[Dementias with Lewy bodies]

Dementias with Lewy bodies are no rare cause of cognitive and motor impairments in old age. Neuropathologically, they must be distinguished into diffuse Lewy body disease resp. dementia with Lewy bodies, Parkinson's disease with concomitant Alzheimer's pathology, and the Lewy body variant of Alzheimer's disease according to extent and concomitant pathology. The most reliable diagnostic features of dementia with Lewy bodies are fluctuating disturbances of cognition and consciousness, visual disorders (hallucinations, visuoperceptive and visuoconstructive impairments), and early extrapyramidal signs of the hypokinetic-rigid type with a propensity to frequent falls. The pertinent diagnostic criteria are the consensus criteria according to McKeith et al. Additional contributions are to be expected by functional neuroimaging (SPECT, PET) and CSF examination (homovanillic acid). However, even assuming the most favorable conditions a diagnostic accuracy of 85 % is presently hard to achieve. Particularly, as is demonstrated using a case example, reliable antemortem diagnosis of Lewy body variant of Alzheimer's disease is hardly possible. Clinically, this group of diseases is important, since increased neuroleptic sensitivity must be taken into account and modern central cholinergic agents seem to be a promising therapeutic option.