WEEK 3 - Nervous System II

Question 1

What defines Parkinson’s disease? (5)

Answer 1

Chronic, progressive neurodegenerative disorder affecting dopamine* producing neurons in the extrapyramidal system, impairing motor function, posture, muscle tone and smooth muscle activity

Question 2

How does the normal activity of dopamine and acetylcholine compare to that of someone with PD? (4)

Answer 2

*Dopamine - inhibitory
*Acetylcholine - excitatory
*They should be equal/balanced in a healthy individual, but in PD, there is diminished dopamine and an abundance of acetylcholine
*Failure to produce dopamine (controls movement), leading to excessive unopposed acetylcholine.

Question 3

Clinical manifestations of Parkinson’s disease (5)

Answer 3

RABIT
Tremor, rigidity, bradykinesia, akinesia, postural instability

Question 4

Define bradykinesia

Answer 4

Slow movements

Question 5

What imaging or diagnostic tests are typically normal in PD?

Answer 5

CT, MRI, cerebrospinal fluid analysis, and EEG

Question 6

What are the four main types of motor complications in PD treatment?

Answer 6

1. End-of-dose wearing off – Diminishing dopamine effect before the next dose.
2. Delayed/no “on” response – Due to delayed gastric emptying.
3. Start hesitation (“freezing of gait”) – Difficulty initiating movement.
4. Peak-dose dyskinesia – Involuntary movements when dopamine levels are high

Question 7

By the time PD is diagnosed, what percentage of dopaminergic terminals are still functioning?

Answer 7

Only about 20%

Question 8

Why must levodopa be combined with carbidopa?

Answer 8

Levodopa cannot be used by itself in the brain; carbidopa helps prevent its breakdown in the periphery, allowing more levodopa to reach the brain.

Question 9

How do dopamine replacement drugs work?

Answer 9

They stimulate presynaptic dopamine receptors to increase brain dopamine levels

Question 10

What are the adverse effects of high peripheral dopamine levels when levodopa is given alone? (5)

Answer 10

Confusion, involuntary movements, GI distress, hypotension, and cardiac dysrhythmias

Question 11

What are the contraindications for levodopa and carbidopa? (2)

Answer 11

Primary angle-closure glaucoma (can raise intraocular pressure).
Undiagnosed skin conditions (may activate malignant melanoma).

Question 12

What are the common adverse effects of dopamine replacement drugs like levodopa–carbidopa?

Answer 12

Palpitations, hypotension, urinary retention, depression, dyskinesia