Parkinson's Disease

Question 1

What are upper motor neurons?

Answer 1

Neurons that have their soma in the cortex and their axon descends to the brain stem or spinal cord.

Question 2

What is the pyramidal tract?

Answer 2

It is another word for upper motor neurons, it encompasses 2 tracts:

1) corticospinal tract - neurons running from the cortex to the spinal cord
2) corticobulbar tract - neurons that run from the cortex to the brain stem

Question 3

What is the extrapyramidal tract?

Answer 3

Neurons involved in modulating movement (coordinating, initiating, controlling rate and force of movement). These neurons modify motor neuron signals indirectly (they are polysynaptic).

Question 4

What are lower motor neurons?

Answer 4

These neurons have their soma in the brain stem or spinal cord and they innervate skeletal muscle.

Question 5

Generally speaking, what type of disorder is Parkinson’s Disease?

Answer 5

It is a neurodegenerative disease, in fact it is the second most common neurodegenerative disease.

Question 6

Who is most often affect by Parkinson’s Disease? When do symptoms normally appear?

Answer 6

Men are more often affected and symptoms normally appear in 50s.

Question 7

What causes Parkinson’s Disease?

Answer 7

• mostly idiopathic
• known/suspected cause:
• – genetics
• — atherosclerosis
• – excessive accumulation of oxygen-free radicals
• – viral infection
• – head trauma
• – chronic use of antipsychotic medications
• – environmental exposures

Question 8

What are the four cardinal signs of Parkinson’s Disease?

Answer 8

1) tremors (usually resting tremor, unilateral)
2) rigidity (resistance to passive movement, may have jerky movement in response to passive movement = cogwheel rigidity)
3) bradykinesia (slow movement)
4) postural instability (loss of postural reflexes, ex. stand with head bent, shuffling gait)

Question 9

What are a few more signs and symptoms of Parkinson’s Disease?

Answer 9

• dementia
• micrographia
• blank expression
• dysphonia (soft voice)

Question 10

How is Parkinson’s disease diagnosed?

Answer 10

Patient exhibits 2 of the 4 cardinal signs.

Question 11

What happens in Parkinson’s Disease? What is the pathophysiology?

Answer 11

• neurons in the substantia nigra that produce dopamine are destroyed
• this causes a decrease in dopamine stores, causing an neurotransmitter imbalance in the corpus striatum (more Ach than dopamine)
• voluntary movement is affected via the extrapyramidal tract
• 4 cardinal signs are produced

Question 12

What is the corpus striatum?

Answer 12

It is part of the extrapyramidal tract. Here neurotrasmitters are key to controlling body movements. It is connected to the substantia nigra.

Question 13

What are dopamine and aceytylcholine and what affects do they have in the corpus striatum?

Answer 13

They are neurotransmitters. Dopamine is inhibitory, acetylcholine is excitatory.

Question 14

How is Parkinson’s disease treated?

Answer 14

no cure, drugs used to manage symptoms:

• levodopa - converted in body to dopamine, restores Ach dopamine balance but loses affect after 5-10 years
• anticholinergic drugs - counteract the action of Ach to restore balance
• amantadine - an antiviral, unknown mech. but decreases symptoms in early Parkinson’s
• monoamine oxidase (MAO) inhibitor - inhibits dopamine breakdown to restore balance
• dopamine agonist - use when levodopa loses affect