Pathophysiology of Sporadic Parkinson's Disease

Sporadic Parkinson's disease is a multisystem disorder that involves predisposed nerve cell types in circumscribed regions of the entire human nervous system (peripheral, enteric, and central nervous systems). A recent staging procedure for the pathological process proposes that, in the brain, the formation of intraneuronal Lewy bodies and Lewy neurites begins at two sites and continues in a topographically predictable sequence in 6 stages, during which components of the olfactory, autonomic, limbic, and somatomotor systems become progressively involved. In stages 1 2, the Lewy body pathology is confined to the medulla oblongata/pontine tegmentum and anterior olfactory structures. In stages 3-4, the substantia nigra, other nuclei of the basal mid- and forebrain, and the mesocortex become the focus of initially subtle and, then, severe changes. During this phase, the illness probably becomes clinically manifest. In the final stages 5-6, the lesions appear in the neocortex.