Irritable Bowel Syndrome

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Irritable Bowel Syndrome

• Rahul Gladwin, MS3
• University of Health Sciences Antigua
• School of Medicine
• Email rahulATrahulgladwin.com

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Definition Stats

• Characterized by irregular bowel habits and
  abdominal pain without any structural
  abnormalities.
• Throughout the world, 10-20 of people might have
  IBS
• More common in women
• Compare with inflammatory bowel disease.

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Associations

• Symptoms usually overlap with other disorders
  such as fibromyalgia, backache, headache, and
  genitourinary symptoms.
• Other affecting factors include altered
  gastrointestinal GI motility, visceral
  sensitivity, abnormal central processing,
  disturbance of brain-gut interaction, genetic and
  environmental factors, autonomic and hormonal
  events, and psychosocial disturbances.

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Clinical

• Usually affects individuals younger than 45.
• Decreased incidence in older individuals
• Women are 2-3 times more likely to have IBS. 80
  patients are women

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Findings

• The main finding is abdominal pain during morning
  hours which may be in the hypogastrium (25),
  right (20), left (20), and epigastrium (10).
• Other findings may include defecation straining,
  urgency or a feeling of incomplete bowel
  movement, bloating, and passing mucus.

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DIAGNOSTIC CRITERIA (from Harrisons)
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Pathophysiology

• Poorly understood.
• May be due to abnormal gut motor and sensory
  activity, central neural dysfunction, stress, and
  psychological disturbances.
• Studies of motor and colonic myoelectrical
  activity under unstimulated conditions are normal.

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Pathophysiology

• There is increased rectosigmoid activity 3 h
  after eating.
• Stimulation with rectal balloon (Flexi-Seal) of
  diarrhea-prone patients showed distention-evoked
  contractile activity.
• IBS patients show exaggerated sensory responses
  to visceral stimulation suggesting visceral
  afferent dysfunction..

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Pathophysiology

• Lipids exaggerate sensation of gas, discomfort,
  and pain in IBS patients.
• There is a correlation between stress and
  emotional disorders and IBS.
• IBS patients have increased activity in the
  mid-cingulate cortex associated with visceral
  pain, response selection and attention process.
• Study done in January 2011 shows that small
  intestine bacterial overgrowth (SIBO) may play a
  role in IBS.

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Pathophysiology

• Gastroenteritis may predispose IBS in 25 of
  patients - Campylobacter, Salmonella, and
  Shigella most likely involved.
• IBS patients more likely to have increased
  serotonin (5HT)-containing enterochromaffin cells
  in the colon.
• Serotonin plays an important role in visceral
  perception and regulation of GI motility

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Differentials

• Lactase deficiency.
• Celiac sprue.
• Side-effects from anticholinergic,
  antihypertensive, and antidepressant medications.
• Biliary tract disease, intestinal ischemia,
  peptic ulcer disorders, and carcinoma of the
  stomach and pancreas.
• Diverticular disease of the colon, inflammatory
  bowel disease
• Giardia
• Laxative abuse
• Hyperthyroidism

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Treatments
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Treatments

• High-fiber diets.
• Anticholinergic drugs inhibit gastrocolic reflex
  (ipratropium bromide).
• Anti-diarrheals (loperamide).
• Anti-depressants TCAs and SSRIs (fluoxetine).
• Activated charcoal as part of anti-flatulence
  therapy.
• Serotonin Receptor Agonist and Antagonists
  alosetron, tegaserod.
• Chloride Channel Activators lubiprostone.

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Sources

• Harrisons Internal Medicine 17th edition.
• www.medpagetoday.com
• www.ncbi.nlm.nih.gov