Parkinson's

Question 1

What are the causes of Parkinson’s disease?

Answer 1

Genetic - mutation of the gene that encodes for a-synuclein and is associated with Lewy bodies

Environmental factors - MPTP exposure is a neurotoxin that kills dopaminergic neurons

Idiopathic occurs with age - in >50 or >65 year olds

Question 2

What can reduce the risks of Parkinson’s?

Answer 2

Moderate consumption of coffee, alcohol and smoking

Question 3

How does drug-induced dementia occur and what should be done to stop it?

Answer 3

First generation antipsychotics or other drugs block dopamine receptors

Sodium valproate causes parkinsonian tremor

Stop the drugs, some effects of tardive dyskinesia may not be reversible

Question 4

What are the motor symptoms of Parkinson’s?

Answer 4

Bradykinesia - slow movement, shuffling gait

Rigidity - increase in muscle tone

Cog-wheeling - rigidity with tremors

Resting tremors

Postural instability

Question 5

What are the autonomic symptoms of Parkinson’s?

Answer 5

Postural hypotension

Sialorrhoea - failure to remove or retain excess saliva

Question 6

What are the cognitive symptoms of Parkinson’s?

Answer 6

REM sleep disorder

Hallucinations

Question 7

What are the types of dementia in Parkinson’s and when is their onset?

Answer 7

Dementia with Lewy bodies (early onset)

Parkinson’s dementia (Late onset)

Question 8

How do Lewy bodies cause dementia?

Answer 8

Deposits of a-synuclein in nerve cells in the brain

Prevents sufficient functioning of neurotransmitters

Question 9

How is Parkinson’s diagnosed?

Answer 9

Brain bank criteria

Imaging- for loss of dopaminergic neurons

Consideration of other factors that could cause it e.g. drugs or comorbidities

Question 10

What is the brain bank criteria?

Answer 10

Step 1:
Bradykinesia and rigidity, rest tremor or postural instability

Step 2:
exclusion criteria

Step 3:
Good response to L-dopa

L-dopa response >5 years

Question 11

What are benefits of using a decarboxylase inhibitor

Answer 11

Benserazide - madopar

carbidopa - sinemet

Prevent the breakdown of levodopa in the periphery

Allows dopamine to cross the BBB

Lower dose of levodopa can be used, as more of it will be available in the BBB

Reduces nausea, arrhythmias and hypertension caused by peripheral dopamine

Question 12

What counselling should be given for taking levodopa?

Answer 12

Take it 30 minutes before food

Have a low protein diet, as protein reduces the absorption

Question 13

Why is it difficult to treat tremors with levodopa?

Answer 13

It is a difficult motor symptom to treat at low doses

Question 14

What are the downsides of dopamine agonists?

Answer 14

It comes with postural hypotension which can be a symptom of Parkinson’s

It is less effective at managing motor symptoms so less improvement to quality of life

More adverse reactions

Impulse control disorders

Question 15

When are MOAb inhibitors given?

Answer 15

In young people who do not want to be on levodopa

As a levodopa-sparing method in late PD

Question 16

What is end of dose deterioration?

Answer 16

Disease progression and a loss of capacity to store dopamine

So there is less on time with levodopa

Question 17

What are the causes of end of dose deterioration?

Answer 17

Long-term levodopa therapy

Dopamine isn’t being stored due to less dopaminergic neurons with the progression of disease

Effects start to wear off at an earlier point

Delay in returning to on time due to GI malabsorption and competition with amino acids at the BBB

Question 18

What are the issues and risk factors with levodopa-induced dyskinesia?

Answer 18

Risk of falls and weight loss due to muscle waste

The severity of dyskinesia is associated with depression

Risk factors: low body weight, high doses and young age

Question 19

How is levodopa therapy optimised?

Answer 19

Levodopa-sparing therapy

Smaller, more frequent doses

Using MR preparation