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  • AEB/Lectures/Cerebellum
  • Review of gross features
    • Folia are parallel to each other (except for at the flocculus)
    • Flocculi are tucked in under the MCP, and next to pons. Sits in posterolateral sulcus
    • Posterolateral sulcus separates off the nodulus from the rest of the vermis
      • Bottom derpy part of the 4th ventricle is the nodule
    • (Next to nodule is uvula, which is also vestibular.)
    • Tonsils on bottom of posterior lobe
  • Most information leaves Cb via SCP, taking information from cerebellum up to the thalamus
  • MCP = fibres from pons
  • Spinocerebellar tracts are in ICP
  • Medullary climbing fibres enter the Cb via the ICP
  • Vestibular inputs come through MCP
  • Olive goes to the entire Cb
  • Paravermis = 1cm lateral to vermis

Case

A 36 year old man came to see to you because he had been experiencing headaches and vomiting. The headaches had been getting progressively worse over the past month and were precipitated by coughing and sneezing. He experienced nausea and vomiting independent of the headaches. For the past several weeks he had been unsteady on his feet with tendency to fall to the right and he admitted to occasional clumsiness with his right hand. General physical examination showed he was generally in good health with normal vital signs. He was alert, with normal fluent speech, no impairment of memory and he had no sensory disturbances. Neurological examination showed that there was some evidence of papilloedema and horizontal nystagmus upon lateral gaze. His muscle strength was intact and reflexes were normal but his gait was wide-based and when walking, he tended to veer to the right and was unable to stand on his right leg alone, particularly when his eyes were closed. Significant intention tremor was present in the right upper limb on finger to nose testing and in the right lower limb on heel to toe testing and he tended to overshoot the target(dysmetria). Alternating movements of his right hand were slow and disorganised (dysdiadochokinesia).


  • Nystagmus and balance problems indicate damage to what system? What parts of the cerebellum are involved in this system? Discuss how, based on the connections of this part of the cerebellum, nystagmus and problems with balance are likely to occur
    • Damage to flocculonodular lobe (vestibulocerebellum)
    • Nystagmus (involuntary eye movements)
      • Vestibulo-ocular reflex problem (concentrate gaze on one point); happens whether or not you're conscious (use it to test that they're alive)
    • Inputs to VCb include vestibular nuclei
    • Outputs of vestibulocerebellum = vestibulospinal tract and cranial nerves (via medial longitudinal fasciculus. The downward pathway
  • What is ataxia? What signs and symptoms above are indicative of ataxia in this patient? What parts of the cerebellum are involved in motor coordination? Discuss how, based on the connections of these structures, the ataxia may have occurred?
    • Ataxia is the loss of full control of bodily movements.
    • Targets = neocerebellum
    • When you first learn something, your cortex thinks about every step in the movement. Once you rehearse the movements over and over again, you're storing the information in the 1) basal ganglia and 2) the cerebellum
      • Basal ganglia stores fragments of movements (set of muscles)
      • Cb stores information about timing, force, sequence of the muscle contractions. Cb can adjust according to environment.
    • To tell the difference between the cortex and Cb in lesions - corticospinal lesions get paralysis/weakness. Cb lesions = timing, coordination of movements are unsynchronised. Basal ganglia lesions = involuntary movements (hemiballismus, chorea) or difficulty starting off and carrying out movements. No paralysis.
    • Decision to move loop: 1) association cortices 2) pontine nuclei 3) neocerebellum 4) dentate nucleus 5) thalamus (+red) 6) thalamus 7) cortex
    • Spinocerebellum = 1) inputs both about intention to move, and also sensory information from spinal cord 2) paravermis 3) interposed nucleus
  • Usually damage to spinocerebellum +
  • Blood supply: Superior cerebellar artery (top of hemispheres), AICA (flocculi, anterior regions), PICA
    • They share the supply to the deep nuclei
    • Vestibulocerebellar lesions might affect just flocculonodular lobe
      • Otherwise: injury to the "hemispheres" = neocerebellum and spinocerebellum = ataxia = decomposition of movements (have to do everything without your programming)
  • Are the signs and symptoms seen a result of damage to the right or left side of the cerebellum? Why?
    • Rightsided ataxia - therefore right cerebellum
  • How does the tremor in this patient differ from that seen in a patient with Parkinson’s disease?
    • Intention tremor, and the harder you try, the harder it is to do it. Parkinson's disease has a resting tremor. In Parkinson's when they concentrate on the movement, the tremor disappears
      • So concentrating = engage the cerebellum
      • Not concentrating = engage the basal ganglia

Notes

  • Ataxia = loss of motor coordination
  • Hypokinesia = loss (slowing) of movement
  • Papilloedema = swelling of the optic disk due to intracranial pressure
  • Cerebellar lesions = drunk = nausea, vomiting, loss of balance, can't walk a straight line
  • Eyes can override cerebellum to a point (basis of Rhomberg's test)
  • Cerebellum always affects the muscles on the ipsilateral side of the body (vestibulospinal tract, spinocerebellum are all ipsilateral. It's associated with contralateral corticopontine and corticospinal).
    • They fall over towards the side of the lesion. Alcohol
  • SCP lesion = no effects on balance, but does affect the coordination

Table to explain case

CerebellumTable.png