Pyramidal and Extrapyramidal disorders

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Pyramidal and Extrapyramidal disorders

• Dr.Kayed
• CNS Module- week 3

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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
  lateral corticospinal tract. Fibres that do not
  decussate descend as the anterior corticospinal
  tract.

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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

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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

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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

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Clonus
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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.

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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

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The function of the Extra-pyramidal system
Function Dysfunction
1. Regulation and integration of voluntary motor activity Involuntary motor activity rhythmic regular (static tremor) Dysrhythmic and irregular (chorea, athetosis, dystonia)
2. Regulation and maintenance of muscle tone Hypertonia or rigidity
3. Regulation and maintenance of emotional associative movement Bradykinesia, mask face, infrequent blinking, loss of swinging during walking.
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There are two main categories of Extra-pyramidal
disorders

• Akinetic rigid syndrome (Parkinsonism)
• Dyskinesias
• Tremor
• Chorea
• Myocolonus
• Tics
• Dystonia

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Tremor

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

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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.

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Tremor syndromes
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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

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Causes of chorea

• Causes
• Hereditary huntingtons disease
• Birth injury Kernicterus
• Rheumatic Sydenhams chorea
• Pregnancy chorea gravidarum
• Vasculitic
• Thyrotoxicosis
• Drugs L-Dopa

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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

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Dystonia

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

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Myoclonus

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

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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)

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CEREBELLAR DYSFUNCTION
Cerebellar lesion Signs
Posterior(Flocculo-nodular lobe Archicerebellum) Eye movement disorders Nystagmus Vestibulo-ocular reflex (VOR)Postural and gait dysfunction
Midline(Vermis paleocerebellum) Truncal gait ataxia
Hemisphere(Neocerebellum) Limb ataxia Dysmetria, Dysdiadochokinesis, "intention" tremor Dysarthria Hypotonia