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Advanced Neurology Gastrointestinal symptoms in PD

Figure 1. Graphical summary of GI management in PD.

dopaminergic neurons in the SN region leads to the motor the medulla oblongata and the peripheral sensory nerves
[22]
symptoms of PD, while the GI symptoms are derived from and motor nerves innervating the pharyngeal muscle ,
pathological changes in the swallowing center, peripheral suggesting that central and peripheral mechanisms are
nerves that control the swallowing muscles, and enteric involved in the dysphagia of patients with PD.
nervous system (ENS). The retardation of GI motility leads to gastroparesis
In general, drooling is caused by increased salivary and constipation, and severe constipation leads to fecal
secretion or decreased swallowing. Patients with PD impaction and intestinal pseudo-obstruction. GI motility
often have reduced salivary secretion [8,19] . Pathological dysfunction is thought to be caused by pathological
studies have showed that LBs exist in the superior cervical changes of the ENS. The two main groups of ganglia in
ganglion, cervical sympathetic trunk, peripheral vagus the ENS are the intermuscular ganglia and submucosal
nerve, and submandibular gland, thereby damaging the ganglia [23,24] . Abnormal α-synuclein accumulation in the
salivary secretion . Therefore, dysphagia is considered ENS leads to slow GI movement. Pathological analysis of
[20]
the cause of excessive salivation in patients with PD. the GI symptoms of PD shows that the typical pathological
The pathophysiological mechanism of dysphagia in PD features are distributed from the gut to the brain, which
has not been fully clarified. The present studies suggest supports the suggestion that PD is a systemic disease. It
that both dopaminergic and non-dopaminergic systems should be noted that the pathological changes appear
are implicated in dysphagia. Many swallowing associated in the gut before the CNS, and the occurrence of GI
projection fibers converged on the dopaminergic basal symptoms such as constipation may occur decades before
[14]
ganglia system, which plays an important role in swallowing. the diagnosis of PD . Thus, it has been suggested that PD
Functional MRI has shown that both the putamen and may originate in the intestine.
globus pallidus are activated in healthy volunteers during In 2003, Braak et al. proposed that α-synuclein
swallowing [10,21] , confirming the important role of the basal accumulation, the typical pathohistological manifestation
ganglia nervous system in the swallowing function. Thus, of PD, affects the ENS (Stages 1 and 2) decades before
dopamine deficiency impairs the swallowing function of affecting the CNS (stages 3 and 4) [25,26] , indicating that
patients with PD, and dysphagia is relieved by L-DOPA the GI tract may be part of the course of PD. The Braak
preparation. Autopsy studies of patients with PD have staging system attracted wide attention to the pathological
found α-synuclein aggregation in the swallowing center of GI changes of patients with PD. It is well established that

Volume 1 Issue 1 (2022) 3 https://doi.org/10.36922/an.v1i1.9