Parkinson's Flashcards
What is Parkinson’s disease
progressive neurodegenerative condition caused by degeneration of dopaminergic neurons in the substantia nigra
What is the classical triad of classical features for Parkinson’s disease?
- bradykinesia
- tremor
- rigidity
Are symptoms of Parkinson’s characteristically symmetrical or asymmetrical
asymmetrical
Describe the epidemiology of Parkinson’s disease
- around twice as common in men
- mean age of diagnosis is 65 years
Describe bradykinesia in the context of Parkinson’s disease?
- poverty of movement also seen, sometimes referred to as hypokinesia
- short, shuffling steps with reduced arm swinging
- difficulty in initiating movement
- difficulty in turning around when standing
- handwriting gets smaller
Describe the tremor seen in Parkinson’s disease
- most marked at rest, 4-6 Hz
- worse when stressed or tired, improves with voluntary movement
- generally asymmetrical
- typically ‘pill-rolling’, i.e. in the thumb and index finger
Describe the rigidity seen in Parkinson’s disease
- resistance to passive movement of the joint
- lead pipe
- cogwheel
Apart from the classical triad, what are some other characteristic features of Parkinson’s disease?
- depression
- postural instability
- masked facies
- stooped posture
- dementia, psychosis
- sleep disturbances and fatigue
Describe the features of drug-induced parkinsonism
- motor symptoms are generally rapid onset and bilateral
- rigidity and rest tremor are uncommon
What are Parkinson’s-plus syndromes
rare condition where neurones of various systems in the brain degenerate, including the basal ganglia
How is Parkinson’s disease diagnosed
- clinical - history and exam
- should only be diagnosed and managed by a specialist with expertise in movement disorders
How is Parkinson’s disease managed
- Levodopa usually combined with a decarboxylase inhibitor (e.g. carbidopa or benserazide)
- Dopamine agonists
- Monoamine oxidase B inhibitors
- catechol-O-methyl transferase inhibitor
Why is levodopa the most effective treatment of Parkinson’s
of the antiparkinson drugs, Levodopa is associated with the greatest improvement in symptoms and activities of daily life
Why is levodopa nearly always combined with a decarboxylase inhibitor
this prevents the peripheral metabolism of levodopa to dopamine outside of the brain and hence can reduce side effects
Give some common side effects of levodopa
- dry mouth
- anorexia
- palpitations
- postural hypotension
- psychosis
Give some adverse effects associated with difficulty in achieving a steady dose of levodopa
- end-of-dose wearing off: symptoms often worsen towards the end of dosage interval -> decline in motor activity
- ‘on-off’ phenomenon: large variations in motor performance, with normal function during the ‘on’ period, and weakness and restricted mobility during the ‘off’ period
- dyskinesias at peak dose: dystonia, chorea and athetosis
- these effects may worsen over time - clinicians therefore may limit doses until necessary
What drug may be used to manage dyskinesia associated with levodopa
amantadine
Which antiparkinson drug is associated with the highest chance of impulse control disorders
dopamine receptor agonists
Why is it important not to acutely stop levodopa, and what can be used if a Parkinson’s patient can’t take it orally?
- Stopping levodopa suddenly can cause withdrawal symptoms
- If a patient can’t take levodopa orally, a dopamine agonist patch can be used as rescue medication to prevent acute dystonia.
Give 4 examples of dopamine receptor agonists
- bromocriptine (ergot-derived)
- cabergoline (ergot-derived)
- ropinirole
- apomorphine
Give 2 adverse effects of dopamine receptor agonists
- pulmonary fibrosis (ergot-derived)
- impulse control disorders
Give an example of a MAO-B (Monoamine Oxidase-B) inhibitor
selegiline
Describe the mechanism of action of MAO-B
inhibits the breakdown of dopamine secreted by the dopaminergic neurons
Give an example of a COMT inhibitor
entacapone
How are COMT inhibitors used in the treatment of Parkinson’s
taken with levodopa (and a decarboxylase inhibitor) to slow down the breakdown of levodopa in the brain
Give 5 causes of parkinsonism
- drug-induced e.g. antipsychotics, metoclopramide (excluding domperidone)
- progressive supranuclear palsy
- multiple system atrophy
- Wilson’s disease
- post-encephalitis
Describe the features of multi system atrophy
- Parkinsonism
- autonomic dysfunction: postural hypotension, constipation, erectile dysfunction
- cerebellar dysfunction: ataxia
