NeuroTeach 10 - Cerebellum Part II

The dysfunctional little brain!!!

Part II

“regulates ‘rate, range, and force’ of movement”

Dutch anatomist Lodewijk 'Louis' Bolk (1866–1930)

2) Cerebellar tremor

- intention (active, kinetic, or terminal) tremor - increase in amplitude approaching to target normal (1) cerebellar (2) PD (3) ET (4)

3) Cerebellar tremor - intention (active, kinetic, or terminal) tremor - increase in amplitude approaching to target - 1st proximal muscles

4) Cerebellar tremor

- intention (active, kinetic, or terminal) tremor - increase in amplitude approaching to target - 1st proximal muscles

5) Cerebellar outflow pathway tremors

- postural tremor of the outstretched limbs, may also occur - 1st proximal muscles - when severe, can have myoclonic features - rubral tremor (cerebellar outflow tremor)

6) Cerebellar postural tremor - postural tremor of the outstretched limbs, may also occur - 1st proximal muscles

7) Cerebellar postural tremor

- postural tremor of the outstretched limbs, may also occur - 1st proximal muscles

8) Finally, ataxia

What is cerebellar ataxia? “varying degrees of dyssynergia, dysmetria, lack of agonist-antagonist coordination, and tremor” - unspecific - sensory ataxia ➡️ worse w/ eyes closed

9) Head titubation - axial hypotonia - slow-frequency cerebellar outflow tremor

10) Head titubation

- axial hypotonia - slow-frequency cerebellar outflow tremor

11) Cerebellar ataxic gait

“Wide based, reeling, careening (drunken sailor)” - inability to walk tandem - step length varies unpredictably - turning may bring out a stagger - acute alcohol intoxication

12) Tandem gait paradigm

“dysmetria, hypometria, hypermetria, and inappropriate timing of foot placement” -correlated w/ symptom severity & quantitative balance & gait parameters -cerebellar, sensory ataxia, vestibulopathy

13) Cerebellar gait observations

Unilateral lesions - deviation of head&body toward affected side - when standing, there is an inclination to fall - when walking a tendency to deviate, toward the side of the lesion - decrease of the normal pendular movement of the arm

14) Cerebellar homunculus

vermis lesions - not able to stand erect and may fall either backward or forward - gait is staggering, reeling, or lurching in character, without laterality

15) Cerebellar fits

decerebrate rigidity episodes because of brainstem dysfunction due to mass effect from cerebellar lesions - EEG variable amplitude diffuse asynch slow waves - noncortical - misdiagnosis, wrong therapeutic intervention

16) Cerebellar mutism

- complication of posterior fossa surgery, especially in children - 24% medulloblastoma - dentate-thalamo-cortical tracts - neurocognitive outcome is not favorable

17) Cerebellar writing

- macrographia, characters become larger - long writing time - variable velocity - deviation&shape pen tip > finger/wrist

18) Cerebellar drift

“drifts mainly outward, either at same level, rising, sinking” - accentuated by raise&lower arms or tapping wrists - ipsilateral 3 drifts cerebellar (out) pronator (Barre’s sign, ⬇️, pronation) parietal (contralateral, up&out)

19) Nystagmus

- vestibulocerebellar pathways “often result from involvement of the connections of the cerebellum with other centers rather than actual cerebellar dysfunction”