What is gastric electrical stimulation for treating gastroparesis?

Gastric Electrical Stimulation for Gastroparesis

Gastric electrical stimulation (GES) is an FDA-approved surgical intervention for treating refractory gastroparesis that significantly improves nausea and vomiting symptoms in patients who have failed standard medical therapy, though it does not accelerate gastric emptying. 1

What is Gastric Electrical Stimulation?

Gastric electrical stimulation (Enterra Therapy) is a surgical treatment that involves:

• Implantation of a neurostimulator device that delivers high-frequency (12 cycles per minute), low-energy electrical stimuli to the stomach
• Placement of electrodes typically on the greater curvature of the stomach
• FDA approval since 2000 for treating drug-refractory gastroparesis symptoms 1

Mechanism of Action

The precise mechanism of action remains incompletely understood, but GES likely works through:

• Modulation of the gastric pacemaker system
• Influencing interstitial cells of Cajal function
• Activation of vagal afferent pathways that affect central control mechanisms for nausea and vomiting
• Possible alteration of sensory afferents or myoneural pathways
• Potential influence on gut peptide release 1, 2

Importantly, GES does not accelerate gastric emptying in most patients, suggesting its therapeutic benefit comes primarily through neural modulation rather than improved gastric motility. 1

Patient Selection Criteria

GES is specifically indicated for:

• Patients with medically refractory gastroparesis who have failed standard therapy
• Those with predominant symptoms of nausea and vomiting (not abdominal pain)
• Patients who are not dependent on opioid medications
• Primarily those with diabetic or idiopathic gastroparesis 1, 3

Contraindications and negative predictors:

• Predominant abdominal pain as the main symptom
• Current opioid use
• Very prolonged, intractable symptoms 1, 2

Clinical Effectiveness

The evidence for GES effectiveness shows:

• Significant improvement in refractory nausea and vomiting symptoms
• Enhanced quality of life
• Improved nutritional status
• Reduced hospitalizations and medication use
• Better glycemic control in diabetic patients 1, 4, 5

However, it's important to note that while unblinded studies consistently show benefit, randomized controlled trials have shown conflicting results. 6, 2

Temporary Stimulation

Temporary electrical stimulation may be used before permanent implantation to:

• Predict response to permanent GES
• Identify patients most likely to benefit
• Avoid unnecessary surgical procedures in non-responders 1

This approach should be offered when available, though more research is needed to fully validate this strategy. 1

Surgical Procedure and Considerations

The GES device is implanted through:

• Laparoscopic or open surgical approach
• Placement of stimulation leads on the greater curvature of the stomach
• Subcutaneous implantation of the neurostimulator device
• Programming of stimulation parameters post-implantation 5

The procedure has a relatively low complication rate compared to other surgical interventions for gastroparesis. 5

Alternative Interventions for Refractory Gastroparesis

For context, other options for refractory gastroparesis include:

• Pylorus-directed therapies like G-POEM (gastric peroral endoscopic myotomy) for patients with severe gastric emptying delay 1
• Intrapyloric botulinum toxin injection (though evidence is limited) 1
• Feeding jejunostomy tubes for nutritional support in severe cases 3

Common Pitfalls and Considerations

• GES is not effective for abdominal pain predominant gastroparesis
• Patients should be weaned off opioids before considering GES
• Temporary stimulation should be used when available to predict response
• Realistic expectations should be set - GES improves symptoms but does not cure gastroparesis
• Regular follow-up is needed to monitor device function and symptom control 1, 3

Outcomes and Prognosis

Long-term outcomes with GES show:

• Sustained symptom improvement in 75-97% of patients
• Potential for weight gain (average 5.5% at one year)
• Possible discontinuation of enteral/parenteral nutrition in previously dependent patients
• Improved quality of life 4, 5

GES represents an important therapeutic option for carefully selected patients with refractory gastroparesis when medical management has failed and nausea and vomiting are the predominant symptoms.