7 - Parkinson's Disease Flashcards
is tremor always present in PD?
no - absent in 30%
what genetic factors can result in PD?
- recessive genes - parkin
- dominant genes - SNCA
- dysfunction in cellular pathways
what are environmental factors that can result in PD?
- toxins - paraquat (herbicide commonly used in rural USA)
- ? spread of toxic/infective agents from gut/olfactory systems
what are the diagnostic criteria for PD?
- bradykinesia + tremor and/or rigidity
- absence of red flags
at least one of: - clear response to dopaminergic therapy
- levodopa-induced dyskinesia
- rest tremor
- olfactory loss
list 4 red flags for PD diagnosis
- symmetrical onset
- early gait abnormality and falls
- pyramidal tract signs
- poor levodopa response
- supranuclear gaze palsy
- early dementia
early gait abnormality, supranuclear gaze palsy, and early dementia would be red flags for PD - what may they be indicative of instead?
PSP - progressive supranuclear palsy
dysautonomia (disorder of involuntary functions), ataxia (disorders of coordination, balance and speech) and stridor (inspiration + expiration) are red flags for PD - what are they indicative of instead?
MSA - multiple system atrophy
apraxia (loss of ability to carry out skilled movement), myoclonus (twitching of muscles), alien limb (hand acts independently) are red flags for PD - what may they be indicative of instead?
CBS - corticobasal syndrome
what are possible pre-motor symptoms in PD?
- REM sleep behaviour disorder - act out dreams during night
- anosmia - loss of sense of smell
- constipation
- depression
- pain
what is the typical age of onset of PD?
- > 60
- young onset - (<40) in 5%
what is the mechanism of bradykinesia?
- increased inhibitory output to brainstem
- increased inhibitory output to thalamus and motor cortex
bradykinesia is associated with abnormal oscillations in basal ganglia circuits - what abnormal frequency is this?
20Hz
when is rigidity most obvious?
during slow movements
when is spasticity most obvious?
during velocity-dependent movements
what is the pathophysiology of rigidity in the periphery?
- reduced inhibition from type Ib fibres
- overactive type II fibres
- increased activity due to peripheral stimulation
what is the pathophysiolofy of rigidity in the central system?
- altered GABA and ACh activity in interneurons
- altered inhibition in indirect pathway
tremor is absent in roughly what % of PD pts?
30
is tremor more or less responsive to dopaminergic drugs?
less
where is tremor initiated? what brain region amplifies tremor activity?
initiated - basal ganglia
amplified - cerebellar-thalamo-cortical loops
what drugs are commonly used to treat tremor?
rasagiline
why isn’t dopamine given directly to treat PD?
it doesn’t pass the BBB - hence why it’s given as L-dopa
why are dopamine agonists less preferred than levodopa?
- more adverse effects
- impulse control disorders
- withdrawal problems
what are two motor complications in PD?
- wearing-off and motor functions
- L-dopa-induced dyskinesia
