Pyramidal and Extrapyramidal disorders

1. Pyramidal and Extrapyramidal disorders Dr.Kayed CNS Module- week 3

2. The pyramidal system • Fibres pass downwards from the motor cortical pre-central gyrus into the internal capsule, via the corona radiata. In the internal capsule fibres occupy the posterior third of the anterior limb and the anterior two-thirds of the posterior limb. • After descending through the internal capsule the corticospinal tract runs in the cerebral peduncles on the anterior apsect of the midbrain. The immediate posterior relation is the substantia nigra. • In the pons the fibres are scattered, but they regroup to form the pyramids on the anterior aspect of the medulla. • In the medulla most fibres decussate to form the lateralcorticospinal tract. Fibres that do not decussate descend as the anterior corticospinal tract.

4. Pyramidal tract disorder • Pyramidal tract disorders is also known as upper motor neuron syndrome that is caused by damage to the descending motor pathways. • The patient presents with consistent motor signs and symptoms • The Babinski sign • Hypertonic Spasticity • Clonus (oscillatory motor response to muscle stretching) • Hypereflexia (the reflexes are exaggerated) • A loss of the ability to perform fine movements • Muscle wasting result from prolonged non-use of the muscle

5. The Babinski sign • The normal response in an adult to stroking the sole of the foot is flexion of the big toe, and often the other toes. Following damage to descending upper motor neuron pathways, however, this stimulus elicits extension of the big toe and a fanning of the other toes

6. Spasticity • Spasticity is increased muscle tone, that will cause increase resistance to passive movement that increases with applied force until there is a sudden give at a certain tension. • Spasticity is probably caused by the removal of inhibitory influences exerted by the cortex on the postural centers of the vestibular nuclei and reticular formation

7. Clonus

8. A loss of the ability to perform fine movements • If the lesion involves the descending pathways that control the lower motor neurons to the upper limbs, the ability to execute fine movements (such as independent movements of the fingers) is lost.

9. Extra-pyramidal system • All fibers that influence the motor activity without passing through the pryamidal tract • Cortex • Basal Ganglia (caudate, putamen, globus pallidus, Subthalamic nucleus and substantia nigra) • Thalamus • Cerebellum • Red nucleus • Reticular nucleus

10. The function of the Extra-pyramidal system

11. There are two main categories of Extra-pyramidal disorders • Akinetic rigid syndrome (Parkinsonism) • Dyskinesias • Tremor • Chorea • Myocolonus • Tics • Dystonia

12. Tremor • Tremors is a rhythmic, involuntary, oscillatory movement of body parts • It is the most common movement disorder.

13. Classification of tremor • Tremors are classified as rest or action tremors. • Rest tremor occurs when the affected body part is completely supported against gravity. • Action tremors are produced by voluntary muscle contraction. • postural, isometric, kinetic tremors.

15. Tremor syndromes

16. chorea • Is continuous flow of involuntary irregular movement. The movements are rapid, jerky, non rhythmic and explosive that flit from portion of the body to another in random sequence. • It affects limbs and face and caused by lesion in caudate nucleus

17. Causes of chorea • Causes • Hereditary: huntington’s disease • Birth injury: Kernicterus • Rheumatic: Sydenham’s chorea • Pregnancy: chorea gravidarum • Vasculitic • Thyrotoxicosis • Drugs: L-Dopa

18. Athetosis • repetitive involuntary, slow, sinuous, writhing movements, which are especially severe in the hands. There are also elements of postural disturbance. Usually combined with chorea known as chorea-athetosis

19. Dystonia • Involuntary, twisting, sustained movement of the limb or head resulting in an abnormal posture.

20. Myoclonus • Brief, isolated, involuntary, random, jerk movement of a group of muscles. Intermittent with distinct pause between each movement.

21. Tics • Repetitive, stereotyped, semipurposeful movement. • Patient could willingly suppress them at expense of mounting inner tension • There are 2 types of tics • Simple tics of children: transient or chronic • Complex tics: Gilles de La Tourette syndrome (tics, vocalization, obsessive behavior)

22. CEREBELLAR DYSFUNCTION