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
Core Pathophysiology
The fundamental problem in gastroparesis involves neuromuscular abnormalities affecting gastric motor function 1, 2:
- Failure of antral contractions and/or pyloric relaxation impedes gastric emptying, representing the main pathophysiological disturbance 1
- Damage to interstitial cells of Cajal (ICC) disrupts the underlying rhythmicity within gastrointestinal smooth muscle that generates normal gastric motility 2
- Loss of nitrergic inhibitory neurons has been documented in patients with idiopathic and diabetic gastroparesis 3
- Pyloric dysfunction manifests as pylorospasm, characterized by prolonged intermittent contractions and marked increases in baseline tone at the pylorus 1
Cardinal Symptoms
The symptom complex of gastroparesis includes 1:
- Nausea and vomiting (the predominant persistent symptoms in refractory cases) 1
- Early satiety
- Postprandial fullness
- Bloating
- Upper abdominal pain
A critical diagnostic challenge is that these symptoms overlap substantially with functional dyspepsia, making accurate diagnosis and treatment assessment difficult. 1
Major Etiologies
The causes of gastroparesis follow a clear distribution pattern 1, 2:
- Idiopathic gastroparesis accounts for approximately 50% of cases, with many likely representing post-infectious processes 4
- Diabetic gastroparesis represents approximately 25% of cases, affecting 20-40% of patients with long-standing type 1 diabetes 1, 2
- Post-surgical gastroparesis typically results from vagotomy (intended or unintended) during esophagectomy, gastrectomy, or fundoplication 2
- Medication-induced causes include opioids, anticholinergics, and GLP-1 receptor agonists 2
- Post-viral/post-infectious gastroparesis is usually self-limited 2
- Other causes include connective tissue disorders, vascular disorders, and neurodegenerative diseases 1
Diagnostic Requirements
A confirmed diagnosis of gastroparesis requires both characteristic symptoms AND objective documentation of delayed gastric emptying in the absence of mechanical obstruction. 5
The diagnostic approach must include 6, 2:
- Upper endoscopy first to exclude mechanical obstruction and inflammatory conditions 6, 2
- Gastric emptying scintigraphy performed for at least 2 hours, with 4-hour testing providing higher diagnostic yield and accuracy 6
- The radioisotope must be cooked into the solid portion of a standardized low-fat, egg white meal labeled with 99mTc sulfur colloid 6
- Medications affecting gastric emptying (prokinetics, opioids, anticholinergics) should be withdrawn 48-72 hours prior to testing 6
- Blood glucose should be controlled during testing, as hyperglycemia itself slows gastric emptying and can produce false positive results 6
Clinical Impact
Gastroparesis affects approximately 5 million U.S. adults and has substantial healthcare implications 1:
- Symptoms range from minimal daily impact to severe disability requiring frequent hospitalizations 7
- Gastric emptying rate accounts for at least one-third of the variance in postprandial glycemia in diabetic patients 1
- Delayed gastric emptying can cause "gastric hypoglycemia" in insulin-treated patients when nutrient delivery fails to match exogenous insulin action 1
- Patients with symptomatic gastroparesis utilize substantially more healthcare resources than diabetic patients without gastroparesis 1
Definition of Medically Refractory Disease
Medically refractory gastroparesis is defined as persistent symptoms (particularly nausea and vomiting) in the context of objectively confirmed gastric emptying delay, despite dietary adjustment and metoclopramide as first-line therapy. 1
A reasonable trial requires 1: