What a gastrointestinal biopsy can tell us about Parkinson's disease?

Background The intraneuronal inclusions called Lewy bodies and neurites, which represent the characteristic pathological changes in Parkinson's disease, are found in the enteric neurons in the great majority of parkinsonian patients. This observation led to a substantial amount of research over the last few years in order to develop a minimally invasive diagnostic procedure in living patients based on gastrointestinal (GI) biopsies. Purpose In this review, we will begin by discussing the studies that focused on the detection of Lewy bodies and neurites in GI biopsies, then broaden the discussion to the pathological changes that also occur in the enteric glial cells and intestinal epithelial cells. We conclude by proposing that a GI biopsy could represent a unique window to assess the whole pathological process of the brain in Parkinson's disease.