basilar artery branching to superior cerebellar artery, AICA
  • vertebral artery branching to PICA, posterior spinal artery
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7
Q

Tumors to cerebellum

A
  • 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
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8
Q

Toxicity to cerebellum

A
  • 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
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9
Q

Infection to cerebellum

A
  • post-viral cerebellar ataxia, acute cerebellar ataxia, acute cerebellitis
  • most common in children who had chickenpox
  • most make complete recovery
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10
Q

Endocrine effects on cerebellum

A
  • hypothyroidism-induced ataxia is reversible with thyroid replacement therapy
  • Hasimoto’s/autoimmune thyroiditis not response to replacement therapy
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11
Q

Multiple sclerosis affecting cerebellum

A
  • ataxia, tremor

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

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12
Q

Nutrition affecting cerebellum

A

-gluten ataxia most common cause of sporadic idiopathic ataxia

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13
Q

Spinocerebellar ataxia

A
  • degenerative genetic condition

- multiple types, varying severity and age of onset

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14
Q

Friedrich’s ataxia

A
  • 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
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15
Q

Chiari malformation

A
  • herniation of part of cerebellum and/or brainstem through foramen magnum to upper spinal canal
  • often congenital
  • may be asymptomatic until adolescence or adulthood
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16
Q

Dandy-walker syndrome

A
  • 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
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17
Q

Hypoplasia

A
  • small or under-developed cerebellum
  • associated with several congenital conditions
  • developmental delays, ataxia, hypotonia, and nystagmus common
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18
Q

Types of ataxia

A
  • 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.
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19
Q

Dysdiadochokinesia

A

-impairments in rapid alternating movements

20
Q

Dyssynergia

A

-impairments in coordinating multi-joint movements

21
Q

Decomposition of movement

A

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

22
Q

Dysmetria

A

-impairments in ability to judge and scale movement distances

23
Q

Cerebellar tremor

A

-action or intention tremor, not resting

24
Q

Cerebellar ataxic gait

A

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

25
Oculomotor impairments
-impaired smooth pursuits, saccades, VOR cancellation, nystagmus
26
Motor learning and motor control impairments
- 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)
27
Dysarthria
-uneven articulation, slurred words, variations in pitch and volume
28
Error-based vs reinforcement learning
- 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
29
Compensatory approach
- 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
30
Recovery approach
- 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
31
Friedrich’s ataxia gait
- 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
32
Use of PT + rTMS
- 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
33
Optokinetic stimulation
- watch a screen with black dots moving at unpredictable time, speed, direction while performing balance activities - trend for improvement in function
34
Coordination screen
- RAM - finger opposition - finger to nose - heel to shin - tandem walking - retro-ambulation - grapevine/carioca
35
Ataxia outcome measures
- Scale for the assessment and rating of ataxia (SARA) - international cooperative ataxia rating scale (ICARS) - Friedrich’s ataxia rating scale (FARS)
36
SARA
- 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
37
ICARS
- 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)
38
FARS
- sub scales- ataxia, ADLs, neurological examination | - 0-159 (higher score is more disability)
39
Postural stability outcome measures
- Clinical test of sensory interaction and balance - sensory organization test - push and release test - retropulsive pull test
40
Push and release test
-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
41
Retropulsive pull test
-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
42
Functional balance outcome measures
- BBS - DGI - FTSTS - Functional reach test - TUG
43
Dynamic gait index
-8 walking tasks 0-4 -scored 0-24 (lower number is more dysfunction <=19/24 is increased fall risk
44
FTSTS
>13 seconds indicates balance dysfunction
45
Functional reach test
<15 cm = fall risk