Parkinson-Plus Syndromes
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Direct answer
Parkinson-plus syndromes are atypical parkinsonian disorders in which parkinsonism occurs with extra features and a poor response to levodopa. The three main types are multiple system atrophy, progressive supranuclear palsy and corticobasal degeneration. Vertical gaze palsy, early falls and autonomic failure point towards this group rather than idiopathic Parkinson disease.
What you must remember
- Levodopa response: weak or short-lived across all Parkinson-plus syndromes, which is the main clinical discriminator from idiopathic Parkinson disease.
- Multiple system atrophy: autonomic failure with orthostatic hypotension, early urinary incontinence or erectile dysfunction, and cerebellar (MSA-C) or parkinsonian (MSA-P) features, with REM sleep behaviour disorder often preceding it.
- MSA clues: inspiratory stridor from vocal cord abductor palsy; on MRI, a cruciform pontine hyperintensity, the hot cross bun sign, in MSA-C and a putaminal rim in MSA-P.
- Progressive supranuclear palsy: vertical supranuclear gaze palsy, typically downgaze first, with early backward falls, axial rigidity, pseudobulbar palsy and frontal cognitive change.
- PSP imaging: midbrain atrophy on sagittal MRI, the hummingbird sign, which supports the diagnosis alongside the clinical picture.
- Corticobasal degeneration: asymmetric rigidity and bradykinesia, limb apraxia, cortical sensory loss, myoclonus and the alien limb phenomenon.
- Management: levodopa may be trialled but responses are poor; care is symptomatic, with physiotherapy, fall prevention and treatment of orthostatic hypotension using fludrocortisone or midodrine.
Comparing the three syndromes
A stem describing a 62-year-old with early falls, a stiff gait and poor response to levodopa usually asks you to name the group first and then the subtype. The table separates them by the clue that dominates each disorder.
| Feature | MSA | PSP | CBD |
|---|---|---|---|
| Dominant pattern | Autonomic failure with parkinsonism or ataxia | Vertical gaze palsy and postural instability | Asymmetric limb rigidity with apraxia |
| Early falls | Common | Very early, backwards | Variable |
| Autonomic symptoms | Prominent | Usually absent | Usually absent |
| Eye signs | Gaze-evoked nystagmus in MSA-C | Vertical supranuclear gaze palsy | Not a defining feature |
| Imaging clue | Hot cross bun sign or putaminal rim | Hummingbird sign | Asymmetric cortical atrophy |
MSA is the one to think of when autonomic symptoms come early, PSP when vertical eye movements are impaired, and CBD when a limb behaves as if it has a will of its own. Overlap is common in the early years, so the exam usually expects you to pick the dominant feature in the stem rather than a single finding.
Where the exam tries to catch you
The stem usually supplies one clue that separates a Parkinson-plus syndrome from idiopathic disease.
- Trap: choosing levodopa as the best answer for a parkinsonian patient with early falls Correct: early falls and poor levodopa response point to a Parkinson-plus syndrome rather than idiopathic disease.
- Trap: attributing vertical gaze palsy to idiopathic Parkinson disease Correct: a vertical supranuclear gaze palsy, especially of downgaze, is a feature of PSP.
- Trap: labelling parkinsonism with orthostatic hypotension as idiopathic Correct: early autonomic failure raises the likelihood of MSA strongly.
- Trap: calling parkinsonism with fluctuating cognition and visual hallucinations MSA Correct: that combination points to dementia with Lewy bodies, a separate entity.
Frequently asked questions
Which feature most strongly separates MSA from idiopathic Parkinson disease?
Early autonomic failure, such as orthostatic hypotension, urinary incontinence or erectile dysfunction, is the most specific clue for multiple system atrophy. Levodopa response is also usually poor in MSA, unlike the sustained benefit seen in idiopathic Parkinson disease.
Why does progressive supranuclear palsy cause early falls?
Progressive supranuclear palsy causes early, backward falls because of axial rigidity, impaired postural reflexes and supranuclear gaze impairment. Falls usually appear within the first years of illness, which is an important distinction from idiopathic Parkinson disease.
What MRI sign supports progressive supranuclear palsy?
The hummingbird sign on sagittal MRI reflects midbrain atrophy and supports the diagnosis of progressive supranuclear palsy. It is supportive rather than diagnostic on its own, so it is always read alongside the clinical features.
Is levodopa useful in corticobasal degeneration?
Levodopa response in corticobasal degeneration is usually poor, although a short trial may be given. Asymmetric rigidity, limb apraxia and the alien limb phenomenon point to corticobasal degeneration rather than idiopathic Parkinson disease.
Which drugs treat orthostatic hypotension in multiple system atrophy?
Fludrocortisone and midodrine are used to raise blood pressure in multiple system atrophy with symptomatic orthostatic hypotension. Non-drug measures such as raising the head of the bed and adequate fluid intake are also part of the management.