Introduction
Patients presenting with the symptoms of gastroparesis (Gp) are commonly seen in gastroenterology practice.
Presentation
Patients with foregut symptoms of Gp have characteristic presentations, with nausea, vomiting/retching, and abdominal pain often associated with bloating and distension, early satiety, anorexia, and heartburn. Mid- and hindgut gastrointestinal and/or urinary symptoms may be seen in patients with Gp as well.
The precise epidemiology of gastroparesis syndromes (GpS) is unknown. Classic gastroparesis, defined as delayed gastric emptying without known mechanical obstruction, has a prevalence of about 10 per 100,000 population in men and 30 per 100,000 in women with women being affected 3 to 4 times more than men.1,2 Some risk factors for GpS, such as diabetes mellitus (DM) in up to 5% of patients with Type 1 DM, are known.3 Caucasians have the highest prevalence of GpS, followed by African Americans.4,5
Dr. Prateek Mathur
The classic definition of Gp has blurred with the realization that patients may have symptoms of Gp without delayed solid gastric emptying. Some patients have been described as having chronic unexplained nausea and vomiting or gastroparesis like syndrome.6 More recently the NIH Gastroparesis Consortium has proposed that disorders like functional dyspepsia may be a spectrum of the two disorders and classic Gp.7 Using this broadened definition, the number of patients with Gp symptoms is much greater, found in 10% or more of the U.S. population.8 For this discussion, GpS is used to encompass this spectrum of disorders.
The etiology of GpS is often unknown for a given patient, but clues to etiology exist in what is known about pathophysiology. Types of Gp are described as being idiopathic, diabetic, or postsurgical, each of which may have varying pathophysiology. Many patients with mild-to-moderate GpS symptoms are effectively treated with out-patient therapies; other patients may be refractory to available treatments. Refractory GpS patients have a high burden of illness affecting them, their families, providers, hospitals, and payers.
Pathophysiology
Specific types of gastroparesis syndromes have variable pathophysiology (Figure 1). In some cases, like GpS associated with DM, pathophysiology is partially related to diabetic autonomic dysfunction. GpS are multifactorial, however, and rather than focusing on subtypes, this discussion focuses on shared pathophysiology. Understanding pathophysiology is key to determining treatment options and potential future targets for therapy.
Fig. 1: Pathophysiology of gastroparesis syndromes is illustrated.
Intragastric mechanical dysfunction, both proximal (fundic relaxation and accommodation and/or lack of fundic contractility) and distal stomach (antral hypomotility) may be involved. Additionally, intragastric electrical disturbances in frequency, amplitude, and propagation of gastric electrical waves can be seen with low/high resolution gastric mapping.
Both gastroesophageal and gastropyloric sphincter dysfunction may be seen. Esophageal dysfunction is frequently seen but is not always categorized in GpS. Pyloric dysfunction is increasingly a focus of both diagnosis and therapy. GI anatomic abnormalities can be identified with gastric biopsies of full thickness muscle and mucosa. CD117/interstitial cells of Cajal, neural fibers, inflammatory and other cells can be evaluated by light microscopy, electron microscopy, and special staining techniques.
