Cerebellum and postural control

What is the role of the cerebellum?

-       Takes the intended movement and then takes the actual movement and then calculates the error between them. Once this error is calculated, the cerebellum fines tune the motor movement

-       Helps fine tune muscle tone, coordination, balance and posture

What are the three roles of the cerebellum?

Anterior, posterior and floccule nodular lobe

What are the 5 main motor functions?

• -       Co-ordination of motor movements

  -       Feedback control of motor function- corrective

  -       Dampening functions-prevents under or overshooting

  -       Predictive function-accuracy of movement

  -       Equilibrium function

Where is the Vestibulocerebellum and what is the function?

-     Anatomically is the flocculonodular lobe. Has a function in balance and eye movements, it is the vestibulospinal tract

Where is the cerebrocerebellum and what is the function?

-       Anatomically found in the cerebellar hemispheres. More related to motor planning and coordination

Involved in preparation anticipation of movement and feed forward mechanism

Where is the spinocerebellum and what is the function?

-       Anatomically is the vermis- contains the homunculus for the trunk (in the vermis) and the limbs (in the para vermis). The vermis has a role in motor execution via the medial and lateral descending tracts. Plays a role in error correction

What is either side of the vermis?

Para vermis or the intermediate zones

What cerebellar nuclei is related to the vestibule cerebellum?

Vestibular nuclei

Where does the nuclei project to from the vestibulo cerebellum?

Oculomotor

What tract is related to the vestibulo cerebellum?

Vestibularspinal tract

What cerebellar nuclei is involved in sprinocerebellum (vermis)?

Fastigial nucleus

Where does the nuclei project to in the spin-cerebellum (versus) region?

Reticular nuclei

What tract does the spinocerebellum (vermis) relate to?

Reticulospinal tract

What cerebellar nuclei is involved in the intermediate hemisphere (paravermis)?

Interposed nucleus

Where does the nuclei project to in the intermediate hemisphere (paravermis)?

Red nucleus

What tract relates to the intermediate hemisphere?

Rubrospinal tract

What cerebellar nuclei is involved in the cerebrocerebellum region?

Denate nucleus

Where does the nuclei project to for the cerebrocerebellum region?

Thalamic nucleus

What tract is related to the cerebrocerebellum?

Motor cortex

how do patients present with a cerebellar small lesions?

-       produce no signs or only transient symptoms: small deficits are compensated for by other parts of the brain

How do patients with lesions of the cerebellar hemispheres present?

-       loss of muscular coordination & jerky, puppet like movements of the limbs on the ipsilateral side (same side as lesion)

How do lesions of the vermis present?

-       result in truncal tremor & gait ataxia (body sway while walking)

-       Truncal sway, dysmetria, dysdiadochokinesia (a condition that makes it difficult to perform rapid and altering movements), dysarthria, dizziness, tremor, nystagmus, hypotonia

-       D (dysdiadochokinesia) A(ataxia) N (nystagmus) I(intention tremor) S(speech) H(hypotonia)

What would you test for in a cerebellar clinical assessment?

• Gait ‘normal’ and struggle walking heel to toe

• Rebound in upper limbs (when you got to resist movements, limbs will fly up)

• Pendulum swing in lower limbs

• Drift-upper and lower limbs (when a patient goes to raise their hands, they will drift away)

• Finger-to-nose test

• Heel-shin test

• Eye-nystagmus

• Fingers-thumb test

• Dysdiadochokinesia

• Lying-sitting-truncal ataxia

• Tremor

• Past pointing

• Speech

• Hypotonia

• Rhombergs

Define postural orientation

-       Involves co-ordination of movement strategies to stabilise the COM during both self-initiated and externally triggered disturbances of stability

Define postural stability

the ability to control the COM relative to the BOS. Involves co-ordination of movement strategies to stabilise the COM during both self-initiated and externally triggered disturbances of stability

Define the Bobath concept

a rehabilitation approach used to treat individuals with movement, tone, and functional impairments due to central nervous system lesions, focusing on promoting motor learning and efficient motor control

Define stability limits

The area which an individual can move their COM and maintain their balance without changing their base of support

What is steady state motor strategy ?

-       the ability to control the COM within BOS during quiet stance or relative to the BOS in locomotion (predictable)

What is reactive balance control?

Recovering a stable position of COM following a perturbation e.g after being pushed/tripping (during quiet stance and locomotion). Onset, sequencing, amplitude, adaptation

What is the predictive balance control?

-       proactive/Anticipatory balance- activating the postural system in advance of a potentially destabilising movement to minimise instability. Volitional

What are APAs?

• Anticipatory postural adjustments

• Feed-forward for expected postural disturbances

• Predictable

• Relate to the lateral reticulospinal tract

What are CPAs?

• Compensatory postural adjustments

• Feedback for unexpected postural disturbances

• Much more spinocerebellar tracts and VST

• Unpredictable and reliant on sensory information

What is predictive perturbation?

Anticipatory activates the balance system in advance of destabilising movement

What is reactive perturbation?

Recovering a stable COM following a perturbation

What is the ankle strategy?

•       Restores  COM to a position of stability through body movement centred primarily about the ankle / mid tarsal joints

•       Used most commonly in situations in which the perturbation to stability is small and the support surface is firm

•       Distal to proximal sequence

•       Use this strategy in response to smaller disturbances

What is hip strategy?

•       Controls motion of the COM by producing large and rapid motion at the hip joints with antiphase rotations of the ankles

•       Used to restore stability in response to larger & more rapid perturbations,

•       Used when the support surface is compliant, smaller than the feet, e.g. standing on a beam, or a mobile BOS.

•       Proximal to Distal sequence

•       Relies in abs and quads

What is the stepping strategy?

•       Initially believed that the stepping strategy was used solely in response to perturbations that moved the COM outside the base of support

• More recent research has found that in many conditions, stepping occurs even when the COM is well within the BOS

How can we test balance and postural control?

• Functional reach test

• The nudge test

• TUAG

• Compensatory stepping corrections

• Single leg stance

What is multiple sclerosis?

-       Damage occurs in the CNS to the myelin sheath affecting nerve conduction as a result of damage to the grey and white matter within the CNS. It is associated with the impairment of T cell function and B lymphocyte activity causing inflammation and nerve damage

-       Thought to be triggered by combination of environmental and acting in a genetically susceptible individual

What are the symptoms of MS?

-       poor balance, spasms stiffness, fatigue, weakness, mental health problems, eyesight problems, speech problems, cognition and bladder and bowel problems

 

What considerations need to be made for MS exercise?

-       Can be CNS or peripheral nerve problems

-       Weakness underlies tonal presentations

-       Commonly core work and stretching

What increases in likelihood with MS?

• Osteoporosis

• Depression

• Fatigue

• Cardiovascular diseases

Define ataxia

-       Unsteady and clumsy motion of the limbs or trunk due to a failure of the gross coordination of muscle movements

-       Three types of ataxia: Cerebellar, vestibular or proprioceptive

Features of cerebellar ataxia

-       Dysmetria

-       Tremor

-       Dysynergia

-       Visuo- motor changes

-       Wide based gait pattern

-       ↑ Postural sway

-       ↓ Motor learning

-       Vermis=bilateral

-       Hemispheres=ipsilateral

Features of sensory ataxia

•       High stepping gait

•       Dependent upon vision

•       Positive Rombergs

•       Excessive grip

•       Dysynergic movement

•       Very reliant on vision

Features of vestibular ataxia

•       Lean backwards or sideways

•       Staggering gait

•       ↓ righting reactions

•       Dependent upon vision

•       ↓ head and trunk mvt

•       Vertigo and nystagmus

•       Poor midline orientation

Define Friedrich’s ataxia

Degeneration of dorsal columns, spinocerebellar tracts and denate nucleus

Affects balance, speech, walking and sensory and non neurological features (cardiac/bladder bowel/MSK

Progressive

Define autosomal dominant and recessive ataxias

Hereditary ataxias

Neurodegenerative diseases

Gait ataxia, cerebellar signs, reduced balance and gait, dysarthria, dysphagia, oculomotor signs, nystagmus, reduced saccades, fatigue