Parkinson's Disease Flashcards
What is Parkinson’s disease?
Neurodegenerative disease of the dopaminergic neurones of the substantia nigra, characterised by:
- Bradykinesia
- Rigidity
- Resting tremor
- Postural instability
Patients ~ demonstrate a combination of these motor symptoms + other non-motor symptoms.
What are the 2 classifications of Parkinson’s? (age-based)
-
Juvenile parkinsonism
- <21 years
-
Young-onset parkinsonism:
- 21 - 40 years.
What is the cause of Parkinson’s?
unknown, although several factors have been implicated:
-
genetic predisposition
- some rare autosomal dominant & recessive familial forms
-
subsequent environmental factors/exposures
- heavy metal exposure
- oxidative stress –> free radicals –> neuronal loss
- MPTP exposure –> specific damage to dopaminergic neurons in the nigrostriatal pathway
Which genes have been implicated in the pathophysiology of Parkinson’s?
- SNCA
- Parkin
- PINK-1
- DJ-1
- TREM2
- MHFTR
- LRRK2
- gene encoding glucocerebrosidase (GBA)
What are the proteins coded for by the implicated genes for Parkinson’s?
-
alpha-synuclein
- abnormal accumulation in the brain –> forms lewy bodies
-
glucocerebrosidase (GBA)
- x5 increased risk
- LRRK2 (leucine-rich repeat kinase 2)
- PINK-1 (a mitochondrial protein kinase)
- components of the ubiquitin-protease system
What are the risk factors for idiopathic Parkinson’s?
- old age
- mutation in gene encoding glucocerebrosidase
- MTP exposure
What are the risk factors for secondary Parkinson’s?
- Neuroleptic therapy (e.g. for schizophrenia)
- Vascular insults (e.g. in the basal ganglia)
- MPTP toxin from illicit drug contamination
- Post-encephalitis
- Repeated head injury
What are the risk factors for familial Parkinson’s?
- family Hx of Parkinson’s
Summarise the epidemiology of Parkinson’s
- Very COMMON
- Prevalence: 1-2% of > 60 yrs
What is the mean age of onset of Parkinson’s?
57 yrs
What are the presenting symptoms of Parkinson’s?
Motor
1) bradykinesia
- delay in initiating movements
- freezing of gait
2) resting tremor
3) rigidity
4) shuffling gait
- delay in initiating
- reduced arm swing
5) voice
- hypophonia
- hypokinetic dysarthria
6) hands
- micrographia
Neuropsychiatric
- depression
- Cognitive problems & dementia (in later stages)
- anxiety
Other
- insomnia
- fatigue
- constipation
What are the signs of Parkinson’s O/E
Motor
- rigidity - cogwheel
- bradykinesia
- resting tremor
- gait - GALS screen
- shuffling gait
- instability in mid-late disease
- eye gaze
- saccadic pursuit
- hypometric saccades
Neuropsychiatric
- Depression
- Cognitive problems and dementia (in later stages)
Other
- Frontalis overactivation (leads to furrowing of the brow) Hypomimic face
- Soft monotonous voice
- Impaired olfaction
- Tendency to drool
- Mild impairment of up-gaze
Describe the tremor in Parkinson’s
- Pill rolling rest tremor 4-6 Hz
- Decreased on action
- Usually asymmetrical
Describe the rigidity in Parkinson’s
- Lead pipe rigidity of muscle tone
- Superimposed tremor can cause cogwheel rigidity
- Rigidity can be enhanced by distraction
Describe the gait in Parkinson’s
- Stooped Shuffling
- Small-stepped gait
- Reduced arm swing
- Difficulty initiating walking
What are features of atypical Parkinson’s?
- acute onset
- rapidly progressive disease
signs/symptoms:
- cognitive impairment
- prominent postural instability
- severe autonomic dysfunction
- significant neuropsychiatric features i.e.
- hallucinations
- fluctuating levels of arousal
What is the diagnostic investigation for Parkinson’s?
clinical diagnosis
- Hx
- Examination
What test can be used to confirm a diagnosis of Parkinson’s?
dopaminergic agent trial
- if there are atypical features present - useful to confirm diagnosis
- –> should see improvement in symptoms
What further investigations can be considered for pts with Parkinson’s?
-
MRI brain
- only if atypical Parkinson’s is suspected
-
functional neuroimaging
- only if atypical Parkinson’s is suspected
- allows to distinguish between neurodegenerative parkinsonian disorder and vascular, drug-induced, or psychogenic parkinsonism
- positive = decreased basal ganglia (putaminal) pre-synaptic dopamine uptake
- genetic testing
-
neuropsychometric testing
- positive = executive dysfunction
What investigations of exclusion can be conducted in ?Parkinson’s
ONLY IN YOUNGER PTS
serum ceruloplasmin
- to exclude Wilson’s disease
- positive result for Wilson’s = low
24-hour urine copper
- elevated in Wilson’s disease
What would be seen on brain MRI in pts with Parkinson’s?
absent swallow-tail-sign
- i.e. absence of dorsolateral nigral hyperintensity
- (see image - bottom is absence of swallow tail sign)*
What would be seen on post-mortem in pts with Parkinson’s?
Gross:
- frontal atrophy
- loss of pigmented cells of substantia nigra
Microscopic:
- nigrostriatal degeneration
- Lewy bodies
- immunohistochemical staining –> positive reactivity to synuclein
