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Corticobasal Degeneration (CBD)

Summary

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  • Rare neurodegenerative disorder characterised by asymmetric cortical and basal ganglia dysfunction
  • Presents with progressive asymmetric rigidity, apraxia, and cortical sensory loss
  • Imaging shows asymmetric cortical atrophy, particularly in frontoparietal regions1

Pathophysiology

  • Accumulation of hyperphosphorylated tau protein in neurons and glial cells
  • Affects cortical and subcortical regions, particularly motor cortex and basal ganglia
  • Progressive neuronal loss and gliosis in affected areas
  • Associated with mutations in the MAPT gene in some cases

Demographics

  • Typically affects individuals aged 60-80 years
  • Slight female predominance (1.5-2:1)
  • Estimated prevalence of 4.9-7.3 per 100,000 individuals

Diagnosis

  • Clinical diagnosis based on characteristic symptoms and signs:
    • Asymmetric limb rigidity and akinesia
    • Limb apraxia
    • Cortical sensory loss
    • Alien limb phenomenon
  • Supportive features:
    • Myoclonus
    • Dystonia
    • Cognitive impairment
  • Definitive diagnosis requires neuropathological confirmation

Imaging

  • MRI:
    • Asymmetric cortical atrophy, predominantly in frontoparietal regions
    • Atrophy of basal ganglia, particularly putamen
    • T2/FLAIR hyperintensity in subcortical white matter
  • FDG-PET:
    • Asymmetric hypometabolism in affected cortical regions and basal ganglia
  • DaTscan (123I-FP-CIT SPECT):
    • Asymmetric reduction in striatal dopamine transporter binding

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  • 70-year-old patient with apraxia, myoclonus and alien limb phenomenon.
  • MRI showed severe parietal atrophy but no parenchymal signal abnormality.

Treatment

  • No disease-modifying therapy; symptomatic management only (levodopa is usually poorly responsive)

Differential diagnosis (asymmetric perirolandic/frontoparietal atrophy)

Imaging differential Differentiating feature
Progressive supranuclear palsy Midbrain atrophy ("hummingbird"/"morning glory" signs); symmetric
Frontotemporal dementia Frontal/anterior temporal atrophy rather than perirolandic
Alzheimer's disease Temporoparietal and hippocampal atrophy; more symmetric
Posterior cortical atrophy Parieto-occipital atrophy

  1. Mahapatra et al. Corticobasal degeneration. 2004. The Lancet. Neurology - Open in new tab. ↩