Constipation can be one of the first symptoms, occurring when Lewy body lesions first appear on the vagal nerve's dorsal motor nucleus
Histopathologic lesions in brain of zebu with spongiform encephalopathy and cow with bovine spongiform encephalopathy, Switzerland, 2004 * Site Cow Zebu Brainstem Dorsal motor nucleus
of vagus nerve (+) (++) Nucleus of spinal tract of trigeminal (++) (+++) nerve Nucleus of hypoglossal nerve (+) (++) Reticular formation (++) (++) Nucleus of solitary tract (++) (+++) Vestibular nuclei (++) (+) to (++) Olivary nuclei (++) (++) Cerebellar cortex (-) (+) Midbrain (substantia grisea centralis) (+) to (++) (++) to (+++) Thalamus (++) (++) to (+++) Hippocampus n.
Examination of the brains of these animals showed not only nigral cell loss with a corresponding striatal dopamine depletion but also neurodegeneration in the locus coeruleus, dorsal motor nucleus
of the vagus, and the nucleus basalis of Meynert, a pattern of cell loss that is strikingly similar to that seen in Parkinson's disease and is not observed in any other of the toxicant-induced animal models of Parkinson's disease.
Most authors agree that the reduction of RRIV in PD is due to degeneration of the dorsal motor nucleus
of the vagus nerve.