What is Gastroparesis
Gastroparesis is a chronic gastrointestinal syndrome defined by symptomatic delayed gastric emptying of solid food, with or without delayed liquid emptying, occurring in the absence of mechanical gastric-outlet obstruction. 1
Definition and Core Pathophysiology
Gastroparesis represents a chronic neuromuscular disorder where the stomach fails to empty properly despite no physical blockage 1, 2. The condition results from failure of antral contractions and/or pyloric relaxation that impedes gastric emptying 1. The underlying mechanisms are multifactorial and include:
- Antral hypomotility - weakened contractions of the lower stomach that normally propel food forward 1
- Pyloric dysfunction - the pyloric sphincter (approximately 1.2 cm zone of thickened muscle between stomach and duodenum) fails to relax appropriately, characterized by prolonged intermittent contractions and marked increases in baseline tone 1
- Impaired gastric accommodation - the stomach's inability to relax and expand to receive food 3
- Loss of interstitial cells of Cajal - specialized pacemaker cells that coordinate gastric contractions 4
- Reduction in nitrergic inhibitory neurons - nerve cells responsible for relaxation signals 4
Cardinal Symptoms
The hallmark symptoms include 1, 2, 5:
- Nausea and vomiting - typically the most predominant and persistent symptoms in refractory cases 5
- Early satiety - inability to finish a normal-sized meal 5
- Postprandial fullness - uncomfortable sensation of fullness persisting after eating 5
- Bloating - subjective sensation of abdominal distension 5
- Upper abdominal pain - particularly epigastric discomfort 1, 5
- Weight loss and malnutrition - in more severe cases 5
A critical caveat: these symptoms overlap significantly with functional dyspepsia, making accurate diagnosis challenging without objective testing. 1
Common Etiologies
The most frequent causes are 1, 2:
- Diabetic gastroparesis - accounts for approximately 25% of cases, occurring in 20-40% of patients with long-standing type 1 diabetes and other complications 1, 2
- Idiopathic gastroparesis - represents nearly 50% of cases, with many likely representing post-infectious processes 6
- Post-surgical gastroparesis - typically due to partial or complete vagotomy (intended or unintended during esophagectomy, Billroth II gastrectomy, fundoplication, or hernia repair) 1
- Post-infectious - following viral gastroenteritis 3
- Medication-induced - particularly from opioids and GLP-1 agonists 5
Less common causes include connective tissue disorders, autoimmune disorders, ischemia, neurodegenerative disorders (Parkinson disease), and myopathies (scleroderma, amyloidosis) 6, 7.
Diagnostic Requirements
A confirmed diagnosis requires three essential components: 2
- Appropriate symptoms as described above 2
- Documented delayed gastric emptying on objective testing - symptoms alone are inadequate as they correlate poorly with the degree of gastric emptying delay 8, 5
- Absence of mechanical obstruction - upper endoscopy must be performed first to exclude structural causes including mechanical obstruction, inflammatory conditions, or malignancy 2
The gold standard diagnostic test is gastric emptying scintigraphy performed for a minimum of 4 hours using a standardized low-fat, egg white meal labeled with 99mTc sulfur colloid 8, 2. Alternative testing includes 13C-octanoate breath testing, which is non-radioactive and correlates well with scintigraphy 8, 2.
Clinical Impact
Gastroparesis is estimated to affect approximately 4% of the population 9. The condition can range from minimal impact on daily activities to severe disability requiring frequent hospitalizations 9. The disease significantly reduces quality of life and generates substantial healthcare expenditure due to its chronic, often refractory nature 7.