Chronic nausea and vomiting: new insights and approach to treatment

Chronic Unexplained Nausea and Vomiting or Gastric Neuromuscular Dysfunction (GND)? An Update on Nomenclature, Pathophysiology and Treatment, and Relationship to Gastroparesis

OPINION STATEMENT

Chronic unexplained nausea and vomiting is a debilitating condition that dramatically decreases patient quality of life and creates diagnostic and treatment challenges for healthcare providers. Additionally, the significant overlap in symptoms between disorders such as chronic unexplained nausea and vomiting, gastroparesis, and functional dyspepsia has resulted in a blurring of diagnostic lines and added confusion to the therapeutic approach. The identified overlap in clinical symptoms also suggests a common underlying pathophysiological mechanism may drive these conditions, indicating they could possibly be part of a spectrum of gastric neuromuscular disorders instead of discrete processes. This article will discuss the classification, updates in pathophysiology and therapeutic research, and future directions of research in the treatment of chronic unexplained nausea and vomiting.

What is nausea? A historical analysis of changing views

The connotation of "nausea" has changed across several millennia. The medical term 'nausea' is derived from the classical Greek terms ναυτια and ναυσια, which designated the signs and symptoms of seasickness. In classical texts, nausea referred to a wide range of perceptions and actions, including lethargy and disengagement, headache (migraine), and anorexia, with an awareness that vomiting was imminent only when the condition was severe. However, some recent articles have limited the definition to the sensations that immediately precede emesis. Defining nausea is complicated by the fact that it has many triggers, and can build-up slowly or rapidly, such that the prodromal signs and symptoms can vary. In particular, disengagement responses referred to as the "sopite syndrome" are typically present only when emetic stimuli are moderately provocative, and do not quickly culminate in vomiting or withdrawing from the triggering event. This review considers how the definition of "nausea" has evolved over time, and summarizes the physiological changes that occur prior to vomiting that may be indicative of nausea. Also described are differences in the perception of nausea, as well as the accompanying physiological responses, that occur with varying stimuli. This information is synthesized to provide an operational definition of nausea.

Chronic nausea and vomiting: insights into underlying mechanisms

Chronic nausea and vomiting are common and debilitating symptoms in adults. There are some fundamental problems that make our understanding of mechanisms difficult, diagnostic definitions of patient-cohorts being central. As there is no unifying mechanism with a direct link to chronic nausea or vomiting, it is most likely that several mechanisms interact, e.g., pylorus function and its relation to gastric emptying, or gastric sensory and motor function. In this mini-review, we highlight the roles and evidence for brain-gut interactions as well as gastrointestinal neurophysiologic, motor, sensory, and hormonal factors involved in the pathophysiology of chronic nausea and vomiting. There are factors not mentioned in the text, mostly as they are not well characterized in the setting of chronic symptoms or only in animal models.

Loss of Interstitial Cells of Cajal and Patterns of Gastric Dysrhythmia in Patients With Chronic Unexplained Nausea and Vomiting

BACKGROUND & AIMS

Chronic unexplained nausea and vomiting (CUNV) is a debilitating disease of unknown cause. Symptoms of CUNV substantially overlap with those of gastroparesis, therefore the diseases may share pathophysiologic features. We investigated this hypothesis by quantifying densities of interstitial cells of Cajal (ICCs) and mapping slow-wave abnormalities in patients with CUNV vs controls.

METHODS

Clinical data and gastric biopsy specimens were collected from 9 consecutive patients with at least 6 months of continuous symptoms of CUNV but normal gastric emptying who were treated at the University of Mississippi Medical Center, and from 9 controls (individuals free of gastrointestinal disease or diabetes). ICCs were counted and ultrastructural analyses were performed on tissue samples. Slow-wave propagation profiles were defined by high-resolution electrical mapping (256 electrodes; 36 cm(2)). Results from patients with CUNV were compared with those of controls as well as patients with gastroparesis who were studied previously by identical methods.

RESULTS

Patients with CUNV had fewer ICCs than controls (mean, 3.5 vs 5.6 bodies/field, respectively; P < .05), with mild ultrastructural abnormalities in the remaining ICCs. Slow-wave dysrhythmias were identified in all 9 subjects with CUNV vs only 1 of 9 controls. Dysrhythmias included abnormalities of initiation (stable ectopic pacemakers, unstable focal activities) and conduction (retrograde propagation, wavefront collisions, conduction blocks, and re-entry), operating across bradygastric, normal (range, 2.4-3.7 cycles/min), and tachygastric frequencies; dysrhythmias showed velocity anisotropy (mean, 3.3 mm/s longitudinal vs 7.6 mm/s circumferential; P < .01). ICCs were less depleted in patients with CUNV than in those with gastroparesis (mean, 3.5 vs 2.3 bodies/field, respectively; P < .05), but slow-wave dysrhythmias were similar between groups.

CONCLUSIONS

This study defined cellular and bioelectrical abnormalities in patients with CUNV, including the identification of slow-wave re-entry. Pathophysiologic features of CUNV were observed to be similar to those of gastroparesis, indicating that they could be spectra of the same disorder. These findings offer new insights into the pathogenesis of CUNV and may help to inform future treatments.

Characteristics of patients with chronic unexplained nausea and vomiting and normal gastric emptying

BACKGROUND & AIMS

Chronic nausea and vomiting with normal gastric emptying is a poorly understood syndrome; we analyzed its characteristics.

METHODS

We collected and analyzed data from 425 patients with chronic nausea and vomiting, enrolled at 6 centers by the Gastroparesis Clinical Research Consortium in the National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Registry.

RESULTS

Among the patients, 319 (75%) had delayed emptying, defined by the results of a standardized, low-fat meal, and 106 had normal gastric emptying. Patients with or without delayed emptying did not differ in age, sex, or race, although those with normal gastric emptying were less likely to be diabetic. Symptom severity indexes were similar between groups for nausea, retching, vomiting, stomach fullness, inability to complete a meal, feeling excessively full after meals, loss of appetite, bloating, and visibly larger stomach. There were no differences in health care utilization, quality of life indexes, depression, or trait anxiety scores. However, state anxiety scores were slightly higher among patients with delayed gastric emptying. Total gastroparesis cardinal symptom index scores were not correlated with gastric retention after 2 or 4 hours in either group. Patients with the syndrome were not adequately captured by the stand-alone criteria for the Rome III diagnoses of chronic idiopathic nausea and functional vomiting. With rare exceptions, the diagnosis remained stable after a 48-week follow-up period.

CONCLUSIONS

Patients with nausea and vomiting with normal gastric emptying represent a significant medical problem and are, for the most part, indistinguishable from those with gastroparesis. This syndrome is not categorized in the medical literature--it might be a separate clinical entity.

Pathophysiological and psychosocial study in patients with functional vomiting

Background/Aims

To explore clinical patterns, predisposing factors, psychosocial aspects and the possible pathogenesis in Functional Vomiting (FV) patients.

Methods

Ten healthy subjects and 19 FV patients participated in this study. Gastrointestinal symptoms and psychological state were evaluated by questionnaires, including Zung self-rating anxiety and depression scale and Eysenck personality questionnaire. Cutaneous electrogastrography, perfusion nutrition load test and intragastric pressure were performed in patients. Perfusion nutrition load test and intragastric pressure were also performed in healthy subjects.

Results

FV involved young female predominantly (4 male, 15 female; age 25.8 ± 8.4 years). Postprandial vomiting soon after meal without self-induced maneuver was the most common pattern of FV. Prevalence for overlaps between FV and functional dyspepsia was high (84.2%). Emotional changes and stress contributed to the development of FV. Prevalence of abnormal psychological status and personality in patients with FV was high (83.3% and 47.1%). Patients with FV had significant postprandial gastric dysrhythmia, impaired gastric accommodation and enhanced gastric sensitivity. There were significant correlations between clinical presentations, gastric function and psychological states.

Conclusions

Patients with FV had abnormal psychological status, gastric dysmotility and hypersensitivity, which indicated that both of peripheral and central abnormalities could contribute to the pathogenesis of FV.