Abstract

Parkinson’s disease is a systemic disorder with widespread and early α-synuclein pathology in the autonomic and enteric nervous systems, which is present throughout the gastrointestinal canal prior to diagnosis. Gastrointestinal and genitourinary autonomic symptoms often predate clinical diagnosis by several years. It has been hypothesized that progressive α-synuclein aggregation is initiated in hyperbranched, non-myelinated neuron terminals, and may subsequently spread via retrograde axonal transport. This would explain why autonomic nerves are so prone to formation of α-synuclein pathology. However, the hypothesis remains unproven and in vivo imaging methods of peripheral organs may be essential to study this important research field. The loss of sympathetic and parasympathetic nerve terminal function in Parkinson’s disease has been demonstrated using radiotracers such as 123I-meta-iodobenzylguanidin, 18F-dopamine, and 11C-donepezil. Other radiotracer and radiological imaging methods have shown highly prevalent dysfunction of pharyngeal and esophageal motility, gastric emptying, colonic transit time, and anorectal function. Here, we summarize the methodology and main findings of radio-isotope and radiological modalities for imaging peripheral pathology in Parkinson’s disease.

Highlights

  • Parkinson’s disease (PD) is a systemic disorder with widespread αsynuclein pathology in the peripheral and enteric nervous systems.[1]

  • Most RBD patients, known to be prodromal PD or DLB in the majority of cases,[29] show decreased cardiac MIBG uptake more similar to later stage PD patients, and clearly surpassing the signal reduction seen in newly diagnosed PD patients without RBD.[30, 31]

  • Two studies reported similar reductions in cardiac MIBG uptake of PD patients, heart failure patients, and diabetic patients with neuropathy, but only the PD patients displayed a reduction in thyroid uptake.[38, 43]. These findings suggest that thyroid sympathetic denervation may be more specific for PD, and may enhance the specificity of MIBG imaging for correctly diagnosing PD

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Summary

Introduction

Parkinson’s disease (PD) is a systemic disorder with widespread αsynuclein pathology in the peripheral and enteric nervous systems.[1]. Most RBD patients, known to be prodromal PD or DLB in the majority of cases,[29] show decreased cardiac MIBG uptake more similar to later stage PD patients, and clearly surpassing the signal reduction seen in newly diagnosed PD patients without RBD.[30, 31] A recent 11CHED PET study demonstrated that PD patients with mildly affected baseline scans showed progressive decline preferentially in inferolateral segments.

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