Parkinson’s disease
Definition of Parkinson’s Disease
Neurodegenerative disease of the dopaminergic neurones in the substantia nigra,
characterized by bradykinesia, rigidity, tremor and postural instability.
Parkinsonism:
Neurological syndrome characterised by tremor, bradykinesia and rigidity.
Aetiology of Parkinson’s
Idiopathic – cause unknown. Some familial forms have been found with genetic mutations in
Parkin and alpha-synuclein genes.
Causes of parkinsonism:
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Drugs
- Antipsychotics (for example haloperidol, olanzapine)
- Anti-nausea agents (for example prochlorperazine, metoclopramide)
- Antihistamines (for example cinnarizine).
- Tricyclic antidepressants
- MPTP
Vascular disease (basal ganglia or midbrain strokes)
Parkinson plus syndromes (multiple system atrophy, progressive supranuclear palsy,
corticobasal degeneration, dementia with Lewy bodies)
Trauma (boxing)
Wilson’s disease
Creutzfeldt-Jacob Disease
Post encephalitis (e.g. influenza)
AIDS
Parkinson plus syndromes:
These are groups of neurodegenerative conditions that have features of Parkinson’s disease
but also other added features that differentiate them from Idiopathic Parkinson’s disease:
Diffuse Lewy Body Disease (unknown cause, but some genetic links have been found):
Dementia, cognitive fluctuations and visual hallucinations.
Multiple system atrophy (Shy-Drager syndrome, unknown cause): Autonomic failure,
cerebellar and extrapyramydal features.
Progressive supranuclear palsy (genetic inherited factors, but also possibly caused by
environmental toxins): Impairment of voluntary vertical saccades (upgaze first, then
downgaze), and dementia
Cortico-basal degeneration (unknown underlying cause but due to damage to basal ganglia):
Dystonia, dyspraxia, “alien hand syndrome”, dementia
Epidemiology of Parkinson’s disease
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Overall prevalence ≈ 160 / 100 000
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Incidence rates ≈ 20 / 100 000 / year
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2% of people over 80 are affected
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Mean age at onset 60
Presentation – symptoms and signs
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Classic triad – Bradykinesia, pill rolling tremor, rigidity
But UK Brain Bank Criteria is bradykinesia AND at least one of rigidity, 4-6Hz tremor,
or postural instability
Ask about:
Onset - gradual
Tremor – at rest, usually first noticed in the hands
Stiffness and slowness of movement.
Difficulty initiating movements (e.g. getting out of chair, rolling in bed)
Falls – Not usually frequent early on
Smaller hand writing (micrographia)
Important: Remember that often patients will be more concerned about the non motor
symptoms than the motor symptoms. The non-motor symptoms can be grouped into
psychiatric and non-psychiatric. Most common are anxiety and depression, which many
Parkinson's disease patients will have. There are also a long list of non-psychiatric
symptoms such as insomnia,constipation, weight loss, urinary incontinence, and sexual
dysfunction.
Examination
Remember there are a huge number of things you can comment on by just observing
someone with Parkinson’s disease:
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Tremor, decreased by action and usually asymmetrical
Expressionless face (hypomimia), Frontalis overactivation (furrowing of the
brow), soft monotonous voice (hypophonia).
Gunslinger posture/Hands over hernias
You should also get the patient to walk to assess their gait, check for rigidity, bradykinesia,
and assess function:
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Gait – Stooped posture, shuffling, small steps, reduced arm swing. Freezing
(difficulty initiating walking)
Rigidity – Leadpipe rigidity of muscle tone, with superimposed tremor (giving
rise to cogwheel rigidity) Rigidity can be increased by distraction, e.g. by
asking the patient to clap one hand on their thigh while you check tone in the
other hand.
Bradykinesia – thumb-finger test (Crab-claw test). Ask the patient to quickly
open and close their hand with finger opposed to thumb. Parkinson’s patients
are very slow to do this usually.
Function – ask them to write, or do up some buttons.
In the exam you could state after your initial examination that you would do a MMSE if you
had more time to check for dementia
Investigations
Parkinson’s disease is a clinical diagnosis but investigations can be of help in excluding
other causes of parkinsonism:
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Bedside tests
o Levodopa trial – timed walking and clinical assessment after levodopa.
Blood tests
o Routine bloods
o Serum ceruloplasmin for Wilson’s disease
Imaging
o CT and MRI usually normal but may exclude other causes of parkinsonism or
gait decline (vascular disease, hydrocephalus)
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Special tests – Dopamine transporter scintigraphy (DAT): Reduction in striatum and
putamen. May be necessary to distinguish Parkinson’s from essential tremor.
Management
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Conservative
o Support societies
o Physio
o OT
Medical
o Dopamine agonists e.g. ropinirole, bromocriptine
o MAO inhibitors e.g. selegeline
o Levodopa + decarboxylase inhibitor
o COMT e.g. Entacapone
o Continuous dopamine therapy – Apomorphine (syringe driver) or Duodopa
(Intrajejunal infusion of levodopa gel)
o Supportive medication e.g. baclofen
Dopamine agonist
Significant functional disability
Disease progression
MAO-B inhibitor
Levodopa (max 600mg/day)
Add levodopa (max 600mg/day)
Motor complications develop
Guidelines for drug
management of PD
Add DA or entacapone
Add entacapone or DA
Switch to tolcapone if entacapone fails
Add MAO-B inhibitor if not already given
Add amantadine for dyskinesia
Severe motor complications
Consider apomorphine, Duodopa, DBS
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Surgery
Stereotactic thalamic surgery - Bilateral subthalamic nucleus stimulation (deep brain
stimulation)
May reduce levodopa requirements and therefore reduce levodopa induced
dyskinesias
Complications of treatment (develops over months and years on chronic levodopa therapy):
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On-off motor fluctuations
Peak dose dyskinesias (typically choreiform/dancelike)
On-off dystonia
Impulse control disorders (e.g. pathological gambling, hypersexuality)
Prognosis
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Progression variable
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Usually the course is over 10-15 years
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Death from bronchopneumonia
References/Sources:
- Sam AH, Teo JTH, Rapid Medicine, Wiley-Blackwell 2010
- BMJ learning module: Parkinson's disease - initial assessment and referral
- Lecture by Zoe Campell, Warwick Hospital, 2012
- SADH lecture by Naghme Adab, Management and treatment of Parkinson’s Disease, 2012