Parkinsonism and Parkinson-Plus Syndromes
Scope of this article:
This article covers parkinsonism as an umbrella clinical syndrome, including its main causes and the key Parkinson-plus / atypical parkinsonian syndromes.
For idiopathic Parkinson’s disease, see Parkinson’s Disease (PD)
Terms and Definitions
Four commonly confused terms that are related but not interchangeable:
| Term | Definition |
|---|---|
| Parkinsonism (Parkinsonian syndrome) | An umbrella term, a clinical syndrome defined by the presence of bradykinesia plus at least one of the following: tremor, rigidity, postural instability |
| Parkinson’s disease | Idiopathic (primary) form of parkinsonism. Parkinson’s disease is the most common form of parkinsonism
Caused by dopaminergic neuron degeneration in the substantia nigra due to Lewy body deposition |
| Parkinson-plus syndromes (atypical parkinsonism) | A group of primary neurodegenerative disorders that mimic Parkinson’s disease with additional “plus” features and are often poorly responsive to levodopa
Key examples include Lewy body dementia, multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration |
| Secondary parkinsonism | Parkinsonism caused by an identifiable cause (i.e. non-idiopathic), such as drugs or toxins |
Parkinsonism Causes
There are 3 categories of Parkinsonism causes: [Ref1][Ref2]
| Category | Description / causes |
|---|---|
| Parkinson’s disease | Parkinson’s disease refers to the primary idiopathic form and the most common cause of Parkinsonism |
| Parkinson-plus syndromes (atypical parkinsonism) | A group of primary neurodegenerative disorders, key ones include:
|
| Secondary parkinsonism | Drug-induced (non-exhaustive):
Toxin-induced:
Neurological conditions
|
Features of Parkinsonism
Parkinsonism is defined by the presence of bradykinesia plus at least one of the following: tremor, rigidity, postural instability
| Category | Description / symptoms |
|---|---|
| Bradykinesia | Bradykinesia: slowness in initiating and performing voluntary movement + progressive reduction in speed and amplitude of sustained repetitive actions
May present as:
Bradykinesia can be assessed clinically by asking the patient to perform repetitive movements like finger tapping, hand opening and closing, and foot tapping Look for slowness, reduced amplitude, and progressive decrement. |
| Rigidity | Asymmetrical, predominantly affecting the side of onset
|
| Tremor |
A tremor can be absent in up to 20% of patients with PD |
| Postural instability | Postural instability is suggested by the ‘pull test’ – a tendency to fall backwards after a sharp forward pull from the examiner |
Drug-induced parkinsonism typically presents as: [Ref]
- Symmetrical parkinsonism
- Prominent bradykinesia and rigidity
- Symptoms typically resolve within weeks to months after withdrawing the causative agent
Note that it can also closely mimic Parkinson’s disease.
Parkinson-Plus Syndromes (Atypical Parkinsonism)
Parkinson-plus syndromes are characterised by:
- Parkinsonism, and
- Additional ‘plus’ features (e.g. faster progression, symmetrical onset), and
- Poor response to levodopa
Dementia with Lewy Bodies
Core tetrad features:
- Parkinsonism
- Fluctuating cognition
- Visual hallucinations (tend to involve humans or animals)
- REM sleep disorder
Autonomic failure (e.g. orthostatic hypotension) is also common. Memory impairment may not be apparent in early stages
For management, see the Dementias article
Dementia with Lewy bodies vs Parkinson’s disease dementia
They are closely related conditions within the spectrum of Lewy body disease, a textbook rule:
- Dementia with Lewy bodies: dementia develops before or within 1 year of parkinsonism
- Parkinson’s disease dementia: dementia develops after 1 year of parkinsonism
Multiple System Atrophy (MSA)
Typical presentation: [Ref]
- Parkinsonism
- Tends to be rapidly progressive
- Bradykinesia and rigidity are usually predominant (a classic pill-rolling tremor is rarely seen)
- Autonomic failure – a core feature
- Orthostatic hypotension, syncope
- Urinary incontinence
- Erectile dysfunction
- Cerebellar ataxia
MSA is classified into 2 subtypes based on the predominant presenting features: MSA-C (cerebellar features) or MSA-P (parkinsonian features) [Ref]
MRI brain can be used to differentiate MSA from Parkinson’s disease: [Ref]
- Changes seen in the brainstem and basal ganglia
- Classic “hot cross bun” sign – bright, cross-shaped pattern (cruciform hyperintensity) in the middle of the pons on transverse view
Exam tip:
Parkinsonism + autonomic failure = multiple system atrophy
Progressive Supranuclear Palsy (PSP)
Typical presentation: [Ref]
- Parkinsonism
- Symmetrical parkinsonism
- Tends to cause axial rigidity → upright +/- retrocollis posture (as opposed to the stooped posture in Parkinson’s disease)
- Abnormal eye movement
- Classically impaired vertical eye movement
- Recurrent falls (classically backwards)
- Behavioural and cognitive features
- Executive function
- Verbal fluency
- Apathy (seen in 80% of patients)
- Impulsivity
MRI brain can be used to differentiate PSP from Parkinson’s disease: [Ref]
- Midbrain atrophy
- Classic “hummingbird sign” – atrophied midbrain resembles the head and beak of a hummingbird on sagittal view
Exam tip:
Parkinsonism + falls + eye movement problems = progressive supranuclear palsy
Corticobasal Degeneration (CBD)
Typical presentation: [Ref]
- Parkinsonism
- Markedly asymmetrical limb rigidity or akinesia
- +/- Dystonia and myoclonus
- Typical resting tremor is often absent
- Higher cortical features (key in distinguishing CBD from Parkinson’s disease)
- Alien limb phenomenon – the patient feels that the limb does NOT belong to them / the limb has a will of its own / the limb independently performs complex unintentional tasks
- Sensory loss
- Apraxia
- Progressive non-fluent aphasia
- Cognitive impairment and behavioural changes
MRI brain is helpful, but NOT diagnostic; diagnosis of CBD is primarily clinical: [Ref]
- Typical finding: asymmetric atrophy primarily involving the frontal and parietal cortices