The Cerebellum and Associated Presentations

Is the cerebellum infratentorium or supratentorium?

infratentorium

Functions of the cerebellum

- regulation of movement, postural control, and muscle tone

- error correcting mechanism

- the comparator! takes plan, compares to action, makes sure match. allows for feedback in real time

The cerebellum contributes to

- walking and sitting balance

- limb co-coordination

- eye movement

- speech

Does the cerebellum take from ascending, descending, or both?

both pathways.

descending = motor plan

ascending = feedback

Are cerebellar impairments contralateral or ipsilateral?

ipsilateral

Superior peduncle

output to cerebral cortex; efferent

Middle peduncle

input from pontine nuclei; afferent

Inferior peduncle

input from spine, reticular formation, vestibular nuclei; afferent

Spinocerebellum

- where most comparison occurs that allows us to see motor plan and then make changes

- take proprioceptive input to anticipate where body needs to go, and then we can make adjustments so the motor plan is accurate

Cerebrocerebellum

- involved in planning and initiation of movement

- before the movement planning

- there are some purely cognitive functions too that we don't really have to worry about in this class

Vestibulocerebellum

- where vestibular processing occurs

- input from occipital lobe and vestibular nuclei

- coordinate VOR, head on neck movement, ocular movements

- help body align self to stay upright

Spinocerebellum effects on function

- hypotonia

- impaired adaptive motor trunk-limb coordination

- ipsilateral impairments

Cerebrocerebellum effects on function

- abnormal timing of movement

- decomposition of movement

- impaired independent limb coordination (eye-hand, eye-foot)

- unnatural movement pattern

Vestibulocerebellum effects on function

- balance and gait impairments

- nystagmus

- vertigo, dizziness, nausea/vomiting, oscillopsia, anxiety

Ataxia

- loss of muscle coordination

- can affect gait, posture, or limb movements

- gait ataxia: widened base of support, arms at high guard, and unsteady, staggered steps

- affects rate, rhythm, and timing of responses

Asthenia

- global, profound weakness

- generalized muscle weakness in the extremities and/or trunk

- lack of energy to move

Dysarthria

- creates "scanning speech"

- less intelligible speech

- lacks normal melodic quality (natural rise and fall)

- quality is slow and slurred with impaired melodic quality

Dysdiadochokinesia

- impaired ability to perform rapid alternating movements

- movements become irregular with reduced ROM

- examples: brushing teeth

Dysmetria

- inability to judge the distance necessary for movement; can also include force and speed of movement as well

- hypermetria (overestimation)

- hypometria (underestimation)

Dyssynergia

- an impairment where movement is performed in a sequence of components rather than a smooth, single motion

- fractionated movement; can't do motion smoothly and with synergistic pattern (abnormal)

Hypotonia

- decreased muscle tone

- muscle may feel soft and flaccid

- diminised DTRs

- "floppy"

Nystagmus

- rhythmic, quick, oscillatory back and forth movements of the eyes

- involuntary drift, followed by an immediate corrective return of the eyes to their target

Rebound Phenomenon

- the inability to stop motion when resistance is removed from an isometric contraction

- over correction / over shooting

Tremors

- involuntary oscillatory movement resulting from contractions of opposing muscle groups

- resting: occurs without moving; common in those with PD

- intention tremors: occur during voluntary movements; think Huntington's disease

- postural tremors: back and forth movement of the body while standing; constantly moving; chorea

Causes of cerebellar dysfunction

- CVA --> ischemic vs. hemorrhagic; different arteries include SCA, AICA, PICA, basilar, vertebral

- tumors

- autoimmune: multiple sclerosis can attack the myelin in the cerebellum

- toxins

- development disorders: cerebral palsy and chiara malformation

- trauamatic brain injury: can effect any part of the brain

- infections

- hereditary degeneration

Toxins

- medications: antiepileptics, sedatives, some chemotherapies

- B6 vitamins: can eat as much in diet and have no toxicity, but toxin comes from supplements

- heavy metal poisoning: lead, mercury (from seafood --> tuna, swordfish)

- alcohol: acute is temporary, chronic is permanent

Infections

- viral: chicken pox, HIV, lyme disease

- bacterial: meningitis, encephalitis

Hereditary degneration

- spinocerebellar degeneration

- Friedreich's Ataxia

- Wilson's disease

Spinocerebellar degeneration

- autosomal dominant

- atrophy of the spinocerebellum

- term referring to a group of hereditary ataxias

Friedreich's ataxia

- autosomal recessive

- development in teenage years

- slow accumulation of iron in the CNS

- occurs in late childhood into teens

Wilson's disease

- autosomal recessive

- accumulation of copper in the brain, liver, and other organs

- can be treated with medication