Our Parkinson's Place: Scientific Discovery May Change Treatment of Parki.
Parkinson's disease becomes apparent only after substantial loss (>60%) of the dopamine neurons in the substantia nigra. By this time there has already been widespread neural inclusion formation in the peripheral and central nervous system of patients with the disease, although this has only been recognized more recently. Degeneration in these widespread regions of the peripheral and central nervous system is now known to impact on disease symptoms, progression and treatment over time.
Function and Location of Substantia Nigra: A Diagrammatic Explanation