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Multisystem Atrophy - Parkinsonian Type (MSA-P)

Summary

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  • MSA-P is a neurodegenerative disorder characterised by parkinsonian features, autonomic dysfunction, and cerebellar ataxia
  • Pathologically, it involves α-synuclein accumulation in oligodendrocytes and neuronal loss in multiple brain regions
  • Imaging reveals characteristic patterns of atrophy and signal changes in the basal ganglia, cerebellum, and brainstem1

Pathophysiology

  • Accumulation of α-synuclein in glial cytoplasmic inclusions (GCIs) in oligodendrocytes
  • Neuronal loss and gliosis in:
    • Substantia nigra
    • Striatum
    • Globus pallidus
    • Pontine nuclei
    • Inferior olivary nuclei
    • Cerebellar Purkinje cells
  • Degeneration of autonomic nuclei in the brainstem and spinal cord

Demographics

  • Typical onset: 50-60 years of age
  • Slight male predominance (1.3:1)
  • Estimated prevalence: 3-4 per 100,000 population
  • More common in Caucasian populations

Diagnosis

  • Clinical features:
    • Parkinsonism (bradykinesia, rigidity, postural instability)
    • Autonomic dysfunction (orthostatic hypotension, urinary incontinence, erectile dysfunction)
    • Poor response to levodopa therapy
  • Diagnostic criteria:
    • Probable MSA-P: Parkinsonism + autonomic failure/urinary dysfunction
    • Possible MSA-P: Parkinsonism + autonomic dysfunction or cerebellar syndrome

Imaging

  • MRI findings:
    • Putaminal atrophy with T2 hypointensity
    • "Hot cross bun" sign in pons (T2/FLAIR hyperintensity)
    • Cerebellar atrophy
    • "Putaminal rim" sign (T2 hyperintensity at lateral putaminal border)
  • DaTSCAN:
    • Reduced striatal dopamine transporter uptake
  • FDG-PET:
    • Hypometabolism in striatum, brainstem, and cerebellum

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  • 55-year-old female with left sided parkinsonism and orthostatic symptoms.

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  • 80-year-old patient presented with asymmetric parkinsonism (left > right) with freezing and early falls with poor response to levodopa.
  • MRI showed putaminal atrophy, susceptibility artefact and T2-hyperintensity along the lateral aspect of the putamina.
  • DaTscan showed markedly reduced tracer uptake in the putamina bilaterally.

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  • 60-year-old patient with a bilateral tremor.
  • T2 weighted imaging shows the lateral rim sign and mild putaminal volume loss.
  • While SWI was not performed, low signal was seen in the putamina on EPI DWI, which is sensitive to susceptibility artefact.

Treatment

  • Symptomatic only; parkinsonism responds poorly to levodopa

Differential diagnosis

Imaging differential Differentiating feature
Parkinson's disease Normal putamen and preserved nigrosome-1 sign is more typical; MSA-P shows putaminal atrophy, T2 hypointensity and a lateral rim
Progressive supranuclear palsy Midbrain atrophy ("hummingbird"/"morning glory"); superior cerebellar peduncle atrophy
Corticobasal degeneration Asymmetric perirolandic cortical atrophy
MSA-cerebellar type Predominant pontocerebellar atrophy with "hot cross bun" sign
Vascular parkinsonism Basal ganglia lacunes and confluent small vessel disease

  1. Krismer et al. Multiple system atrophy: advances in pathophysiology, diagnosis, and treatment. 2024. The Lancet. Neurology - Open in new tab. ↩