Cerebellarsystemanddiseases Balance & Equilibrium
Cerebellum • Coordination of movement • Control of gait, posture (Balance ) • Control of muscle tone (Motor control ) • Cognitive functions • Attention • Emotions • Language
Motor coordination • Cerebellumdoes not initiatemovement • Itcontributes 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 finemotor activity. Because of this fine-tuning function, Cerebellarlesionsproduce disorders in fine movement, equilibrium, posture, and motor learning.
4 Cerebellarnuclei& neurons • Basket cells-inhibitory • Stellatecells-inhibitory • Golgicells-inhibitory • Granulecells-excitatory (Glutamate) • Purkinjecells; inhibitory (GABA) • Dentatenucleusemboliform • İnterpositusnucleus • Fastigiusnucleusglobose molecular granular
IntrinsicFibers • 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-PALEOCEREBELLUM- spinocerebellar pathways • Posterior lobes- NEOCEREBELLUM – cerebello-pontin pathways
Vestibulo-cerebellum • Flocculo-nodulusreceivesspecialproprioceptiveimpulsesfromthevestibularnuclei (located in ponsandthebulb) Equilibriumandbalance , spatialorientation. Anylesionwillcauseataxia , gaitdisturbance, Walkingdifficulty
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.
Clinicalmanifestations of cerebellardysfunction • Muscular coordination • Equilibrium • Locomotion • No weakness • Initiation of movement delays. • Relaxing delays. • Contractions are irregular, intermittent. • Speech disturbances
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 innervation-coordination 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 cerebellardiseases • Explosive • Slurred • As if drunken
Disease Hereditarycerebellardiseases • Friedrichataxia • Spinocerebellarataxia’s Acquiredcerebellardiseases • Vascular (Wallenbergsyndrome, SCA infarct) • Degenerative (multisystematrophies) • Demyelinating (MultiplSclerosis) • Toxic-metabolic (Alchoholabuse, diphenylhidantionchronicuse) • Neoplastic, paraneoplastic (cerebellarneoplasms)