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Multiple System Atrophy

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Overview

Multiple system atrophy (MSA) is a rare neurodegenerative disorder that is characterised by Parkinsonism and autonomic dysfunction. It is a type of Parkinson-plus syndrome and occurs due to degeneration of the basal ganglia, inferior olivary nucleus, and cerebellum.

The mean time from disease onset to death is around 10 years.

Classification

MSA can be divided into:

  • MSA with predominant Parkinsonism (MSA-P)
  • MSA with predominant cerebella ataxia (MSA-C)

Epidemiology

  • MSA is rare with a worldwide incidence of 3 in 100,000 per year in those >50 years
  • The average age of onset is a person’s 50s

Presentation

  • Parkinsonism – remembered with TRAP:
    • Tremors
    • Rigidity
    • Akinesia/bradykinesia
    • Postural instability
  • Autonomic dysfunction:
  • Cerebellar signs:
    • Poor coordination
    • Ataxic gait
    • Nystagmus
  • Cognition is preserved

Differential Diagnoses

Idiopathic Parkinson’s disease

  • Features of Parkinson’s disease are present without autonomic or cerebellar dysfunction
  • Parkinson’s disease tends to be more responsive to levodopa than MSA

Drug-induced Parkinsonism

  • Features of Parkinson’s disease are more commonly bilateral
  • Features should stop upon ceasing the offending drug

Progressive supranuclear palsy

  • Autonomic dysfunction is not as prominent
  • Postural instability is more of a prominent feature
  • Impaired vertical gaze (downwards gaze is worse than upwards gaze)
  • Cognitive impairment is present – in MSA, cognition is relatively preserved
  • Poor response to levodopa

Normal pressure hydrocephalus

  • Usually an elderly patient presenting with a triad of confusion, ataxia, and urinary incontinence
  • Features of Parkinsonism and autonomic dysfunction are not present

Investigations

MSA is diagnosed clinically by a specialist in movement disorders. Some investigations similar to Parkinson’s disease are performed to rule out other underlying causes:

  • FBC, U&Es, LFTs, CRP:
    • To screen for metabolic or infectious causes
  • HIV and syphilis serology:
    • To screen for HIV or neurosyphilis
  • Copper studies:
  • Neuroimaging:
    • MRI brain – may show atrophy of the pons and middle cerebellar peduncle
    • Positron emission tomography (PET) scan with 18F-fluorodeoxyglucose – may show reduced metabolism
  • Levodopa trial:
    • Parkinson’s disease may respond well to levodopa, however, MSA may not

Management

Overview

There is no cure and treatment is mainly aimed at symptoms:

  • Parkinsonism: levodopa and physiotherapy
  • Orthostatic hypotension: midodrine (alpha agonist)
  • Urinary incontinence: desmopressin (anti-diuretic hormone analogue)
  • Urinary retention: urinary catheterisation
  • Psychological therapy

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