Cerebellum lecture 3 DR KHURAM SHAHZAD KHAN ASSISSTANT

Cerebellum lecture: 3 DR. KHURAM SHAHZAD KHAN ASSISSTANT PROFESSOR PHYSIOLOGY

Cerebellum Lesions 2 21 February 2021

Cerebellar Hemispheric Lesions deficit. lesions cause no paralysis or sensory When not moving , there are no externally obvious signs. However , upon physical examination , signs such as hypotonia and pendular reflexes can be elicited. . 21 February 2021 Cerebellar 3

Once the patients attempts movement , ataxia appears. What is ataxia ? Ataxia is incoordination of due to errors in the rate , range , force and direction of movement. With circumscribed lesions , the ataxia may be confined/localized to only one part of the body

The Difference Between Lesions of the Cerebellar Cortex & Lesions of DCN only the cortex of the cerebellum is involved , the movement abnormalities gradually disappear as “ compensation ” occurs. However , lesions of the DCN produce more generalized defects , and abnormalities are permanent. For this reason , care should be taken to avoid damaging the DCN when surgery is undertaken to remove a tumor involving part of the cerebellar cortex. 21 February 2021 If 5

A/ Hemispheric Lesions I/Ataxia 6 21 February 2021 (lack of coordination of muscle movement ) , which is manifested by (1) Wide-based , unsteady “ drunken , or staggering “ gait. (2) Scanning speech (3) Dysmetria ( also called Past-Pointing ) : attempting to touch an object with a finger results in overstretching to one side or the other this promptly initiates a gross correction action ( corrective action ) , but the correction overshoots to the other side Consequently , the finger oscillates back and forth. This oscillation is the (4) “ Intention Tremor ” , which is characteristic of cerebellar disease. This cerebellar tremor , unlike that of Parkinson’s disease , is absent at rest.

7 21 February 2021 B/ Flocculonodular Lobe Lesions Midline cerebellar tumors in children , arising from the “ Nodule ” , early in their course (& before affecting the rest of the cerebellum) , damage first the Flocculonodular lobe. Such a child is afraid ( & reluctant ) to stand erect and move without support. This is because if he tries to walk , he does so in a staggering fashion on a broad base , & tends to fall. Moreover , selective Flocculonodular lobe lesions may cause vertigo