GASTROPARESIS
Definition
Gastroparesis is a chronic disorder of delayed gastric emptying in the absence of mechanical obstruction, associated with upper gastrointestinal symptoms.
Key diagnostic triad
- Typical symptoms
- Objective delay in gastric emptying
- No mechanical obstruction
Epidemiology
- Female predominance (≈70%)
- Increasing incidence due to:
- Diabetes mellitus
- Post-surgical states
- Medication-induced causes
- Up to 30–40% cases are idiopathic
Normal Gastric Physiology
Gastric emptying depends on coordinated function of:
- Fundic accommodation (vagal mediated)
- Antral peristalsis
- Pyloric relaxation
- Duodenal feedback
Cellular Level
- Interstitial cells of Cajal (ICC) = gastric pacemaker
- Nitric oxide (NO) → pyloric relaxation
- Cholinergic pathways → antral contraction
Loss of ICCs and impaired NO signaling are central in gastroparesis.
Pathophysiology
Core Mechanisms
|
Mechanism |
Effect |
|
Vagal neuropathy |
↓ Fundic relaxation |
|
ICC loss |
↓ Gastric slow waves |
|
Pyloric dysfunction |
↑ Outflow resistance |
|
Autonomic dysfunction |
Disordered motility |
|
Smooth muscle fibrosis |
Weak antral pump |
Etiology
1. Diabetic Gastroparesis
- Long-standing diabetes
- Poor glycemic control
- Mechanism:
- Autonomic neuropathy
- Oxidative stress
- ICC destruction
Acute hyperglycemia (>200 mg/dL) independently delays gastric emptying
2. Idiopathic
- Often post-viral
- Female predominance
- Better prognosis than diabetic
3. Postsurgical
- Vagal nerve injury
- Surgeries:
- Fundoplication
- Bariatric surgery
- Esophagectomy
- Gastric surgery
4. Medication-Induced
|
Drug Class |
Examples |
|
Opioids |
Morphine, fentanyl |
|
Anticholinergics |
TCAs, antihistamines |
|
GLP-1 agonists |
Liraglutide, semaglutide |
|
Calcium channel blockers |
Verapamil |
|
Dopamine agonists |
Levodopa |
|
Cannabinoids |
Chronic cannabis use |
5. Systemic & Neurological Diseases
- Parkinson disease
- Multiple sclerosis
- Amyloidosis
- Scleroderma
- Hypothyroidism
- Chronic kidney disease
Clinical Features
Cardinal Symptoms
|
Symptom |
Frequency |
|
Nausea |
+++ |
|
Vomiting (undigested food) |
+++ |
|
Early satiety |
++ |
|
Post-prandial fullness |
++ |
|
Bloating |
++ |
|
Epigastric pain |
+ |
Vomiting of food eaten >6–8 hours earlier is classical
Complications
- Malnutrition
- Weight loss
- Electrolyte imbalance
- Aspiration pneumonia
- Poor glycemic control
- Bezoar formation
Diagnosis
Step 1: Exclude Mechanical Obstruction
- Upper GI endoscopy
- CT abdomen if needed
Step 2: Demonstrate Delayed Gastric Emptying
Gold Standard: Gastric Emptying Scintigraphy (GES)
- Standardized low-fat solid meal
- Imaging at 0, 1, 2, and 4 hours
Diagnostic Criteria
|
Time |
Retention |
|
2 h |
>60% |
|
4 h |
>10% |
Alternative Tests
|
Test |
Comment |
|
13C breath test |
Radiation-free |
|
Wireless motility capsule |
Whole gut transit |
|
Antroduodenal manometry |
Research/complex cases |
Severity Grading (ACG)
|
Grade |
Description |
|
Mild |
Controlled with diet |
|
Moderate |
Requires medication |
|
Severe |
Refractory, hospital dependent |
Management – STEPWISE
1. General Measures (Foundation)
Glycemic Control (Diabetics)
- Target glucose: 140–180 mg/dL
- Avoid acute hyperglycemia
Dietary Modification (Most Important Non-Drug Therapy)
|
Recommendation |
|
Small frequent meals |
|
Low-fat |
|
Low-fiber |
|
Soft / pureed food |
|
Liquid calories preferred |
Fat and fiber delay gastric emptying
2. Pharmacological Therapy
Prokinetics – Comparative Table
|
Parameter |
Metoclopramide |
Domperidone |
Erythromycin |
Levosulpiride |
|
Regulatory Status |
Only FDA-approved drug for gastroparesis |
Not FDA approved (restricted in US) |
Not approved for gastroparesis (off-label use) |
Not FDA approved (widely used in India) |
|
CNS Side Effects |
Yes (crosses BBB) • Dystonia • Parkinsonism • Tardive dyskinesia |
Minimal (does not cross BBB significantly) |
None specific |
Low but possible EPS |
|
Serious Warning |
⚠ Black box warning: Tardive dyskinesia ➡ Use ≤12 weeks |
QT prolongation, arrhythmia risk |
QT prolongation, drug interactions (CYP3A4) |
Hyperprolactinemia, QT prolongation |
|
Hyperprolactinemia |
Yes |
Yes |
No |
Yes (more common) |
|
Tachyphylaxis |
No |
No |
Yes (within 2–4 weeks) |
No |
|
ICU Role |
NG feeding intolerance |
Limited |
Very useful for feeding intolerance |
Rare in ICU |
B. Antiemetics (Symptomatic)
- Ondansetron
- Prochlorperazine
- Promethazine
Do not improve emptying – symptom control only
C. Neuromodulators (Pain-Predominant)
- Low-dose TCAs (nortriptyline)
- Mirtazapine (helpful for nausea + appetite)
3. Endoscopic & Surgical Therapies (Refractory Disease)
Gastric Electrical Stimulation (GES)
- Indicated for:
- Refractory diabetic gastroparesis
- Improves nausea/vomiting
- Limited effect on emptying
Pyloric Interventions (Emerging )
|
Technique |
Comment |
|
G-POEM |
Promising |
|
Botox injection |
Temporary |
|
Pyloroplasty |
Selected cases |
Feeding & Nutrition Support
|
Situation |
Strategy |
|
Severe malnutrition |
Jejunal feeding |
|
Intolerance to EN |
TPN (last resort) |