Corticobasal syndrome


Corticobasal syndrome is a clinical diagnosis which is caused by heterogeneous pathological processes. Corticobasal degeneration refers to the post-mortem finding of selective atrophy of cortical regions and the basal ganglia. There is a poor correlation between corticobasal syndrome – i.e. the clinical diagnosis – and corticobasal degeneration.

Core pathological features include diffuse brain atrophy and the presence of abnormal aggregations of phosphorylated protein tau, e.g. inclusions inside astrocytes, and neurofibrillary tangles.


CBS classically presents as a progressive, asymmetrical parkinsonian disorder with progressive cognitive deficits and other cortical signs, including pyramidal movement disorders and cortical sensory loss.

Motor features:

  • Falls
  • Abnormal gait
  • Rigidity
  • Bradykinesia
  • Myoclonus
  • Tremor
  • Dystonia

Eye movement abnormalities:

  • Slowing of saccades
  • Loss of smooth saccades

Cogntive deficits

  • Apraxia
  • Dementia
  • Aphasia
  • Behavioural disturbance

Sensory deficits

  • Alien limb
  • Astereognosis


The diagnosis of CBS should be suspected in patients presenting with an atypical parkinsonian disorder.

Important investigations:

  • Bloods
    • Reversible causes of cognitive impairment
    • Consider lipids, vasculitis screen, coagulopathy screen
  • Structural imaging: MRI


No specific treatment exists although L-dopa may alleviate symptoms. Treatment is therefore supportive.