Parkinson's disease/parkinsonism Flashcards
How common is it?
Prevalence: 120-230 per 100,000 (0.12-0.23%)
Who does it affect?
1% of people older than 65 are diagnosed with it. 4-8% of people with Parkinson’s are below 50. 1.5X more common in men.
What causes it?
Parkinsonism is an umbrella term for the clinical syndrome involving bradykinesia together with at least one of the following: rigidity, tremor and postural instability.
Parkinson’s disease is the most common form of parkinsonism (so I shall focus on that in this core condition.) Other causes of parkinsonism include drug-induced, CVD, Lewy body dementia, multiple system atrophy, and progressive supranuclear palsy.
In Parkinson’s disease, there is progressive depletion of dopamine -secreting cells in the substantia nigra, but the actual cause is unknown.
What risk factors are there?
There is a clustering of early onset PD in some families. Linked to mutations in α synuclein
How does it present?
Features tend to present unilaterally initially, but become bilateral as the disease progresses (slow progression).
Bradykinesia: slow initiation of voluntary movement with progressive reduction in speed and amplitude of repetitive actions, such as finger and foot tapping.
Hypokinesia (poverty of movement) for example: Reduced facial expression, arm swing or blinking. Difficulty with fine movements such as buttoning clothes and opening jars, or small cramped handwriting (micrographia). Slow, shuffling, festinating gate, or difficulty turning in bed.
Stiffness or rigidity which may be lead pipe or cogwheel.
Resting tremor: usually improves on moving, with mental concentration, and during sleep. Is absent in 30% of people at onset.
Postural instability. May also get the following in early disease and may even precede motor symptoms:
Depression, anxiety, fatigue, reduced sense of smell, cognitive impairment, sleep disturbance, constipation.
Investigations
The diagnosis is clinical
Treatment
Levodopa (L-dopa, a dopamine precursor) with a peripheral decarboxylase inhibitor – benserazide or carbidopa. This combination therapy reduces the peripheral side-effects, principally nausea, of L-dopa and its metabolites. Over the years this therapy becomes less effective, even when increasing the doses. May switch between periods of dopamine induced dyskinesia’s (choreas and dystonic movement) and periods of immobility (on-off syndrome).
Dopamine agonists are non-ergot dopamine agonists (ropinirole, pramipexole, rotigotine). Possible side effects are impulse control disorders (pathological gambling, compulsive shopping, hypersexuality) and excessive sleepiness.
Monoaimine oxidase B inhibitor: (e.g. selegiline) inhibits the catabolism of dopamine in the brain.
Physiotherapy can improve gait and help to prevent falls.
Conditions that would present similarly
Drug induced parkinsonism (Antipsychotics, anti-emetics and others).
Strokes/TIAs
non-Parkinson dementia (Lewy body, Alzheimer’s).
Degenerative parkinsonian (Parkinson plus).
Wilsons disease.
Tremors can be caused by essential tremor, exaggerated physiological tremor, hyperthyroidism, β 2 agonists, cerebellar lesions.
