Download Cerebellar system and diseases

Cerebellar system and diseases
Balance & Equilibrium
Cerebellum
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Coordination of movement
Control of gait, posture (Balance )
Control of muscle tone (Motor control )
Cognitive functions
– Attention
– Emotions
– Language
Motor coordination
 Cerebellum does not initiate movement
 It contributes to coordination, precision, and accurate
timing.
 It receives input from sensory systems and from other
parts of the brain and spinal cord,
 It integrates these inputs to tune fine motor activity.
Because of this fine-tuning function,
Cerebellar lesions produce disorders in fine movement,
equilibrium, posture, and motor learning.
4 Cerebellar nuclei& neurons
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Basket cells-inhibitory
Stellate cells-inhibitory
molecular
Golgi cells-inhibitory
Granule cells-excitatory (Glutamate)
Purkinje cells; inhibitory (GABA)
 Dentate nucleus
 İnterpositus nucleus
 Fastigius nucleus
emboliform
globose
granular
Intrinsic Fibers
– Mossy fibers
These fibers carry impulses from the inferior
peduncle from spinocerebellar pathways,
olivocerebellar pathways.
– Climbing fibers
They carry impulses from the middle cerebellary
peduncle. They carry impulses from the cortex
and projects to the cortex.
Phylogenetically..
• Flocculo-nodulus ARCHICEREBELLUM –
related with vestibular nuclei
• Anterior lobes-PALEOCEREBELLUMspinocerebellar pathways
• Posterior lobes- NEOCEREBELLUM – cerebellopontin pathways
Vestibulo-cerebellum
• Flocculo-nodulus receives special
proprioceptive impulses from the vestibular
nuclei (located in pons and the bulb)
Equilibrium and balance , spatial orientation.
Any lesion will cause ataxia , gait disturbance,
Walking difficulty
Spinocerebellum
• Vermis, The medial zone of the anterior lobes
• It receives proprioceptive input from the
spinocerebellar tract and from visual and
auditory systems.
• It sends fibres to deep cerebellar nuclei that,
in turn, project to both the cerebral cortex and
the brain stem, thus providing modulation of
descending motor systems; POSTURE,
MUSCLE TONE.
Neocerebellum
• Posterior lobes receive afferents from cortex
through corticopontine pathways.
• It projects to the cortex via the dentate
nucleus. Its projections are to the cerebral
cortex through nucleus ruber, thalamus.
• In association with the differentiation of
skeletal muscle this part is the largest in
humans.It coordinates skilled movements.
• Many projections (mainly the purkinje cell)
relay on deep cerebellary nuclei (mainly
dentate nuclei) and then projects.
• Contrary, Floculo-nodulus directly projects to
vestibular nuclei.
Clinical manifestations of cerebellar
dysfunction
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Muscular coordination
Equilibrium
Locomotion
No weakness
Initiation of movement delays.
Relaxing delays.
Contractions are irregular, intermittent.
Speech disturbances
Features with regard to lobes
Posterior lobe
(neocortex)
Anterior lobe
(paleocortex)
Flocculo-nodulus
(archicortex)
Ataxia
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Nystagmus
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Intentional tremor
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Hyptonia
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Rebound
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Dysmetria..
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Dysmetria
Loss of ability to gauge
• the distance
• Speed
• Power of movement
The act may be carried out with too little or too
much power.
The act may stop before the goal is reached
or overshoot.
dysdiadokokinesia
• Disturbance of reciprocal innervationcoordination of agonist-antagonist muscles.
• İmpairment of rapid alternating muscles.
Hypotonia
• The body parts may be extended or flexed to
extreme positions as the muscle tonus is
decreased (flask).
Intentional tremor
• Tremor is not observed at rest, but during
reaching a target tremor becomes established.
Diferential diagnosis
• Resting tremor (parkinsonian)
• Postural tremor (essential , drugs)
Speech in cerebellar diseases
• Explosive
• Slurred
• As if drunken
Disease
Hereditary cerebellar diseases
• Friedrich ataxia
• Spinocerebellar ataxia’s
Acquired cerebellar diseases
• Vascular (Wallenberg syndrome, SCA infarct)
• Degenerative (multisystem atrophies)
• Demyelinating (Multipl Sclerosis)
• Toxic-metabolic (Alchohol abuse, diphenyl
hidantion chronic use)
• Neoplastic, paraneoplastic (cerebellar neoplasms)