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What is
Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) or spastic colon is a symptom-based diagnosis that affects colon (large intestine). It is characterized by chronic abdominal pain, discomfort, bloating, and alteration of bowel habits. Diarrhea or constipation may predominate, or they may alternate.
It’s a functional gastrointestinal disorder, IBS has no known organic cause.
What happens In IBS:
The most common theory is that IBS is a disorder of the interaction between the brain and the gastrointestinal tract. While the cause of IBS is unknown, a disruption of the brain-gut axis and small intestinal bacterial overgrowth are thought to be important factors.
Classification
IBS can be classified as
- Diarrhea-predominant (IBS-D)
- Constipation-predominant (IBS-C)
- With alternating stool pattern (IBS-A)
- Pain-predominant.
- Postinfectious IBS (IBS-PI).(In some individuals, IBS may have an acute onset and develop after an infectious illness : fever, vomiting, diarrhoea, or positive stool culture).
Symptoms & Signs
- Abdominal Pain and Discomfort .Pain usually comes and goes. The length of each bout of pain can vary greatly. The pain often eases when you pass stools (faeces) or wind. Many people with IBS describe the pain as a spasm or colic.
- Bloating and distention of abdomen.( Flatulence)
- Changes in stools: Some people have bouts of diarrhoea, and some have bouts of constipation.Sometimes the stools become small and pellet-like. Sometimes the stools become watery or more loose. At times, mucus may be mixed with the stools.
- There may also be urgency for bowel movements, a feeling of incomplete evacuation( tenesmus)
- Associated complaints :People with IBS, more commonly than others, have gastroesophageal reflux, symptoms relating to the genitourinary system, chronic fatigue syndrome, fibromyalgia, headache, backache
- A strong association with psychiatric symptoms such as depression and anxiety. About a third of men and women who have IBS also report sexual dysfunction typically in the form of a reduction in libido.
What causes IBS
While the cause is unknown, there are frequent risk factors viz
- Post infection- after acute gastrointestinal infection, esp. a possible unrecognized protozoal infection such as blastocystosis as a cause of IBS.
- Young age
- Prolonged fever
- Psychological factors like Anxiety and Depression- The stress response in the body involves the HPA axis and the sympathetic nervous system, both of which have been shown to operate abnormally in IBS patients.
- Antibiotic usage
- Genetic influence– This factor does not follow classic Mendelian but is of the complex/multifactorial variety. 286 genes have been identified that are variably expressed in IBS-D patients
- Other theories: consumption of spicy food, changes in serotonin metabolism.
Changes in the Gut
There is evidence that abnormalities occur in the gut flora of individuals who suffer from IBS such a loss of diversity with a decrease in Bacteroidetes. The changes in gut flora are most profound in individuals who have diarrhoea predominant IBS. Antibodies against common components (namely flagellin) of the commensal gut flora are a common occurrence in IBS affected individuals. Chronic low-grade inflammation commonly occurs in IBS affected individuals with abnormalities found including increased enterochromaffin cells, intraepithelial lymphocytes, and mast cells resulting in chronic immune mediated inflammation of the gut mucosa.
Diagnosis
No specific laboratory or imaging test can be performed to diagnose irritable bowel syndrome. Diagnosis involves excluding conditions that produce IBS-like symptoms, and then following a procedure to categorize the patient’s symptoms. Ruling out parasitic infections, lactose intolerance, small intestinal bacterial overgrowth, and celiac disease is recommended for all patients before a diagnosis of irritable bowel syndrome is made. The Investigations performed are mentioned below:
- Stool microscopy and culture (to exclude infectious conditions)
- Blood tests: Full blood examination, liver function tests, erythrocyte sedimentation rate.
- Serological testing for coeliac disease
- Abdominal ultrasound (to exclude gallstones and other biliary tract diseases)
- Endoscopy and biopsies (to exclude peptic ulcer disease, coeliac disease, inflammatory bowel disease, and malignancies)
- Hydrogen breath testing (to exclude fructose and lactose malabsorption)
Management
A number of treatments have been found to be effective including: fiber, talk therapy antispasmodic and antidepressant medication, and peppermint oil.
- Diet: Some people with IBS have food intolerances. A low FODMAP diet has been shown to reduce symptoms in functional gastrointestinal disorders (such as IBS) by 60-80%. This diet restricts various carbohydrates which are poorly absorbed in the small intestine, as well as fructose( for fructose intolerance) and lactose( for lactose intolerance).
- FODMAPs diet: A diet restricted in fermentable oligo- di- and monosaccharides and polyols (FODMAPs) now has an evidence base sufficiently strong to recommend its widespread application in conditions such as IBS and IBD.
- Fiber: Some evidence suggests soluble fiber supplementation (e.g., psyllium/ispagula husk) is effective. It acts as a bulking agent, and for many IBS-D patients, allows for a more consistent stool. However, insoluble fiber (e.g., bran) has not been found to be effective for IBS.
- Probiotics
Medication
- Medications may consist of stool softeners and laxativesin IBS-C.( osmotic laxatives such as polyethylene glycol, sorbitol, and lactulose can help avoid “cathartic colon” which has been associated with stimulant laxatives.)
- Serotonin antagonistssuch as ondansetron are effective in postinfectious IBS and diarrhoea-dominant IBS due to their blockade of serotonin on 5HT3 receptors in the gut
- Atypical antipsychotic medications, such as clozapineand olanzapine,
- Selective serotonin reuptake inhibitor antidepressants
- Antispasmodics: The use of antispasmodic drugs (e.g., anticholinergics such as hyoscyamine or dicyclomine) may help patients, especially those with cramps or diarrhea
- Seratonin Agonists(Tegaserod (Zelnorm)).
- Rifaximin can be used as an effective treatment for abdominal bloating and flatulence
- Domperidone, a dopamine receptor blocker and a parasympathomimetic
- Antidiarrheals (e.g., opiate, opioid, or opioid analogs such as loperamide, codeine, diphenoxylate) in IBS-D.
Psychological therapies
The mind-body or brain-gut interactions has been proposed for IBS, and is gaining increasing research attention. Hypnosis can improve mental well-being, and cognitive behavioural therapy can provide psychological coping strategies for dealing with distressing symptoms.
Stress relief:
Reducing stress may reduce the frequency and severity of IBS symptoms. Techniques that may be helpful include:
- Relaxation techniques such as meditation
- Physical activities such as yoga or tai chi
- Regular exercise such as swimming, walking, or running.
The following case describes a young 22 year old female, a student diagnosed with IBS, who was unable to get relief elsewhere.