Extrapyramidal TractsName: Ali Al-Nasrullah

Learning Objectives

Identifying Pyramidal tract.

Identifying Extrapyramidal tracts origin, termination and function.

Explaining extrapyramidal disorders.

Explaining Parkinson disease.

Pyramidal Tract

It is consisted of 3 tracts, Anterior & Lateral Corticospinal tract and some of corticobulbar tract.

* While traveling form the cerebral cortex these fibers give the apperance of a pyramid on the upper part of the medulla.

They terminate in the anterior grey matter.

Function: Voluntary, fine & skilled movements of the body.

Other fibers than these 3 are named extrapyrimdal.

Extrapyramidal Tracts

Definition :

The descending spinal tracts which is concerned with motor functions other than pyramidal tract. They are considered as an indirect motor pathway.

Extrapyramidal Tracts They are consisted of a series of tracts:

Rubrospinal Tract.

Reticulospinal Tract, Dividid into 2 types:

A- pontine reticulospinal tract. (Medial)

B- Medullary reticulospinal tract. (Lateral)

Tectospinal Tract.

Vestibulospinal Tract.

Rubrospinal Tract

Originated from the red nucleus located in the mesencephalon

Terminate in the lateral column of spinal cord.

Function: Motor functions of skeletal muscles of the limbs, hands, and feet.

Reticulospinal Tract

A- pontine reticulospinal tract. (Medial & Excitatory)

Originated from pontine reticular nuclei in pons which terminate in the medial anterior column.

B- Medullary reticulospinal tract. (Lateral & Inhibatory)

Originated from medulla and terminate in lateral anterior column.

Function: It Facilitates extensor reflexes & Inhibits Flexor reflexes.

Tectospinal Tract.

Origin: Superior colliculus of midbrain.

Terminate in the Anterior Column.

Function: Motor function of the Skeletal muscles of the head and eyes in response to visual stimuli.

Vestibulospinal Tract

Origin: vestibular nucleus in medulla.

Terminate in the Anterior Motor Neuron.

Function: Motor function of muscle for maintaining balance in response to head movements

Extrapyramidal Disorders

They are also named disorders of the Basal Ganglia, because the basal ganglia were once considered to form a separate extrapyramidal motor system.

CAUSES OF EXTRAPYRAMIDALCAUSES OF EXTRAPYRAMIDAL DISORDERSDISORDERS

Drugs, Toxins, hereditary.

It can be divided into two classes:

Hyperkinetic & hypokinetic

Extrapyramidal Disorders

Hyperkinetic:

seen in such disorders as

Chorea (dance)

Athetosis (“without position”) :

Slow, writhing, continuous, wormlike movements of the distal parts of the extremities, which show bizarre posturing.

ballism (jump or throw), dystonia, tremor, and Huntington disease.

Extrapyramidal Disorders

Hypokinetic:

seen largely in Parkinson’s disease and Parkinson plus syndromes.

reduced facial expression (mask-like)

reduced blinking

reduced adjustments of posture when seated.

Extrapyramidal DisordersParkinsonism

Six features:

1. Rest Tremor, 2. Rigidity, 3. Bradykinesia, 4. Flexed posture, 5. Loss of postural reflexes (fall), 6. Freezing phenomenon

Tremor, rigidity, and flexed posture are referred positive phenomena.

Bradykinesia, loss of postural reflexes, and freezing are negative phenomena.

Rest Tremor

Present in the extremities, almost always distally

Rest tremor disappears with action but reemerges as the limb maintain a posture(at rest).

• Rest tremor is also common in the lips, chin, and tongue

• Rest tremor of the hands increases with walking

Stress worsens the tremor

Extrapyramidal Disorders

Parkinson’s disease

Who is this ?

Mohammed Ali ClayHeavy weight champion boxer

Extrapyramidal Disorders

Parkinson’s disease

Who is this ? Michael J. Fox„Back To The Future“

BBasal ganglia :

caudate, putamen & globus pallidus are named corpus striatum

Caudate &putamen are named striatum

globus pallidus & putamen are named lentiform nuclei

caudate putame

nglobus pallidus

Extrapyramidal Disorders

Parkinson’s disease• It is characterized as a resting tremor.

• Cause:

• Degenerating substantia nigra pars compacta (the region of dopaminergic neurons projecting to the substantia nigra).

• It’s still not known what causes this degeneration

• (1) rigidity, (2) bradykinesia, (3) tremor, and (4) Loss of postural reflexes (fall), Gait disorder (short steps).

• Autonomic findings: Constipation, postural hypotension, sweeting .

• % 20 - 40 At late stages dementia occure.

• By the time symptoms appear, the substantia nigra already has lost about 60% of dopaminergic neurons.

Extrapyramidal Disorders

Parkinson’s disease• Mean age at onset in both sexes is 55 years

(range: 20-80).

• Over 60 years of age risk of Parkinson’s disease is 1%

• Male/female = 3/2.

Extrapyramidal Disorders

Parkinson’s disease• DiagnosisDiagnosis

• Based on clinical findings and signs (The doctors information)

• CT or MRI brain scan to exclude other causes. Positron Emission Tomography may detect low levels of dopamine in the brain.

• But PET scanning isn't commonly used to evaluate Parkinson's because it's very expensive, not available in many hospitals, and only used experimentally.

Extrapyramidal Disorders

Parkinson’s disease• TreatmentTreatment

• Aimed at controlling symptoms.

• It includes pharmacotherapy, physiotherapy and surgery.

• Levodopa (Dopamine precursor) is the most effective drug, BUT 75% of patients have serious complications after 5 years of LD therapy.

• Dopamine agonists— bromocriptine, pergolide

• Deep brain stimulation is the main type of surgery for Parkinson’s disease

Extrapyramidal Disorders

Parkinson’s disease• Future Treatments:Future Treatments:

• Some researchers are hopeful that stem cell treatments or gene therapy will be helpful for people with Parkinson’s disease.

• Currently, research into stem cell treatments and gene therapy is only in its initial stages.

Summary• Pyramidal tract is consisted of 3 tracts, Anterior & Lateral Corticospinal tract

and some of corticobulbar tract.

• Extrapyramidal tracts is concerned with motor functions other than pyramidal tract. They are considered as an indirect motor pathway.

• Rubrospinal Tract. Reticulospinal Tract, Dividid into 2 types: A-pontine reticulospinal tract. (Medial) B-Medullary reticulospinal tract. (Lateral), Tectospinal Tract.,Vestibulospinal Tract.

• Extrapyramidal disorders can be divided into two classes: Hyperkinetic & hypokinetic

• Hypokinetic is seen largely in Parkinson’s disease and Parkinson plus syndromes.

• Rest tremor present in the extremities, almost always distally

• Degenerating substantia nigra pars compacta (the region of dopaminergic neurons projecting to the substantia nigra) It’s still not known how.

Refrences

Neurology and Neurosurgery Illustrated

by Kenneth W. Lindsay, Ian Bone, and Geraint Fuller 5th edition

Guyton And Hall Textbook of Medical Physiology 12th Edition

Disorders of the nervous system

By Alexander G. Reeves, M.D.

Rand S. Swenson, M.D., Ph.D.

Hauser RA et al; Parkinson Disease, Medscape, Jan 2013

http://www.brainandspine.org.uk/parkinsons-disease