THE CEREBELLUM ANATOMY: the cerebellum is formed of 2 main parts: n 1. A midline central structure, known as the vermis. n 2. Two lateral cerebellar hemispheres. *cerebellum can be divided: 1 - Focculo-nodular lobe. 2. Anterior lobe. 3 - Posterior lobe. n
Anterior lobe Paleocerebellum Posterior lobe Neocerebellum Foocculo-nodular lobe Archicerebellum
n Archicerebellunm lobe): (flocculo-nodular
n Paleo-cerehellum (anterior lobe):
n Neocerebellum (posterior lobe):
Blood Supply n The cerebellum is supplied by: n Superior cerebellar artery (branch of the basilar artery). n Anterior inferior cerebellar artery (branch of the basilar artery). n Posterior inferior cerebellar artery (branch of the vertebral artery).
Cerebellum Syndromes n I. Archicerebellar syndrome:
n II. Neo-cerebellar syndrome: There is incoordination of voluntary motor activities
ATAXIA n Definition: Incoordination of voluntary motor activity with or without disequilibration in the absence of motor weakness.
Cerebellum Ataxia n Causes of Cerebellar Ataxia: n I. Herido-familial: 1. Friedreich's ataxia. n II. Symptomatic : Congenital n Infective n Vascular n Toxic n 2. Marie's
5. Neoplastic 6. Demyelination 7. Metabolic III. Idiopathic:
Clinical picture of Cerebellar Ataxia I. Incoordination of movements of different muscles in the form of: a)Nystagmus in the eyes. b) Staccato speech. c) Nodding of the head. d) Titubaiion of the trunk. e) Kinetic tremors of the limbs.
II. Hypotonia and hyporeflexia of the affected muscles. III. Gait disturbance: Wide base or drunken gait in archicerebellar lesions. IV. Positive tests: used by the neurologist to detect cerebellar ataxia.
TESTS OF CEREBELLAR ATAXIA 1. Finger to nose test:
2. Finger to doctor's finger test: you may found a) Decomposition of movement. b) Kinetic intention tremors c) Dysmetria in the form of hypermetria or hypometria
4. Rebound phenomenon:
5. Heel to knee test
HERIPO-FAMILIAL ATAXIAS I. Friedreich's Ataxia 1. It occurs in the 1 st decade of life. 2. Gradual onset and slowly progressive course. 3. Positive family history is common as it is inherited as an autosomal recessive disease.
4. Pathologically there is degeneration of: - Cerebellum specially the archicercbcllum & the spinocerebellar tracts. - Pyramidal tracts. - Posterior columns. - Peripheral nerves. P. N
II. Marie's Ataxia 1. It occurs in the 2 nd and 3 rd decades of life. 2. Gradual onset and slowly progressive course. 3. Pathologically there is degeneration of: - Cerebellum specially the neocerebellum (dentate nucleus)
- It presents with progressive manifestations of neocerebellar degeneration. - Mental impairment, ocular nerve paralysis and extrapyramidal syndromes are occasionally present.
SENSORY ATAXIA n Definition: - It is ataxia due to loss of the proprioceptive (deep) sensations, at any point in their pathway.
n Causes : 4. Medial lemniscus : brain stem lesions. 5. Thalamus : thalamic syndrome. 6. Cortical sensory area : parietal lobe lesions.
n Rhomberg’s Test :
VESTIBULAR ATAXIA n Definition : - It is ataxia due to lesions of the vestibular division of the eighth nerve.