Parkinson’s Disease Flashcards
What is Parkinson’s Disease?
Parkinson’s disease is a condition where there is a progressive reduction of dopamine in the basal ganglia of the brain, leading to disorders of movement. The symptoms are characteristically asymmetrical, with one side affected more than the other.
What is the classical triad of PD?
Resting tremor
Rigidity
Bradykinesia
What are basal ganglia?
The basal ganglia are a group of structures situated in the middle of the brain. They is responsible for coordinating habitual movements such as walking or looking around, controlling voluntary movements and learning specific movement patterns
What is the substantia nigra?
Part of the basal ganglia called the substantia nigra produces a neurotransmitter called dopamine. Dopamine is essential for the correct functioning of the basal ganglia.
What is the pathophysiology of PD?
gradual but progressive fall in the production of dopamine.
Main presentation of PD
Common
- pill rolling tremor (pronounced on rest)
- cogwheel rigidity
- bradykinesia
- shuffling gait
- hypomimia
- asymmetrical
Other
- depression
- sleep disturbance
- anosomia
- postural instability
- cognitive impairment
Differentiating PD and BET
PD:
- asymmetrical, 4-6Hz, worse at rest and improves with intentional movement, no change with alcohol
BET:
- symmetrical, 5-8Hz, improves at rest and worse with intentional movement, improves with alcohol.
What are a few parkinsons plus syndromes
- Multiple system atrophy
- Demential with lewy bodies
- Progressive supranuclear palsy
- Corticobasal degeneration
What os multiple system atrophy?
Rare condition where the neurones of multiple systems in the brain degenerate.
It affects the basal ganglia as well as multiple other areas. The degeneration of the basal ganglia lead to a Parkinson’s presentation.
The degeneration in other areas lead to autonomic dysfunction (causing postural hypotension, constipation, abnormal sweating and sexual dysfunction) and cerebellar dysfunction (causing ataxia).
What is dementia with lewy bodies?
This is a type of dementia associated with features of Parkinsonism. It causes a progressive cognitive decline. There are associated symptoms of:
- visual hallucinations
- delusions
- disorders of REM sleep
- fluctuating consciousness.
How do you diagnose PD?
- clinical diagnosis
- diagnosis made by specialist
- NICE recommend using the UK Parkinson’s Disease Society Brain Bank Clinical Diagnositc Criteria
Management options for PD
- Levodopa
- COMT inhibitors
- Dopamine agonists
- Monoamine oxidase-B inhibitors
What is levodopa?
synthetic dopamine given orally to boost their own dopamine levels.
What are peripheral decarboxylase inhibitors
drug that stops levodopa being broken down in the body before it gets the chance to enter the brain.
Commonly combined with levodopa
E.g Co-benyldopa (levodopa and benserazide)
Co-careldopa (levodopa and carbidopa)
Efficay of levodopa
Levodopa is the most effective treatment for symptoms but becomes less effective over time. It is often reserved for when other treatments are not managing to control symptoms.
Side effects of levodopa
dyskinesias
These are abnormal movements associated with excessive motor activity.
Examples are:
- Dystonia: This is where excessive muscle contraction leads to abnormal postures or exaggerated movements.
- Chorea: These are abnormal involuntary movements that can be jerking and random.
- Athetosis: These are involuntary twisting or writhing movements usually in the fingers, hands or feet.
Example of COMT inhibitors
Entacapone
How does COMT inhibitors work?
These are inhibitors of catechol-o-methyltransferase (COMT). The COMT enzyme metabolises levodopa in both the body and brain. Entacapone is taken with levodopa (and a decarboxylase inhibitor) to slow breakdown of the levodopa in the brain. It extends the effective duration of the levodopa.
How do dopamine agonists work?
mimic dopamine in the basal ganglia and stimulate the dopamine receptors.
Efficacy of dopamine agonists
less effective than levodopa in reducing symptoms.
They are usually used to delay the use of levodopa and are then used in combination with levodopa to reduce the dose of levodopa that is required to control symptoms.
Side effect of dopamine agonsits
Prolonged use can cause pulomary fibrosis
Examples of dopamine agonists
Bromocryptine
Pergolide
Carbergoline
What are monoamine oxidase-B inhibitors
Monoamine oxidase enzymes break down neurotransmitters such as dopamine, serotonin and adrenaline.
The monoamine oxidase-B enzyme is more specific to dopamine and does not act on serotonin or adrenalin.
These medications block this enzyme and therefore help increase the circulating dopamine.
What are examples of MOABI
Selegiline
Rasagiline
