Corticobasal degeneration

Corticobasal degeneration (CBD) is an uncommon neurodegenerative disease and is one of the subset of taupathies.

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 life5, with the youngest reported case being 40 years of age 3.

Due to its myriad presentations which often crossover with other neurodegenerative condtions, corticobasal degeneration is challenging to diagnose5. 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 phenomenon5. In the broader spectrum of corticobasilar syndrome, patients often present with slowly progressive symptoms and signs including 1,2:

  • apraxia
  • dystonia
  • postural instability
  • akinetic-rigid syndrome
  • myoclonic jerks
  • cognitive impairment, often with pronounced frontal lobe signs 2
  • Alien limb phenomenon (believed to be due to supplementary motor area involvement) 1,2,4.

Unlike Parkinson disease, these symptoms are not ameliorated by levodopa 1

The characteristic histopathological findings are neuronal loss and numerous swollen 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 corticobasilar degeneration may be distinguishable from that of progressive supranuclear palsy. Patients with CBD tend to have atrophy in posteriolateral and medial frontal cortical regions, but relatively preserved brainstem anatomy5.

Research is ongoing regarding the use of techniques such as 3D volumetric MRI and diffusion tensor imaging in the evaluation of CBD5.

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.

There are no current drug therapies available to modify the course of CBD. Treatment is often focused on symptomatic relief, and supportive services such as speech and occupational therapy should not be overlooked5

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:

Neurodegenerative diseases

Neurodegenerative diseases are legion and their classification just as protean. A useful approach is to divide them according to underlying pathological process, although even using this schema, there is much overlap and thus resulting confusion.

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Article information

rID: 12988
Tag: cases
Synonyms or Alternate Spellings:
  • Cortical-basal ganglionic degeneration
  • Corticonigral degeneration with neuronal achromasia
  • Cortical-basal ganglionic degeneration (CBGD)
  • CBGD
  • Corticobasal degeneration (CBD)
  • corticobasal syndrome

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