Stanley Fahn Lecture 2005: The staging procedure for the inclusion body pathology associated with sporadic Parkinson's disease reconsidered.

The synucleinopathy known as sporadic Parkinson's disease (PD) is a multisystem disorder that severely damages predisposed nerve cell types in circumscribed regions of the human nervous system. A recent staging procedure for the inclusion body pathology associated with PD proposes that, in the brain, the pathological process (formation of proteinaceous intraneuronal Lewy bodies and Lewy neurites) begins at two sites and continues in a topographically predictable sequence in six stages, during which components of the olfactory, autonomic, limbic, and somatomotor systems become progressively involved. In stages 1 to 2, the Lewy body pathology is confined to the medulla oblongata/pontine tegmentum and anterior olfactory structures. In stages 3 to 4, the substantia nigra and other nuclei of the basal mid- and forebrain become the focus of initially subtle and, then, severe changes. During this phase, the illness probably becomes clinically manifest. In the final stages 5 to 6, the lesions appear in the neocortex. This cross-sectional study originally was performed on 168 autopsy cases using material from 69 incidental cases and 41 clinically diagnosed PD patients as well as 58 age- and gender-matched controls. Here, the staging hypothesis is critically reconsidered and discussed.