Semantische Demenz

Abstract

Semantic dementia (SD) is a relatively rare primary degenerative brain disease, often with onset before the age of 65, which belongs to the group of frontotemporal lobar degenerations. The central characteristic of SD is a progressive loss of semantic knowledge with manifestation in aphasia as well as impaired face and object recognition. A reliable discrimination of SD from other neurodegenerative conditions, in particular from Alzheimer's disease, may be a challenge for neurologists as well as neuropsychologists. In the first place, a sound knowledge base is expected from the expert in order to minimize false diagnoses. To illustrate this, a detailed case history of a 55-year old patient is presented who was referred for an independent medical and neuropsychological examination for disability benefits. The referral question was Pick's disease. However, the clinical manifestation as well as the results of a comprehensive neuropsychological evaluation clearly indicated the diagnosis of SD with neuroimaging and neuropsychological evidence of marked right temporal lobe atrophy. The case history highlights a number of problems inherent in current practice of dementia assessment. For differential diagnosis of dementing conditions, a thorough neuropsychological assessment appears to be indispensable.