2. Definition
Irritable bowel syndrome (IBS) is a functional
bowel disorder in which abdominal pain or
discomfort is associated with defecation or a
change in bowel habit.
Bloating, distension, and disordered defecation are
commonly associated features.
WGO Practice Guidelines 2009
4. Epidemiology
• Mainly occurs between the ages of 15 and 65
• First presentation to physician - 30–50 yrs
• Prevalence is greater in women (except in India)
• Prevalence in children is similar to that in adults
5. IBS demographics
Studies in non-Western countries
• Lack of female predominance
• Greater frequency of upper abdominal pain
• Lower impact of defecatory symptoms on a
patient’s daily life
• Stool frequency - greater in the India as a
whole(99% )
6. IBS demographics
• Clinical overlap between functional dyspepsia and
IBS- very common in China
• In Latin America- constipation predominance is
more frequent than diarrhea predominance
11. • No consensus on the exact patterns of motor
derangement that induce constipation or
diarrhea.
• Motor abnormalities observed in IBS
??? Secondary than primary
12. VISCERAL HYPERSENSITIVITY :
• Balloon distension of rectum (1970)
• Found in 60% patients
• IBS pts more aware of intestinal gas/contractions
• Abnormal sensitization within the dorsal horn of
the spinal cord or higher up in the central nervous
system.
13. • Neurotransmitters - serotonin, neurokinins,
calcitonin gene-related peptide
• Capsaicin (redpepper) receptor on nerve fibers
increased in the rectosigmoid colon in IBS -
mediate visceral pain
• N-methyl-d-aspartate (NMDA) receptor
modulates central (spinal cord) neuronal
excitability
14. • Significant increase in serine proteases in
the stools of patients with IBS-D
• Serine proteases ?? damage tight
junctions increase intestinal permeability
• Inflammation is responsible for the
sensitization
15. ABNORMAL GAS PROPULSION AND
EXPULSION
• Retention of gas following gas infusion into the
small intestine is greater in patients with IBS
• Intestinal gas infusion - more discomfort than
controls
• ??? Involuntary suppression of abd.wall muscle
contraction during gas infusion more distension
• ??? SIBO contribute to bloating…..uncertain
16. LOCAL INFLAMMATION
• Increased mast cells and activated T- lymphocytes above
normal in the mucosa in patients with IBS
• Lymphocytic infiltration of the myenteric plexus with
neuron degeneration - in severe IBS
• Recovery from a proved episode of bacterial enteritis in 7-
30% patients
( illness lasting > 3wks or caused by toxigenic
organisms)
• A central role of mast cells ??? abd.pain
18. ROLE OF FOOD
• Wheat, dairy products, citrus fruits, potatoes, onions, and
chocolate
• 50% patients showed symptomatic improvement on
elimination of pptating diets – uncontrolled trial
• ?? Subtle forms of gluten intolerance in IBS-D patients
( symptomatic improvement in 70% IBS-D patients with
positive HLA-DQ2 status with gluten restricted diet)
19. • Fructose & sorbitol
malabsorption contributes
to IBS ??
( no difference from
controls on double blinded
trial)
20. ABNORMAL COLONIC FLORA AND SMALL
INTESTINAL BACTERIAL OVERGROWTH
• Increased colonic fermentation, production of excess gas
symptoms ?? Role of probiotics
• High prevalance of SIBO in IBS
(based on H2 breath tests & clinical response to non-
absorbable antobiotics)
21. CENTRAL DYSREGULATION
• Alterations in the brain response to visceral stimuli in IBS
( functional MRI & PET)
• Greater activation of the mid-cingular cortex following
delivered or anticipated rectal distention
(explains why anxiety or stress can enhance perception of
visceral pain, whereas relaxation or distraction decreases
pain in IBS)
22. PSYCHOLOGICAL FACTORS
• Depression, anxiety, and somatization are the most
common coexistants in IBS (40% to 94% of patients)
• H/O sexual, physical, or emotional abuse - more often
( abuse ?? Alters brain response to visceral pain)
• Childhood stress – gastric suction– 3times more risk
• Anxiety secondary to intestinal inflammation (?TNF-alfa)
23. GENETIC FACTORS
• Familial clustering
• Greater concordance in monozygotic twins
• Potential genes :
a) lower expression of IL-10 gene
b) sodium channel mutation (SCN5)
c) serotonin type III receptor gene – functional varient
24. Clinical features
Symptoms
• Bloating
• Abnormal stool form (hard
and/or loose)
• Abnormal stool frequency (less
than three times per week or
over three times per day)
• Straining at defecation
• Urgency
• Feeling of incomplete
evacuation
• The passage of mucus per
rectum
25. Behavioral features
• Symptoms present for > 6 months
• Stress aggravates symptoms
• Frequent consultations for nongastrointestinal symptoms
• History of previous medically unexplained symptoms
• Aggravation after meals
• Associated anxiety and/or depression
27. Non-GI symptoms
• Lethargy
• Backache and other muscle and joint pains
• Headache
• Urinary symptoms: — Nocturia — Frequency and
urgency of micturition — Incomplete bladder emptying
• Dyspareunia, in women
• Insomnia
• Low tolerance to medication
28. Alarming features
History
• Blood in the stool
• Family H/O colon
cancer, IBD, celiac disease
• Fever
• Onset after age 50 years
• Nocturnal symptoms (awakening
the patient from sleep)
• Chronic diarrhea
• Progressive dysphagia
• Recurrent vomiting
• Severe chronic constipation
• Short history of symptoms
• Travel history to locations endemic
for parasitic diseases
• Weight loss
29. Alarming features
Physical Examination
• Abdominal mass
• Arthritis (active)
• Dermatitis herpetiformis or
pyoderma gangrenosum
• Occult or overt blood on rectal
examination
• Signs of anemia
• Signs of intestinal obstruction
• Signs of intestinal
malabsorption
• Signs of thyroid dysfunction
30. Diagnosis
• Based on history & clinical examination
• Matching patient’s profile to clinical criteria
45. Antidepressants and Anxiolytics
Tricyclic antidepressants(TCAs) - might improve global
well-being more than symptoms
• Start at a low dose (e.g., 10 to 25 mg of desipramine or
nortriptyline) and increase the dose by 10 to 25 mg
weekly, aiming for a dose of 75 mg initially
• Most beneficial in IBS-D
Selective serotonin reuptake inhibitors (SSRIs)
• Fewer side effects
• More beneficial in IBS-C
WGO practice guidelines 2009
51. Management
STEP SEVERITY LEVEL OF
CARE
MANAGEMENT
1 Mild Primary Diagnosis,explanat
ion,reassurance,
follow-up
2 Moderate Secondary Reinforce step 1
3 Severe Tertiary Avoid over-
testing,add
TCA/SSRI,
alosetron for
severe
diarrhea;treat
anxiety/depression
;refer to pain clinic
52. Choice of treatment
Predominant symptom First step Second step
Bloating Adjust, Treat constipation Probiotic,antibiotic,TCA,
SSRIs
Constipation Fibre supple./ Poly
ethylene glycol
Lubiprostone
Diarrhea Loperamaide Alosetron
Abdominal pain Antispasmodic,peppermin
t oil
TCAs,SSRIs,
Psychotherapy
53. What’s new ???
IBS-C
• 5-HT4 receptor agonists-
Tegaserod (withdrawn d/t cardiac events)
Prucalopride,Naronapride,Velusetrag
(no cardiac risk & more efficacy in early studies)
• Guanylate cyclase C agonists
Linaclotide -Chey et al(2012)- 46% pts improved
approved for use in the USA by the FDA in August
2012 for adults
54. Adsorbents
• AST 120, a carbon-based adsorbent
(absorption of histamine, serotonin, bacterial products and
bile acids )
32% pts improved in priliminary studies
5-HT3 receptor antagonist – Ramosetron
( RC trial – 343 patients, no significant benefit)
58. Prognosis
• Relapses are common
• 9-10% develop organic disease a median of 15
years after diagnosis
• Poor prognosis
excessive psychological distress
anxiety, long duration of complaints
59. Take Home Message
• No more a vague symptom complex
• Pathophysiology ???
• History & examination is of prime importance
• Always R/O organic disease before diagnosis
• Treatment – predominantly symptomatic
• Behavioral therapy is important
• Newer drugs in pipeline
