Parkinson's Disease Flashcards
what are the 3 characteristic features of Parkinsonism?
akinesia (can be bradykinesia or hypokinesia)
tremor (4-6 Hz resting tremor described as a pill rolling tremor)
rigidity (lead-pipe or cogwheel)
how can akinesia be tested for?
ask patient to repeatedly oppose middle finger and thumb
will cause fatiguing and decrementing amplitude of the repeated movement
how can a resting tremor be tested for?
ask the patient to count backwards from 100
resting tremor will become more apparent as it is induced by concentration
how is rigidity be tested for?
flex and extend the patient’s relaxed wrist and elbow joint
what is parkinson’s disease?
progressive neurodegenerative movement disorder characterized by levodopa responsive parkinsonism
histology of parkinson’s disease?
neuronal loss
presence of intracytoplasmic, eosinophilic alpha synuclein containing inclusions called Lewy Bodies
what do lewy bodies do?
target the pars compacta of the substantia nigra causing disturbance in the dopaminergic pathway
how is parkinson’s disease diagnosed?
clinically
characteristic features
starts asymmetrically
older patients
clinical features of parkinson’s disease?
parkinson's triad = cardinal features flexed posture and postural instability (later features) shuffling gait micrographia (small handwriting) masked facies (loss of facial expressions) non-motor symptoms - constipation - REM sleep disorder - depression - dementia
most effective medication for parkinsons?
levodopa
mode of action of levodopa?
dopamine precursor that can cross the blood-brain barrier
side effects of levodopa?
hypotension
nausea
dyskinesia
over time patients may start to notice levodopa becoming less effective
what is given alongside levodopa to prevent peripheral metabolism of levodopa?
peripheral dopa-decarboxylase inhibitors (carbidopa)
how do monoamine oxidase B inhibitors (rasagiline and selegiline)?
inhibits monoamine oxidase B which is responsible for catabolising dopamine to homovanillic acid
side effects of monoamine oxidase inhibitors?
hypertensive crisis when consuming tyramine containing foods (such as cheese, red wine etc)
how are monoamine oxidase inhibitors used?
can be used as add on or even as monotherapy in early mild parkinsons
how do dopamine agonists work (e.g pramipexole)?
stimulate dopamine receptors directly
side effects of dopamine agonists?
hypotension
nausea
ankle swelling
hallucinations
how are dopamine agonists used in parkinsons?
can be used as an initial treatment in younger patients (<70) due to the high risk of dyskinesia in younger patients using levodopa
features of drug induced parkinsonism?
onset of parkinsonian features
often symmetrical developing a few weeks after starting or raising dose of some medication or after withdrawing from anti-parkinsonian agent
examples of drugs associated with drug induced parkinsonism?
chlorpromazine haloperidol lithium valproic acid metoclopramide
how is drug induced parkinsonism managed?
cessation of the causitive drug
- cant just stop typical antipsychotic so should be switched to an atypical due to lower risk of extra pyramidal side effects
anticholinergics such as benztropine and procyclidine can be used for symptomatic relief
how can lewy body dementia and parksinson’s dementia be differentiated?
dementia >1 year after onset of parkinsons = parkinsons dementia
dementia before or at same time as parkinsons onset = lewy body
3 core features of lewy body dementia?
progressive disabling cognitive impairment (dementia)
recurrent visual hallucinations
features of parkinsonism
