Movement disorders

Question 1

Describe the pathophysiology of Parkinson’s disease

Answer 1

Progressive reduction of dopamine in the substantia nigra

Question 2

Describe the aetiology of Parkinson’s disease

Answer 2

Idiopathic

Question 3

Describe the clinical features of Parkinson’s disease

Answer 3

Core symptoms (usually asymmetrical):

1. Resting tremor
2. Rigidity
3. Bradykinesia

Other symptoms:

• Depression
• Sleep disturbance/insomnia
• Cognitive impairment

Question 4

Describe the investigation of Parkinson’s disease

Answer 4

• Clinical diagnosis, made by specialist (neurologist)

- Dopamine transporter (DaT) imaging can be used to support the diagnosis (this is rare)

Question 5

Describe the management of Parkinson’s disease

Does pharmacological therapy alter the natural history of the disease?

Are there any other management options?

Answer 5

Pharmacological therapy does not alter the natural history of the disease, but it does improve motor symptoms:

• Levodopa
• Dopamine agonists
• Monoamine oxidase-B inhibitors

Other management options:
- Physiotherapy

Question 6

What are the side effects of having too much dopamine (i.e. dose of anti-Parkinson’s medications is too high)?

Answer 6

Dyskinesias:

• Dystonia (excessive muscle contraction)
• Chorea (involuntary jerking movements)
• Athetosis (involuntary twisting/writhing motions, usually in hands and feet)

Question 7

Give some examples of causes of parkinsonism (other than idiopathic Parkinson’s disease)

Answer 7

“Parkinson’s plus” syndromes:

• Progressive supranuclear palsy (suspect if patient also presents with balance problems and gaze palsy)
• Multiple system atrophy (suspect if patient also presents with autonomic symptoms, e.g. urinary problems, postural hypotension)
• Dementia with Lewy bodies

Iatrogenic:
- Medications, e.g. antipsychotics

Question 8

Describe the mechanism of action of dopamine agonists and give one example of this class of drug

Answer 8

Stimulate dopamine receptors in the basal ganglia (they mimic dopamine)

Ropinirole

Question 9

Give 2 potential side effects of dopamine agonists

Answer 9

1. Behavioural changes (loss of inhibition)

2. Pulmonary fibrosis

Question 10

What is levodopa?

Why must it be combined with another type of drug?

Answer 10

Levodopa = synthetic dopamine

It must be combined with a peripheral decarboxylase inhibitor (e.g. carbidopa or benserazide) to stop it from being broken down in the body before it is able to cross the blood-brain barrier

Question 11

What is the name of the drug containing levodopa and carbidopa?

Answer 11

Co-careldopa

Question 12

What is the name of the drug containing levodopa and benserazide?

Answer 12

Co-benyldopa

Question 13

Describe the mechanism of action of monoamine oxidase-B inhibitors

Give 2 examples of drugs belonging to this class

Answer 13

Inhibit monoamine oxidase-B enzyme, which breaks down dopamine

Rasagiline, selegiline

Question 14

Which antiemetic is considered SAFE to use in Parkinson’s disease?

Why is this?

Answer 14

Domperidone

This is a dopamine antagonist BUT it does not easily cross the blood-brain barrier, and so the risk of developing EPSEs is minimal