Classification of Dementia
There are many ways to subdivide dementias. The choice of a classification depends on the intention and the tools of the examiner and the data that can be acquired. In a neuropathological classification different means of separating subgroups are availabl
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Classification of Dementia
3.1
Considerations
There are many ways to subdivide dementias. The choke of a classification depends on the intention and the tools of the examiner and the data that can be acquired. In a neuropathological classification different means of separating subgroups are available compared with clinical or laboratory examinations. The pathologist will favor a distinction on the
grounds of structures involved, the presence of microscopic abnormal structures, and the immunoreactivity of such structures (Diagram 3-1). In neuroradiology dementias have to be classified in a way that makes sense to both the radiologists and the clinicians and that allows recognition of image patterns of the various subforms. The first distinction that can be made is between static and progressive forms of dementia. In ac-
Huntington's d si ease Spinocerebellar ataxia Dementia lacking specific pathology
Cytoskeletal indusions ALS dementia Neuroaxonal dystrophy Mu ltiple system atrophy
Tau-indusion Lewy body disease Ballooned neurons Familial ALS
Diagram 3.1. A possible classification of neurodegenerative disorders based on histopathological data. This diagram is incomplete and does not include other forms of immunoreactivity, such as anti-ubiquitin and anti a -synuclein reactivity. This is an example of a classification that is not useful for clinical and neuroradiological purposes
Douplet PHF tau : glial and neuronal Alzheimer's disease Down synd rome Postencephalic PD Guam PD dementia Familial FTD
J. Valk et al., Magnetic Resonance in Dementia © Springer-Verlag Berlin Heidelberg 2002
Pick's disease Progressive su pranuclar palsy Corticobasal degeneration Frontotemporal dementia- l 7
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___________________________ Classification of Dementia quired forms of dementia, for example after trauma or encephalitis, a cognitive and/or emotional defect may remain, with little change thereafter. From a clinical point of view one mayaiso distinguish eortieal from subeortieal dementias. In the cortical type focal cortical symptoms are first to present, while in the second type slowing down of mental processes is considered to be a key issue. Though the validity of this distinction is questioned, from a pragmatic point of view it may still be useful. The classic exampIes of these two subtypes are Alzheimer's disease and Binswanger's disease. When clinical symptoms and neuropsychological data are included in a classification other symptoms have to be included as weIl. Such issues are behavioral changes, subtypes of language disorders (for example semantic aphasia, fluent and non-fluent types of aphasia), prosopagnosia (difficulty in recognizing faces), spatial orientation disorders, alien limb syndrome, the presence of extrapyramidal signs with symmetric or asymmetric presentation, the presence of motor neuron disease, the presence of gaze abnormalities or ophthalmoplegias and the involvement of other organs. Each one of these features may be indieative of a certain diagnosis or subtype of dementia. Genetically one may
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