Irritable Bowel Syndrome

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Definition/Description

Irritable bowel syndrome (IBS) is a group of symptoms that represent the most common disorder of the GI system. IBS is a functional disorder of motility in the small and large intestine. IBS is also identified as nervous indigestion, functional dyspepsia, spastic colon, nervous colon, irritable colon, pylorospasm, spastic colitis, intestinal neuroses and laxative or cathartic colitis. Although IBS has been referred to as a type of colitis it is not an inflammatory disease of the intestinal tract (Goodman).

Prevalence

IBS is one of the most commonly diagnosed GI disorders in the U.S. with 20% of the population affected. In Western society it accounts for 50% of sub-specialty referrals (Goodman & Snyder). Women are more affected than men, especially in early adulthood, with a peak after the age of 50. However, IBS can occur in either gender at any age. Approximately 45 million Americans have been diagnosed with IBS, and it is likely more are affected but have yet to be diagnosed (Goodman & Fuller).

Characteristics/Clinical Presentation

GI symptoms are highly variable and can include but are not limited to nausea, vomiting, anorexia, foul breath, sour stomach, flatulence, cramps, abdominal bloating, and constipation and/or diarrhea. Some patients may report white mucus in their stool (Goodman & Snyder). Pain may be steady or intermittent, and there may be a dull, deep discomfort with sharp cramps in the morning or after eating. The typical pain pattern consists of lower left quadrant abdominal pain accompanied by constipation and diarrhea. Upper abdominal pain that extends up under the ribs can occur when the sigmoid colon in the left lower abdomen contracts and gas rises into the transverse colon. Abdominal discomfort and pain is relieved by defecation (Goodman & Fuller).  

Summary of clinical features in irritable bowel syndrome
Physical :
■■ Abdominal distension (clinical sign).
■■ Abdominal pain or discomfort
■■ Bloating.
■■ Diarrhoea, constipation or both.
■■ Lower abdominal pain, alleviated by bowel movement.
■■ Change in bowel habit (alternating constipation and diarrhoea) or
change in appearance of stools.
■■ Mucus in stools.
■■ A feeling of incomplete emptying of the bowels.
■■ A feeling of urgency.
■■ Fatigue, can be persistent.
■■ Irritable bladder (including urinary frequency and urgency).
■■ Back pain.
■■ Pain during intercourse (dyspareunia).
■■ Symptoms made worse by eating.
■■ Nausea.
■■ Headache.
■■ Belching and flatus.
■■ Poor appetite.
■■ Muscle pains.
■■ Immediate satiation after eating.
■■ Heartburn.
Mental :
■■ Anxiety.
■■ Depression.

• There is variation and overlap in symptoms for many patients and the list of symptoms cited are commonly experienced. It is by no means an indication of a typical IBS profile since many patients experience few or all of these symptoms (Shan, 2009).

Associated Co-morbidities

Extra-GI conditions associated with IBS are numerous, such as fibromyalgia, chronic fatigue syndrome, temporomandibular joint disorder, and chronic pelvic pain (Goodman & Fuller). IBS is also often linked with psychosocial factors. In cases where symptoms are severe and unchanged by treatment, a history of mental, physical or sexual abuse may be considered. IBS is commonly diagnosed in the early adulthood of females and there is a well documented association between IBS and dysmenorrhea. At this time it is not known whether this correlation is one of diagnostic confusion or whether dysmenorrhea and IBS have a common physiologic basis (Goodman & Snyder).  

Medications

At this time antianxiety/antidepressant drugs and anticholinergic agents are used before meals to help control symptoms. The enteric nervous system and the brain use the same chemicals and hormones. This fact may explain why low doses of antidepressants designed to affect the brain may improve certain digestive diseases. Antidepressants are thought to operate by reducing visceral hypersensitivity at the level of the visceral afferent fibers. Along this same line of thought, newer drugs being used in the treatment of IBS include serotonin-modulating agents that inhibit the action of serotonin in the gut. The GI tract contains an estimated 90-95% of the body’s serotonin. Serotonin is a neurotransmitter found in the brain and gut and appears to be a common link involved in GI motility, intestinal secretion, and pain perception. Research continues to search for targeted serotonin medications that can be individualized to each patient dependent upon their presentation and symptoms (Goodman & Fuller).

Other medications include probiotic treatment with Lactobacillus and Bifidobacterium which may help to alter the microbial flora of the intestinal tract and ease the symptoms of IBS. Alternative therapy, such as peppermint oil, chamomile, rosemary, valerian, ginger, and turmeric, has antispasmodic effects and may relieve cramping (Goodman & Fuller).

Recent Research- In a recent study by Saito et al., St. John’s Wart was tested in a randomized control trial to define it’s efficacy in the treatment of IBS. Due to the antidepressant affects of St. John’s Wart it was hypothesized St. John’s Wart may have a calming affect as other antidepressants have on IBS. However, it was found that St. John’s Wart was less effective then the placebo in a 12 week treatment of participants with an established diagnosis of IBS. 
 

Diagnostic Tests/Lab Tests/Lab Values

Diagnosis of IBS happens one of two ways, either by “diagnosis of exclusion” or the symptom based approach (William et al, 2005). Diagnosis of exclusion may involve one or more tests such as an ultrasound, thyroid function test, endoscopy (rigid/flexible sigmoidoscopy, colonoscopy, barium enema) to examine the colonic lumen for other possible pathology, complete blood count and stool examination to rule out lactose intolerance and the presence of occult blood, parasites and pathogenic bacteria (Shan, 2009). The symptom based approach uses developed criteria for the diagnosis of IBS (Goodman & Fuller).

Many symptom based criteria exist, which can make it hard to decide which criteria to use. One of the most common criteria used to date by physicians is the Roma II criteria. A positive diagnosis is determined if the patient answers yes to the question ‘Have you ever had continuous or repeated pain, cramping, or discomfort in your abdomen for at least 12 weeks (which need not be consecutive) in the past 12 months’? The patient must also select at least two of the following choices in response to the question: ‘In the past 12 months, which if any of the following have you experienced in combination with abdominal pain, cramping, or discomfort (select all that apply)’? (A) Relief from abdominal pain, cramping, or discomfort with a bowel movement; (B) more frequent bowel movements; (C) fewer bowel movements; (D) loose or watery stools; (E) firmer or harder stools; (F) none of the above. Patients that meet the criteria for IBS are then classified into IBS subtypes based on their responses to the second question. Diarrhoea-predominant patients are defined as those who report at least two of outcomes A, B and D, but not C or E. Constipation-predominant patients are defined as those who report at least two of outcomes A, C and E but not B or D. Those who report outcomes of B and/or D and C and/or E are defined as alternators or mixed IBS patients (Williams et al, 2005).

The symptom based approach for diagnosis of IBS is not fool proof. A practitioner must use good judgment and take into account any red flag symptoms like rectal bleeding, unintended or unexplained weight loss, onset of IBS symptoms over the age of 50, family history of bowel or ovarian cancer, abdominal or rectal masses, severe diarrhea, or raised inflammatory markers which may suggest inflammatory bowel disease as signs to proceed with more testing (Goodman & Snyder).  Symptom based approaches also vary widely and have yet to be standardized over any one health profession. Research is still being done to decide the reliability and validity of different symptom based criteria as well as their ability in ruling out other pathology and ruling in IBS as the correct diagnosis. For more information, one can review the articles attached below. 
 

Causes

IBS is considered a “functional” disorder because the symptoms cannot be attributed to any identifiable abnormality of the bowel, structural or biochemical. It is thought IBS may involve three main abnormalities of gut function: altered GI motor activity, visceral hypersensitivity, and/or altered processing of information by the nervous system. IBS is characterized by abnormal intestinal contractions theorized as a result of the digestive tract’s reaction to emotions, stress, and certain chemicals in particular foods. People with IBS have an exaggerated gastrocolic reflex, the signal the stomach sends to the colon to stimulate contractions after food arrives. Some cases IBS have no signs of increased GI motility, suggesting an increased internal sensitivity.
This enhanced sensation and perception of what is happening in the digestive tract referred to as “enhanced visceral nociception.” In such cases it may be that the internal pain threshold is lowered for reasons that remain unclear. Individuals with IBS experience pain and bloating at much lower pressures than people without IBS. Serotonin, a neurotransmitter produced in the gut and located inside the enteric nerve cells, may also play a role in the disorder. The GI tract is very sensitive to changes in serotonin levels. It’s possible IBS occurs as a result of abnormalities in serotonin levels responsible for digestive function. Increased levels of serotonin in the gut result in diarrhea, while decreased levels may account for individuals who have IBS-associated constipation.
It is well documented that individuals with IBS report a greater number of symptoms compatible with a history of psychopathologic disorders, abnormal personality traits, psychologic distress, and sexual abuse. Episodes of emotional or psychologic stress, fatigue, smoking, alcohol intake, or eating (expecially a large meal with high fat content, roughage, or fruit) do not cause but rather trigger symptoms. Intolerance of lactose and other sugars may account for IBS in some people. Scientists continue to explore the brain-gut connection to better understand IBS and other functional GI disorders. The enteric nervous system is composed of a vast network of neurons located throughout the GI tract. This neuronal network communicates directly with the brain through the spinal cord. There are as many neurons in the small intestine as in the spinal cord, and the same hormones and chemicals that transmit signals in the brain have been found in the gut, including serotonin, norepinephrine, nitric oxide, and acetylcholine. Studies investigating the effects of emotional words on the digestive tract substantiated the close interaction among mind, brain, and gut. Preliminary data demonstrate an increase in intestinal contractions and change in rectal tone during exposure to angry, sad, or anxious words. These changes of intestinal motor function may influence brain perception (Goodman & Fuller).

Systemic Involvement

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Medical Management (current best evidence)

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Physical Therapy Management (current best evidence)

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Alternative/Holistic Management (current best evidence)

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Differential Diagnosis

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Case Reports

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Resources

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Recent Related Research (from Pubmed)

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References

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