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Advanced Neurologyurology
Advanced Ne Gastrointestinal symptoms in PD

the central nervous system (CNS) through the vagus nerve. 2.3. Gastroparesis
Recent research has suggested that the gut microbiota Gastroparesis refers to the delayed emptying of solid food
may contribute to PD ; however, the specific underlying without mechanical obstruction. The clinical manifestations
[6]
mechanism remains elusive. Therefore, it is of great of gastroparesis include abdominal distension, hiccups,
significance to focus on the GI symptoms and pathological nausea, and vomiting. Impaired gastric emptying caused
changes in patients with PD, and consequently develop by gastric dysmotility is common in patients with PD, but
standardized identification and management. Herein, not all patients display subjective symptoms. Up to 50%
we systematically elaborate the clinical manifestations, of patients with PD have abdominal distention, and 15%
pathogenesis, diagnosis, and management of GI symptoms have nausea and vomiting . Gastroparesis may occur in
[14]
in patients with PD (Figure 1). the early stage of PD or even before the PD diagnosis. The
2. Clinical manifestation and epidemiology prevalence of gastroparesis seems to be higher in the later
stages of PD, and the severity of gastroparesis is correlated
2.1. Drooling with motor symptoms. The occurrence of gastroparesis is
Excessive salivation is a known issue in PD that has a also related to the slowing down of GI muscle movement.
negative impact on social interactions and may even Furthermore, there are a few reported cases of rapid gastric
lead to depression. Studies have shown that more than emptying in PD, which may be due to uncoordinated action
one-third of patients with advanced PD have excessive of GI muscle groups. Gastroparesis leads to decreased
salivation, which the 8-item PD questionnaire indicates is efficacy or dyskinesia, which increases the difficulty of
[15]
significantly related to decreased quality of life . Excessive treatment .
[7]
salivation is also caused by swallowing dysfunction. The 2.4. Constipation
pathological changes of CNS structures and innervating
nerves of the oropharyngeal muscle groups are responsible Constipation is a common GI symptom that is
for swallowing dysfunction, which results in saliva characterized by reduced defecation frequency, firm stools,
accumulation and excessive salivation. A retrospective and dysphasia. At present, the diagnosis of constipation is
analysis of 728 patients with PD demonstrated that the mainly based on the Rome IV criteria and the patient’s
prevalence of dysphagia was higher among patients with subjective feeling. For constipation to be diagnosed, the
excessive salivation than in patients without excessive symptoms must have been present for at least 6 months
salivation [7,8] , which further suggests that the excessive and must have been experienced within the past 3 months.
salivation may be caused by dysphagia. The study also A patient is diagnosed with constipation if they have two or
reported that the rate of salivation increases with age. more of the following defecation-related manifestations in
The reason and potential mechanism for this increased more than 25% of their defecations: Straining, massive or
salivation warrant further investigation. hard feces, incomplete bowel movement, anal obstruction,
manual evacuation, and less than 3 spontaneous defecations
2.2. Dysphagia per week . The estimated prevalence of constipation
[16]
[17]
Around 35% of patients with PD report having subjective worldwide is 15–20% in people older than 60 years and
symptoms of dysphagia during the course of their disease, 20.0–37.3% in people older than 84 years [17,18] . In patients
and more than 80% of patients are diagnosed with with PD, constipation is very common, with a prevalence
dysphagia by objective measures [9,10] . Dysphagia is related of around 80% [1-4] . In most cases, constipation significantly
to movement disorder of the oropharyngeal muscles, reduces the quality of life. In addition, constipation in
which leads to slow and uncoordinated swallowing action. older adults can lead to fecal impaction and intestinal
However, the etiopathogenesis of dysphagia is unclear. pseudo-obstruction, which collectively form a serious
Swallowing dysfunction is considered to be caused by issue. Constipation can precede motor symptoms by up to
degeneration of the basal ganglia, substantia nigra (SN) 20 years, indicating that constipation could be a warning
region, and brainstem [10,11] . Dysphagia leads to reduced for the onset of PD. Multiple prospective and retrospective
eating, malnutrition, and even aspiration pneumonia, studies have shown that people with constipation have a
which are important causes of death in patients with higher risk of PD development.
PD [11-13] . The prevalence and severity of dysphagia increase 3. Pathophysiology of GI symptoms
significantly as PD progresses. As dysphagia involves lesions
in the SN region and muscle dyskinesia, some scholars The typical neuropathological manifestations of PD
believe that dysphagia should be classified as an atypical are abnormal α-synuclein aggregation and Lewy body
motor symptom. The application of antiparkinsonian (LB) formation, resulting in the loss of dopaminergic
drugs partially improves the swallowing function. neurons in the SN region. It is well known that the loss of

Volume 1 Issue 1 (2022) 2 https://doi.org/10.36922/an.v1i1.9