The pathologic hallmark of sporadic or idiopathic Parkinson disease is Synuclein-filled Lewy bodies in the nigrostriatal system However, synuclein can accumulate in many other parts of the nervous system, including the dorsal motor nucleus of the vagus nerve, basal nucleus of Meynert, hypothalamus, neocortex, olfactory bulb, sympathetic ganglia, and myenteric plexus of the gastrointestinal tract.