Parkinson's Flashcards
definition of Parkinson’s
Neurodegenerative disease of the dopaminergic neurones of the substantia nigra,
associated with lewy bodies in the basal ganglia, brainstem and cortex
characterized by bradykinesia, rigidity, tremor and postural instability.
aetiology of Parkinson’s
sporadic and idiopathic - most common
- unknown
- env toxins and oxidative stress eg pesticides, wood pulp
secondary
- neuroleptic therapy eg schizophrenia
- vascular insults eg basal ganglia or midbrain strokes
- MPTP toxin from illicit drug contamination
- post-encephalitis eg influenza
- repeat head injury - boxing
familial forms
- gene mutations - in LRRK2, PARK2 (Parkin), PARK7, PINK1, SNCA (a-synuclein) genes
pathology of Parkinson’s
Degeneration of midbrain dopaminergic neurons projecting from the substantia nigra to the striatum (caudate nucleus and putamen)
Surviving neurons contain eosinophilic cytoplasmic inclusions (Lewy bodies)
Pts only symptomatic after >70% neuronal loss
Nigrostriatal dopaminergic deficiency causes abnormalities of plasticity in the basal ganglia and cerebral cortex
epidemiology of Parkinson’s
Very common 1-2% of >60yr olds.
Incidence is 20 in 100000.
Mean age onset 57yrs
prevalence increases with age - 3.5% at 85-89yrs
Sx of Parkinson’s
Insidious onset
parkisonian triad
Tremor at rest – noticed in hands
Stiffness and slowing of movements
Difficulty initiating movements – getting out of chair, rolling in bed
Frequent falls
Smaller hand writing – micrographia
Insomnia, mental slowness – bradyphenia
sleep disturbance
reduced sense of smell
signs of parkinsons
tremor
rigidity
gait
postural instability
Frontalis overactivation – furrowing of the brow
Expressionless face – hypomimia
Soft monotonous voice – hypophonia
Impaired olfaction on formal testing
Mild impairment of upgaze and tendency to drool – sialorrhoea
Involuntary movements in one part of the face associated with voluntary movement in another part of the face (synkinesis).
Psychiatric
autonomic dysfunction - postural hypotension, constipation, urinary frequency/urgency, dribbling of saliva
tremor in Parkinson’s
- Pill rolling rest tremor in hands – 4-6Hz
- Decreased on action or flexed tremor
- Asymmetrical
rigidity in Parkinsons
- Lead pipe rigidity of muscle tone, with superimposed tremor – cogwheel rigidity
- Can be enhanced by distraction – ask pt to keep raising and lowering other arm
Parkinsonion gait
- Stooped
- Simian
- Shuffling
- Small stepped
- Reduced arm swing
- Freezing – difficulty in initiating walking
postural instability in Parkinson’s
- Falls easily with little pressure from the back (propulsion) or front (retropulsion)
psychiatric sx in parkinsons
- Depression common
- Cognitive problems and dementia late in disease
- psychosis
common and dehabilitating
Ix for Parkinson’s disease
- Clinical diagnosis - based on core features of bradykinesia with resting tremor and/or hypertonia, cerebellar disease and fronto-temporal dementia. Signs invariably worse on 1 side.
- Levodopa trial
- Timed walking and clinical assessment after levodopa may be informative.
- Antiemetic (domperidone) may be needed.
- Blood
- Serum ceruloplasmin – excludes Wilson’s in young onset
- CT/MRI
- Exclude other causes of gait decline – hydrocephalus, vascular disease
- Dopamine transporter scintigraphy (DAT scan)
- Reduction in striatum and putamen
- Necessary for distinguishing from essential tumour
parkisonian triad
tremor - worse at rest, often pill-rolling of thumbs over fingers
hypertonia - rigidity and tremor = cogwheel rigidity, felt by the examiner in rapid pronation/supination
bradykinesia - slow to initiate movement, actions slow and decrease in amplitude with repitition eg reduced blink rate, micrographia. Gait is festinant (shuffling, pitched forward) with reduced arm swing and freezing obsticals or doors (due to poor simulataneous motor and cognitive function). Expressionless face
mx of parkinsons
mild
* carbidopa/levodopa
* exercise - functional and motor improvement
* PT OT SALT
if levodopa/carbidopa not working
* add COMT inhibitor, dopamine agonist, MAO-B inhibitor, istradefylline, or switch to extended-release carbidopa/levodopa
if dyskinesias
* reduce dopaminergic medications (if tolerated) or add amantadine
if nausea on carbidopa/levodopa or dopamine agonist
* additional carbidopa or antiemetic
for advanced parkinsonism - carbidopa/levodopa + physio
consider
* dopamine agonist
* MAO-B inhibitor
* COMT inhibitor
* istradefylline
with unpredictable off times - apomorphine
refractory tremor - deep brain stimulation
