Cortical Basal Ganglionic Degeneration

Updated: Jun 03, 2014
  • Author: A M Barrett, MD; Chief Editor: Selim R Benbadis, MD  more...
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Overview

Background

Cortical basal ganglionic degeneration (CBGD), a sporadic neurodegenerative tauopathy, may be considered both a syndrome of characteristic movement and cognitive dysfunction (corticobasal syndrome) and a pathologically defined disease. The corticobasal syndrome is defined by progressive dementia, parkinsonism, and limb apraxia, but these may occur as a result of a number of pathologic entities. The most characteristic are Pick complex disorders (see Pick Disease), but Alzheimer disease and even rare disorders such as CNS Whipple disease and Niemann-Pick type C can be associated with corticobasal syndrome. Histopathologically identifiable CBGD can also present clinically as primary progressive aphasia [1] or primary progressive apraxia in patients who had no prominent movement disorders earlier in their lives.

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Pathophysiology

Both cortical and subcortical abnormalities are seen. The disorder is currently classified as a 4-repeat tauopathy, and although tau-immunoreactive neuronal and glial inclusions may be seen in Pick disease, progressive supranuclear palsy (PSP), and even Alzheimer disease, these disorders may differ in the proportions of 4-repeat as compared with 3-repeat microtubule-associated tau protein isoforms, with CBGD and progressive supranuclear palsy being the 2 predominantly 4-repeat tauopathies. Both neurons and glial cells are involved, and both cortical (pyramidal and nonpyramidal) neurons, as well as subcortical regions. Ballooned swollen neurons with loss of cytoplasmic staining (ie, achromasia) are a supportive feature when present in the cortex and the basal ganglia. CBGD may be associated with both cortical and subcortical neuronal loss, neuronal and glial tau pathology (including astrocytic plaques); cortical loss, predominantly affecting motor and premotor regions, [2] may distinguish this disorderfrom progressive supranuclear palsy.

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Epidemiology

Frequency

United States

Data on incidence and prevalence of this disorder are still being collected. Clinical reports have multiplied geometrically in the last 20 years, suggesting either that clinical evaluation has become more sensitive or that the syndrome is appearing more frequently. It is estimated to account for about 5% of cases of parkinsonism seen in clinics that specialize in movement disorders, or 0.62-0.92 per 100,000 per year, with an estimated prevalence of 4.9-7.3 per 100,000. [3] A study in Eastern European and Asian subjects reported an incidence of 0.02 case per 100,000 people. [4]

Mortality/Morbidity

This is a progressive neurodegenerative disorder with increasing levels of disability and loss of independence. Individuals with CBGD do not usually die of the disorder itself but of complications of the bedridden state, such as aspiration pneumonia and infections, within 10 years of onset.

Race

No racial predilection is known.

Sex

In several studies, CBDG was reported to be more common in women. [3]

Age

Typically, CBGD presents between the ages of 50 and 80 years. No pathologically confirmed case of CBGD has ever been published with onset before 45 years, but the author of this article personally reviewed medical records for a man who died with pathologically confirmed CBGD whose first symptoms occurred at age 41 years, and a patient with the onset of corticobasal syndrome at age 28 years has been reported. [5]

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