Gastroparesis is defined as a delay in gastric emptying in the absence of mechanical obstruction of the gastric outlet. Over the last decade, there has been a paradigm shift in our understanding of the clinical presentation & management of gastroparesis.

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In the absence of a physical blockage of the gastric outlet, gastroparesis causes food to sit in the stomach for an abnormally long period of time. To diagnose gastroparesis, it is necessary to observe an objective delay in stomach emptying in addition to the presence of symptoms including nausea, vomiting, and postprandial abdominal fullness. Delayed stomach emptying characterises gastroparesis (GP), a disease that may be difficult to diagnose for many doctors. Most people sent to a GP are instead diagnosed with functional dyspepsia (FD). Functional dyspepsia may cause vomiting, although the sickness is typically short-lived and moderate. When compared to gastroparesis, when nausea and vomiting are common, this is a notable difference.

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Mechanisms of gastroparesis

The vagus nerve in the stomach normally regulates muscular contractility and food movement into the small intestine. This nerve is considered to be affected in people with gastroparesis, resulting in impaired signalling of stomach muscles, resulting in a slower emptying time and perhaps improper digestion.

This condition may have an idiopathic aetiology, but it is frequently observed in patients with diabetes, neurologic or smooth muscle disorders, anorexia or bulimia, gastroesophageal reflux disease (GERD), infections, endocrine disorders, autoimmune diseases, cancers, upper gastrointestinal (GI) surgery. Additionally, several drugs have been linked to delayed stomach emptying and decreased intestinal contractility.

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Aetiology

1. There are several gastroparesis causes. Approximately one-third of cases of gastroparesis is associated with diabetes mellitus type 1 or 2. One-third of cases are associated with a variety of causes, including post-surgical conditions, neurological disorders, metabolic and systemic disorders (SLE, systemic sclerosis, amyloidosis, hypothyroidism, HIV), and inflammatory disorders of the gastrointestinal tract.
2. The remaining one-third of cases are idiopathic.

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Prevalence

• The real incidence of gastroparesis is unclear.
• It is estimated that up to 4% of the general population suffers gastroparesis symptoms.
• In diabetes mellitus, 5-12% of patients present with symptoms of delayed stomach emptying.
• 30-50% of diabetics, as objectively confirmed by a gastric emptying test, have delayed stomach emptying.
• 24-40% of individuals with functional dyspepsia have delayed stomach emptying.
• 82% of patients in a significant study on the long-term results of people with gastroparesis were female.

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Clinical features

1. Idiopathic gastroparesis symptoms overlap with those of functional dyspepsia or recurrent vomiting many hours after eating and are strongly indicative of gastroparesis or nausea, vomiting, and postprandial fullness are upper gastrointestinal symptoms linked with gastroparesis.
2. Stomach discomfort and pain prevail in functional dyspepsia, while nausea, vomiting, bloating, postprandial fullness, and early satiety predominate in idiopathic gastroparesis.

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How to diagnose the condition 

A comprehensive medical history and physical examination are required for patients who exhibit clinical gastroparesis symptoms. In addition, a range of diagnostic techniques, like scintigraphy, radiography, breath testing, and antroduodenal manometry, may be utilised to accurately identify this illness.

The diagnosis of gastroparesis is based on the existence of symptoms or characteristic indicators together with objective evidence of a delay in stomach emptying. Ideally, gastrointestinal endoscopy should be used to rule out mechanical outlet blockage and other (extra-luminal) pathologies. The presence of residual food in the stomach after overnight fasting or the presence of a bezoar during endoscopy strongly suggests delayed gastric emptying.

The diagnostic gold standard for gastroparesis is solid-food gastric emptying scintigraphy. This test is conducted up to 4 hours after the intake of a radiolabeled meal to identify delayed gastric emptying by evaluating the number of stomach contents and the relaxation of the stomach.

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Management

In order to design a suitable treatment strategy for gastroparesis, physicians must first identify the severity of the symptoms. Moderate to severe gastroparesis symptoms may need medication in addition to dietary and lifestyle changes. In resistant individuals, gastric failure may ensue, necessitating the aforementioned procedures as well as PEG tube insertion, parenteral nourishment, or stomach electrical stimulation.

The therapy of gastroparesis should always focus on three primary objectives:

1. Symptom reduction or prevention.
2. Correction or prevention of dietary, fluid, and electrolyte imbalances.
3. Diagnosis and treatment of underlying causes.

When diagnosing an adult patient with irregular blood glucose control or unexplained stomach bloating or vomiting, clinicians should take into account the possibility of gastroparesis while also considering other probable illnesses.

If an adult has gastroparesis, consider trying metoclopramide, domperidone, or erythromycin. If gastroparesis is suspected, consider seeking specialist assistance if the differential diagnosis is unclear, or persistent or severe vomiting develops.

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Diet and lifestyle 

Dietary strategies are essential for the treatment of gastroparesis.

1. Reduce the consumption of fatty foods.
2. Consume smaller portions more frequently throughout the day.
3. Maintain an upright position during and after a meal.
4. Limit the consumption of insoluble fibres.
5. Quit smoking, although it should be noted that smoking itself triggers the gastro colonic reflex and accelerates intestinal transit.
6. Check for deficiency, particularly in individuals with weight loss and malnutrition, and employ multivitamins and/or vitamin supplementation if necessary.
7. In situations of significant weight loss or insufficient food intake, nasoduodenal enteral feeding should be explored.

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Prokinetics

Metoclopramide and domperidone

1. A dopamine D2 receptor antagonist, metoclopramide has both antiemetic and prokinetic effects.
2. The antiemetic action of metoclopramide relies on the blockage of dopamine D2 receptors in the region postrema, which is situated outside the blood-brain barrier, and the vomiting centre.
3. Metoclopramide's prokinetic action relies on the inhibition of dopamine D2 receptors in the gastrointestinal system. It is known that dopamine inhibits the motility of the whole gastrointestinal system. It lowers stomach tone, intragastric pressure, and antroduodenal coordination by activating dopamine D2 receptors metoclopramide not only has dopamine D2 receptor antagonist qualities, but also mild 5-hydroxytryptamine-4 (5HT4) agonist and 5HT3 antagonist capabilities.
4. Domperidone is likewise a dopamine D2 receptor antagonist, and has comparable effects to metoclopramide but does not penetrate the blood-brain barrier, resulting in a significantly less antiemetic effect.

Erythromycin

1. A macrolide antibiotic that acts as a motilin receptor agonist promotes stomach emptying, antral contractions, and antroduodenal coordination, but decreases fundic volume and compliance in health and sickness.
2. In individuals with gastroparesis, oral administration of erythromycin is the preferable method for long-term usage. The liquid form of erythromycin may be advantageous in gastroparesis since it does not need disintegration in the stomach; nevertheless, its antibacterial activity, bacterial resistance, and the incidence of desensitisation to the therapeutic prokinetic effect restrict its long-term usage.

Other therapies

In addition to these medications, additional medical professionals may recommend an intrapyloric botulinum toxin injection, gastric pacing, or even more extreme surgical treatments like partial or complete gastrectomy.

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ACG guideline highlights include

1. Scintigraphic gastric emptying is the standard diagnostic test for gastroparesis among patients with upper gastrointestinal symptoms, according to the amended guideline. Evaluation of stomach emptying over 3 hours or longer after a substantial meal is one testing approach that is suggested.
2. A small particle diet should be a component of the dietary therapy of gastroparesis patients in order to improve the chance of symptom alleviation and stomach emptying.
3. Pharmacologic therapy should be taken into account when treating individuals with idiopathic or diabetic gastroparesis, taking into account both the advantages and disadvantages of the proposed course of action.
4. Metoclopramide therapy is recommended over no therapy for managing refractory symptoms in gastroparesis patients, and 5-HT4 agonist therapy is recommended over no therapy for enhancing stomach emptying. If licensed, domperidone is recommended for gastroparesis patients' symptom treatment.
5. Patients with symptoms resistant to medicinal therapy are advised to consider pyloromyotomy as an alternative to no treatment for symptom management.

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Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

About the author of this article: Dr Monish Raut is a practising super specialist from New Delhi.