Diagnostic staging of Parkinson’s disease: conceptual aspects

Insidious onset of mild, unspecific, sensitive, vegetative, psychopathological, cognitive and perceptive disturbances, i.e. visual and olfactory dysfunction, with a resulting change of personal behaviour, i.e. reduced stress tolerance, precede the initially intermittendly occurring motor symptoms in patients with Parkinson’s disease (PD). Novel neuropathological findings suggest an expansion pattern of the neurodegenerative process beyond the nigral dopaminergic neurons with the initial event located outside the brain. We related these clinical observations of premotor symptoms of PD to this novel neuropathological concept of emerging neurodegeneration, which starts in the enteric system and then rises via spinal cord and brainstem to nigral and subsequent cortical neurons. We describe an initial premotor phase, which starts in non dopaminergic areas, and subdivide it according to the onset of gastrointestinal and brainstem associated and sensory deficits. Then motor symptoms occur and increase in the further course of PD similar to the Hoehn and Yahr stages. Our proposed diagnostic concept aims to an earlier diagnosis of PD. In addition, attention should be given to diseases of the gastrointestinal tract and psychosomatic disorders, all of which, if not or ineffectively treated, may contribute to an enhanced vulnerability for PD. The concept takes into account, that an as far unknown pathogen, e.g. viral infection or nutritional component, that meets a genetically predisposed person with a long lasting disturbed enteric nervous system, may be at risk for PD. Earlier premotor diagnosis of PD will enable more convincing future results on the therapeutic efficacy of neuroprotective compounds.