Ataxia

3 structures: Superior, middle, inferior Function: connect cerebellum to brainstem Rules: Middle is afferent Superior is efferent Inferior is both

(Background slide from neuroanatomy) Peduncles (name them, function, rules)

Superior cerebellar artery, Posterior inferior cerebellar artery

2 arteries that serve the cerebellum

Scale of the assessment and rating of ataxia, Brief ataxia rating scale

2 most common ataxia rating scales

-CNS lesions (stroke, MS), -Heredetary, -Peripheral neuropathy

3 Causes of ataxia

-Flocculonodular lobe, -Anterior lobe, -Posterior lobe

3 anatomical lobes of the cerebellum

-cerebrocerebellum, -spinocerebellum (vermis and intermediate zone), -vestibulocerebellum (flocculo-nodular)

3 functional lobes of the cerebellum

-Coordination of compound multi-joint movement, -Balance and postural control, -Motor adaptation, -Cognitive functions

4 Cerebellum functions

Lack of voluntary coordination, difficulty regulating force, amplitude, direction, veolicty

Ataxia definition

Cerebellar dysfunction

Ataxia is a neurological sign indicative of what?

"Errored" movement

Ataxia simplified definition

Berg balance, Single leg stance, Tandem stance

Balance assessment tests

Dysfunction of the cerebellum

Cerebellar ataxia cause

Decreased coordination of voluntary panned movements, Decreased balance and eye control, Postural instability, Intention tremor, dysmetria, Dysdiadochokineisa, Writing abnormalities

Cerebellar ataxia symptoms

Ipsilateral

Cerebellum damage affects what side of the body?

-Plans and executes movement sequences, -Regulates and coordinates highly skilled movements, -Cognitive function

Cerebrocerebellum functions

Cortex to cerebellum, Information is modified, Back up to motor cortex, motor cortex to corticospinal tracts. Sensory info back up to cortex via dorsal columns. Loop starts over

Cerebrocerebellum loop

Dentate

Cerebrocerebellum nucleus projection

Balance, Gait, Rating scales, Observation of coordination

Clinical assessments of ataxia

Finger-nose-finger. Tapping tests , Heel-to-shin, Rebound

Coordination tests

Feeback is taking sensory information, allowing the cerebellum to modify it, and send back to the cortex to correct. Feedforward is sending information before any feedback has been given

Describe feedback/feed foward

Stepped farther, higher, and less accurate. Some participants have pretty good foot placement compared to control.

Describe leg placement in people with ataxia (compared to control in experiment)

They have variable step length, scissor in steps, and foot path deviation

Describe study results where ataxic patients walked on a treadmill

Normal people adapt quickly. People with cerebellar dysfunction adapt slowly or don't adapt

Describe study where the participants had to catch a ball and adapt to ball weight

Their figure 8's were more sloppy compared to the control with no dual task. Their figure 8's were garbage with dual tasking

Describe study where the participants had to draw figure 8s and perform another task

no they have a lot of overlap

Do the types of ataxia occur in isolation?

Reaching shoulder motion causes an interaction at elbow

Example of interaction torque

10 meter walk, 6 minute walk

Gait assessment tests

Decreases it

If you slow someone down, what is the effect on ataxia?

Input

Inferior peduncle function

Controlling agonist/antagonist movements appropriately when performing a motor tasks

Interaction torque simple description

Torque generated at a segment during movement because it is mechanically connected to another segment

Interaction torques definition

No. There is very little evidence to support this intervention. It increases the demands on muscles which are involved around interaction torques.

Many clinicians believe weighted vests are a good intervention. Are the correct? Why/why not

Input

Middle peduncle function

Decreased ability to control interaction torques, Decreased ability to adapt movements, Decreased ability to make automatic movements

Movement consequences of ataxia

-Exogenous substances, -Radiation poisoning, -Vitimin b12

Other rare causes of ataxia

Have them perform resisted isometric shoulder flexion and rapidly remove your resistance. People with ataxia cannot stop the movement quickly

Rebound test

Decreased ability to coordinate movement in the cerebellum

Regardless of the cause, what is the common cause of ataxia?

Dysfunction of dorsal columns, thalamus, cerebellum, or parietal lobes

Sensory ataxia causes

Decreased stability with eyes shut, AND: Decreased coordination, Decreased balance and eye control, Postural instability, Intention tremor, Dysmetria, Dysdiadochokineisa, Writing abnormalities

Sensory ataxia symptoms

subconscious proprioception to the cerebellum

Spinocerebellar tract information carried (not on the test, but it helps to understand the spinocerebellum better)

Integration of sensory and motor commands, Regulates posture, trunk movements, crude limb movements.

Spinocerebellum functions (in general, then specific)

-spinocerebellar tract carries info to the fastical nucleus, -projects it back to the thalamus, -projects back down the vestibulospinal tract. -loop restarts

Spinocerebellum loop

fastigal nucleus

Spinocerebellum nucleus

Fastigal nuclei

Spinocerebellum nucleus projections

Output

Superior peduncle function

Dysfunction of vestibular organs or vestibular nuclei

Vestibular ataxia causes

Nausea, vomiting. AND: Same as the other 2

Vestibular ataxia symptoms

Balance, posture, tone, equilibrium, Eye movements, reflexes.

Vestibulocerebellum function

vestibular system to the vestibular nuclei. 1 projection up to the extraocular nuclei. Other projection down the vestibulospinal tract

Vestibulocerebellum loop

vestibular nuclei

Vestibulocerebellum nucleus

Lateral: Control axial and proximal limb neurons for postural control. Medial: Control head/neck muscles in response to postural changes. Eye movement

Vestibulospinal tract info carried (not on the test, but it helps to understand the vestibulocerebellum better)

Velocity and acceleration

What are interaction torques dependent on?

There is a high degree of variability because some performed well and some did not

What can we conclude about the foot placement study about ataxia?

Decreases. Less interaction torques to regulate

What happens to ataxia when other body segments are stabilized? Why?

Deep cerebellar nuclei

Where do all outputs from the cerebellum originate?

They have lost proprioception from the dorsal columns

Why do people with sensory ataxia have decreased stability with eyes shut?