The vast majority of cases are sporadic, although a number of familial cases have been described 2. Patients are usually elderly, with the youngest reported case being 40 years of age 3.
Patients present with slowly progressive symptoms and signs tyically including 1-2:
In addition a degree of cognitive impariment is common, often with pronounced frontal lobe sign 2.
Alien limb phenomenon is also frequently observed, and is 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
- 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
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 2.
Treatment and prognosis
Unfortunately 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:
- 1. Tokumaru AM, O'uchi T, Kuru Y et-al. Corticobasal degeneration: MR with histopathologic comparison. AJNR Am J Neuroradiol. 17 (10): 1849-52. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 2. Esiri MM, Trojanowski JQ. The neuropathology of dementia. Cambridge Univ Pr. (2004) ISBN:0521819156. Read it at Google Books - Find it at Amazon
- 3. Moretti R. Corticobasal ganglionic degeneration, cognitive and functional aspects. Nova Science Pub Inc. (2005) ISBN:1594543887. Read it at Google Books - Find it at Amazon
- 4. Tiwari D, Amar K. A case of corticobasal degeneration presenting with alien limb syndrome. Age Ageing. 2008;37 (5): 600-1. doi:10.1093/ageing/afn103 - Pubmed citation
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.
neurodegenerative MRI brain (an approach)
- measurements and ratios
- midbrain to pons area ratio (for PSP)
- Magnetic Resonance Parkinsonism Index (MRPI) (for PSP)
- frontal horn width to intercaudate distance ratio (FH/CC) (for Huntington disease)
- intercaudate distance to inner table width ratio (CC/IT) (for Huntington disease)
- scoring systems
- measurements and ratios
- typical/classical Alzheimer disease
- variant (e.g. posterior cortical atrophy)
- chronic traumatic encephalopathy (CTE)
- corticobasal degeneration
- frontotemporal lobar degeneration (FTLD) (not all are tau)
- Pick disease
- progressive supranuclear palsy (PSP)
- Alzheimer disease
- cerebral amyloidosis
- spinocerebellar ataxias
- Huntington disease
- hereditary spastic paraplegia
- amyotrophic lateral sclerosis (ALS)
- clinically unclassifiable parkinsonism (CUP)
- Unverricht-Lundborg disease
- prion diseases (not always included as neurodegenerative)