Summary

Lewy bodies are an important histological feature of several neurodegenerative diseases typified by idiopathic Parkinson's disease. With the increasing recognition of dementia associated with Lewy bodies in cortical neurons it is desirable to have a better understanding of the biogenesis and function of these neuronal inclusions. There is considerable indirect evidence, based on immunohistochemical identification of constituent proteins, that the Lewy body is a structural manifestation of a cytoprotective cell response. When encountered in diagnostic practice a distinction is presently made between primary Lewy body disorders, where the Lewy body is felt to be closely related to the pathogenesis of disease, and coincidental Lewy body disorders where Lewy bodies are inconsistently associated with other pathological processes. This division is still arbitrary and based on relative ignorance about the functional biology of the Lewy body phenomenon.

Introduction

An important histological characteristic of idiopathic Parkinson's disease is the presence of intraneuronal inclusions termed Lewy bodies. Recent morphological and cell biological studies have also characterized Lewy bodies in a variety of disorders, particularly in the cerebral cortex in association with dementia. These observations have prompted important considerations as to the biological function of the Lewy body and whether the presence of Lewy bodies can be used to define specific types of neurodegenerative disease.

Functional biology of Lewy bodies

There are two distinctive morphological types of Lewy body, the classical (brainstem) type and the cortical type (Lowe, 1994). In addition, so-called pale bodies are felt to be a possible precursor of Lewy bodies (Dale et al., 1992; Hayashida et al., 1993).