Introduction

Irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional condition of the gastrointestinal system characterised by abdominal discomfort that is accompanied by a change in the shape or frequency of faeces. 

^{(Photo Credit: commons.wikimedia.org)}

The most prominent risk factor is acute enteric infection, however, irritable bowel syndrome is also more prevalent in individuals with psychosocial comorbidities and young adult women compared to the general population. 

The underlying mechanisms of irritable bowel syndrome are not fully understood, although it is well-recognised that there is a disrupted 

communication between the digestive system and the brain. This disruption results in abnormal movement of the intestines, heightened sensitivity to internal organ sensations, and changes in how the central nervous system processes information. 

Additional pathways that are not easily replicated may involve genetic correlations, changes in gut microbiota, and disruptions in mucosal and immunological function. 

For the majority of individuals, diagnosis can typically be determined by considering their medical background and using investigations sparingly and carefully. However, if there are any concerning signs, like weight loss or rectal bleeding, or if there is a family history of inflammatory bowel disease or coeliac disease, further investigations may be necessary. After the diagnosis is determined, employing an empathic approach is crucial, as it can enhance the individual's quality of life, alleviate symptoms, and decrease healthcare costs. 

The primary components of treatment include providing patients with information on their disease, implementing modifications to their diet, including soluble fibre in their diet, and administering antispasmodic medications. Additional therapies are typically reserved for individuals experiencing severe symptoms. These treatments may involve the use of central neuromodulators, intestinal secretagogues, drugs that target opioid or 5-HT receptors, or minimally absorbed antibiotics. The specific treatment is chosen based on the predominant bowel habit of the individual. Psychological therapies may also be employed as part of the treatment plan.¹

Prevalence of IBS

The prevalence rates of Irritable Bowel Syndrome (IBS) range from 1.1% to 45%, as reported by population surveys conducted in different countries. The combined global prevalence of IBS is estimated to be 11.2%. Most European nations, the United States, and China claim prevalence rates ranging from 5% to 10%. The population statistics for Irritable Bowel Syndrome (IBS) in most African and many Asian countries are not available. This could be due to the difficulty in distinguishing between infectious diarrhoea and IBS in tropical countries, particularly in nations with inadequate healthcare systems or limited patient access to medical care. Additionally, there may be less focus on functional disorders by the healthcare system once an acute infection has been ruled out.²

Obtaining prevalence data for certain subtypes is a complicated task. There is a significant overlap in symptoms across different subtypes of IBS, and patients often experience changes in their major symptoms over time, leading them to transition between categories. Available population studies that have distinguished between distinct subtypes of irritable bowel syndrome (IBS) indicate that in countries where the overall incidence of IBS is around 10%, one-third of the affected population is diagnosed with IBS-C and another one-third with IBS-D. Most nations do not disclose the incidence rates of Irritable Bowel Syndrome (IBS), which refers to the yearly occurrence of new cases. However, a small number of long-term surveys (lasting 10 years or more) conducted in the United States provide an estimate of the annual incidence rate, which falls within the range of 1-2%. Simultaneously, there have been reports of disappearance rates of 2%, suggesting the occurrence of spontaneous illness remission.²

Nausea

Nausea and vomiting (N/V) are prevalent symptoms frequently seen in the field of medicine. Although managing most cases of acute nausea and vomiting (N/V) caused by a specific reason is usually uncomplicated, there are certain cases, such as chemotherapy-induced nausea and vomiting (CINV) and particularly chronic unexplained nausea and vomiting (CUNV), that can be challenging to control. These cases can result in a significant decrease in the patient's quality of life and an increase in medical expenses due to frequent hospitalisations.³

Nausea and vomiting can be caused by various factors. These include: (i) the presence of toxins, drugs, bacteria, viruses, or fungi in the gastrointestinal tract, which indirectly stimulate the brainstem emetic nuclei located in the dorsal vagal complex in the medulla oblongata.

Toxins, drugs and bacteria in the GI tract stimulate the brain stem to release neurotransmitters that activate the vagus nerves, causing nausea and vomiting response. (Photo Credit: istockphoto.com)

This stimulation occurs through the release of local emetic neurotransmitters in the upper gastrointestinal tract, activating receptors on vagus nerves and/or splanchnic nerves; (ii) toxic substances, drugs, or infectious organisms that enter the body and directly affect the emetic nuclei in the brainstem; (iii) abnormalities in the gastrointestinal tract that stimulate vagal afferents or other visceral organs, such as the heart, which in turn stimulate visceral afferents; (iv) emotional and cognitive stimuli within the central nervous system, including the cerebral cortex and the limbic system; and (v) disruptions in the vestibular nuclei and cerebellum, which can lead to motion sickness. Nausea and vomiting occur due to ongoing interactions among the gastrointestinal tract, including the enteric neural system, the central nervous system (CNS), and the autonomic nervous system.⁴