6 Cerebellar Dysfunction Flashcards
Cerebellum connection to brainstem
- 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
Cerebellum inputs and outputs
- inputs- mossy fibers (information); climbing fibers (timing)
- outputs- Purkinje cells
Vestibulocerebellum
- regulates equilibrium
- involves vestibular nuclei, superior colliculus, reticulospinal system, primary motor cortex
- deep nucleus- fastigial
Spinocerebellum
- regulates gross limb movements
- involves spinocerebellar tracts, vestibulospinal and reticulospinal tracts, motor cortex, red nucleus
- deep nuclei- emboliform and globose
Cerebrocerebellum
- 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
Stroke location leading to cerebellar dysfunction
- basilar artery branching to superior cerebellar artery, AICA
- vertebral artery branching to PICA, posterior spinal artery
Tumors to cerebellum
- 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
Toxicity to cerebellum
- 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
Infection to cerebellum
- post-viral cerebellar ataxia, acute cerebellar ataxia, acute cerebellitis
- most common in children who had chickenpox
- most make complete recovery
Endocrine effects on cerebellum
- hypothyroidism-induced ataxia is reversible with thyroid replacement therapy
- Hasimoto’s/autoimmune thyroiditis not response to replacement therapy
Multiple sclerosis affecting cerebellum
- ataxia, tremor
- large-amplitude, postural tremors most commonly affect arms (sometimes head, neck, vocal cords, trunk)
Nutrition affecting cerebellum
-gluten ataxia most common cause of sporadic idiopathic ataxia
Spinocerebellar ataxia
- degenerative genetic condition
- multiple types, varying severity and age of onset
Friedrich’s ataxia
- 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
Chiari malformation
- herniation of part of cerebellum and/or brainstem through foramen magnum to upper spinal canal
- often congenital
- may be asymptomatic until adolescence or adulthood
Dandy-walker syndrome
- 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
Hypoplasia
- small or under-developed cerebellum
- associated with several congenital conditions
- developmental delays, ataxia, hypotonia, and nystagmus common
Types of ataxia
- 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.
Dysdiadochokinesia
-impairments in rapid alternating movements
Dyssynergia
-impairments in coordinating multi-joint movements
Decomposition of movement
-breaking down movement into series of smaller, single-joint motions
Dysmetria
-impairments in ability to judge and scale movement distances
Cerebellar tremor
-action or intention tremor, not resting
Cerebellar ataxic gait
-wide BOS, variable step length and limb trajectories, path deviations, decomposition of movement
Oculomotor impairments
-impaired smooth pursuits, saccades, VOR cancellation, nystagmus
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)
Dysarthria
-uneven articulation, slurred words, variations in pitch and volume
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
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
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
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
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
Optokinetic stimulation
- watch a screen with black dots moving at unpredictable time, speed, direction while performing balance activities
- trend for improvement in function
Coordination screen
- RAM
- finger opposition
- finger to nose
- heel to shin
- tandem walking
- retro-ambulation
- grapevine/carioca
Ataxia outcome measures
- Scale for the assessment and rating of ataxia (SARA)
- international cooperative ataxia rating scale (ICARS)
- Friedrich’s ataxia rating scale (FARS)
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
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)
FARS
- sub scales- ataxia, ADLs, neurological examination
- 0-159 (higher score is more disability)
Postural stability outcome measures
- Clinical test of sensory interaction and balance
- sensory organization test
- push and release test
- retropulsive pull test
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
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
Functional balance outcome measures
- BBS
- DGI
- FTSTS
- Functional reach test
- TUG
Dynamic gait index
-8 walking tasks 0-4
-scored 0-24 (lower number is more dysfunction
<=19/24 is increased fall risk
FTSTS
> 13 seconds indicates balance dysfunction
Functional reach test
<15 cm = fall risk
