Gut dysfunction in Parkinson's disease

Table 1 Gut pathology in Parkinson’s disease

Distribution of gut pathology	Pathology spreading from the gut	Gut microbiota
Rostrocaudal gradient of α-synuclein pathology	Crossing the gut barrier	Modulation of gut-brain axis
Place of colon and vermiform appendix	Dual-hit hypothesis	Helicobacter pylori and small intestinal bacterial overgrowth
	Prion-like propagation	Clinical phenotypic correlation

Table 2 Sialorrhea

Mechanism	Treatment
Swallowing dysfunction	Oral Glycopyrrolate
Abnormal head posture	Sublingual Ipratropium bromide spray
Unintentional mouth opening due to hypomimia	Intra-oral Tropicamide films
	Behavioral modification
	Intra-salivary gland Botulinum neurotoxin injection
	Radiotherapy

Table 3 Dysphagia

Evaluation	Treatment
Bedside screening	Compensatory maneuvers
Cough reflex testing	Rehabilitation maneuvers
Modified barium swallow studies	Expiratory muscle strength training
Videofluoroscopy	Video-assisted swallowing therapy
Manometry	Rotigotine transdermal patch
Fiberoptic endoscopic evaluation of swallowing	Percutaneous endoscopic gastrostomy placement

Table 4 Gastroparesis

Evaluation	Treatment	Modifications of dopaminergic agents
Gastric emptying scintigraphy	Domperidone	Orally dissolving or soluble formulations
13C-sodium octanoate breath test	Nizatidine	Levodopa-carbidopa intestinal gel
Electrogastrography	Ghrelin agonist	Rotigotine patch
	Botulinum neurotoxin injection into the pyloric sphincter	Subcutaneous Apomorphine
	STN DBS
	Gastric electrical stimulation

STN: Subthalamic nucleus; DBS: Deep brain stimulation.

Table 5 Constipation and defecatory dysfunction

Mechanism	Evaluation	Treatment
Slow transit constipation	Radiopaque marker study for colonic transit	High fiber diet, psyllium, proper fluid intake
	Wireless motility capsule	Adjustment of anticholinergics and dopaminergic agents
		Macrogol1
		Lubiprostone2
Dyssynergic defecation	Anorectal manometry	Biofeedback therapy
	Rectal balloon expulsion	Botulinum neurotoxin injection into the puborectalis
	Defecography

¹Macrogol-polyethylene glycol (an osmotic laxative);

²Lubiprostone-chloride channel activator (increases fluid secretion in the intestine).