Corticobasal degeneration

Last revised by Dr Rohit Sharma on 28 Dec 2021

Corticobasal degeneration is an uncommon neurodegenerative disease and is one of the subset of tauopathies.

The vast majority of cases are sporadic, although a number of familial cases have been described 2. Patients are usually in the fifth to seventh decades of life 5, with the youngest reported case being 40 years of age 3.

Due to its myriad presentations which often crossover with other neurodegenerative conditions, corticobasal degeneration is challenging to diagnose 5. The classical "corticobasal syndrome" is a progressive disorder with various asymmetric movement abnormalities, myoclonus, as well as cortical signs including ideomotor apraxia and alien limb phenomenon 5. Corticobasal syndrome represents the clinical syndrome of the pathologically confirmed corticobasal degeneration. Despite extensive efforts in developing diagnostic criteria, clinical diagnosis does not always correlate with the pathological diagnosis.

In the broader spectrum of corticobasal syndrome, patients often present with slowly progressive symptoms and signs including 1,2:

  • akinetic-rigid syndrome, which unlike in Parkinson disease is not ameliorated by levodopa 1
  • limb apraxia
  • dystonia
  • myoclonic jerks
  • postural instability and falls
  • cognitive impairment, often with pronounced frontal lobe signs 2
  • cortical sensory loss
  • alien limb phenomenon 1,2,4
  • cognitive impairment

The characteristic histopathological findings are neuronal loss and numerous "ballooned" achromatic neurons 1. Although these features are seen throughout the brain, certain regions are more severely affected. They include:

  • frontoparietal cortex
  • subcortical structures
    • striatum
    • substantia nigra

MRI is the modality of choice for assessing corticobasal degeneration, although similar findings can, only to a certain degree, be seen on CT.

Typical findings include 1,2:

  • asymmetric cortical atrophy
  • bilateral atrophy of the basal ganglia
  • atrophy of the corpus callosum 2
  • T2 hyperintensity
    • subcortical white matter of affected gyri
    • posterolateral putamen

The pattern of atrophy in corticobasal degeneration may be distinguishable from that of progressive supranuclear palsy. Patients with corticobasal degeneration tend to have atrophy in posterolateral and medial frontal cortical regions, but relatively preserved brainstem anatomy 5.

Research is ongoing regarding the use of techniques such as 3D volumetric MRI and diffusion tensor imaging 5.

SPECT and PET studies tend to demonstrate hypometabolism in the superior parietal and superior frontal areas, as well as (but less frequently) in the basal ganglia and thalamus 2,5. Early metabolic changes tend to be asymmetrical similar to the clinical presentation. 

There are no current drug therapies available to modify the course of corticobasal degeneration. Treatment is often focused on symptomatic relief. Supportive services such as speech and occupational therapy should not be overlooked 5

Unfortunately, the overall prognosis is poor, with patients demonstrating gradual neurological decline. Death occurs typically 5 to 10 years after the diagnosis is first made 3.

Clinically there is overlap with 1:

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