INTERNAL MEDICINE

Irritable Bowel Syndrome EXEMIUS

DR. CHRISTINE B. SUBIA December 2019 2021
IRRITABLE BOWEL SYNDROME  If predominant symptom is constipation may have weeks or
 Functional bowel disorder characterized by abdominal pain or months of constipation interrupted with brief periods of
discomfort and altered bowel habits in the absence of diarrhea.
detectable structural abnormalities.  Diarrhea from IBS consists of small volumes of loose
 No clear diagnostic markers stools( <200 mL).
 10–20% of adults and adolescents have symptoms consistent  Diarrhea may be aggravated by emotional stress or eating.
with ibs
 Female predominance. Gas and Flatulence
 IBS symptoms tend to come and go over time and often  Frequently complain: abdominal distention and increased
overlap with other functional disorders such as fibromyalgia, belching or flatulence visible distention with increase in
headache, backache, and gut sx. abdominal girth. Common in:
 Females
 Higher overall Somatic
 Patients with IBS tend to reflux gas from the distal to the more
proximal intestinebelching.
 Patient with bloating:
 Lower thresholds for pain
 More desire to defecate
 25 and 50%- dyspepsia, heartburn, nausea, and vomiting
 The prevalence of IBS is higher among patients with
dyspepsia (31.7%)

PATHOPHYSIOLOGY
1. Abnormal gut motor and sensory activity
CLINICAL FEATURES 2. Central neural dysfunction
 Affects all ages 3. Psychological disturbances
 Most patients have their first symptoms before age 45 4. Mucosal inflammation
 Women 2-3x as often as men and make up 80% of the 5. Stress
population with severe IBS. 6. Luminal factors
 Pain or abdominal discomfort- is a key symptom for the
diagnosis of IBS. Gastrointestinal Motor Abnormalities
 Sx should improved with defecation and/or have their onset  Increased rectosigmoid motor activity for up to 3 h after
associated with a change in frequency or form of stool. eating.
 Painless diarrhea or constipation does not fulfill the diagnostic  Inflation of rectal balloons both in IBS-D and IBS-C patients
criteria. leads to marked and prolonged distention-evoked contractile
 Supportive symptoms that are not part of the diagnostic activity
criteria include defecation straining, urgency or a feeling of
incomplete bowel movement, passing mucus, and bloating Visceral Hypersensitivity
 Patients frequently exhibit exaggerated sensory responses to
Abdominal Pain visceral stimulation
 Abdominal pain or discomfort  prerequisite clinical feature  >2x-perceptions of food intolerance
of IBS.  Postprandial pain has been temporally related to entry of the
 Highly variable in intensity and location. food bolus into the cecum in 74% of patients
 Episodic and crampy, but it may be superimposed on a 1. Increased end-organ sensitivity with recruitment of “silent”
background of constant ache. nociceptors
 Pain may be mild enough to be ignored or it may interfere with 2. Spinal hyperexcitability with activation of NO and possibly
daily activities. other neurotransmitters
 Usually during waking hours. 3. Endogenous (cortical and brainstem) modulation of caudad
 Severe IBS: frequently wake repeatedly during the night. nociceptive
 Pain is often exacerbated by eating or emotional stress 4. Transmission over time, the possible development of
 Improved by passage of flatus or stools. longterm hyperalgesia due to development of neuroplasticity
 Female worsening symptoms during the premenstrual and Central Neural Dyregulation
menstrual phases.

Altered Bowel Habits

 Alteration in bowel habits is the most consistent clinical
feature in IBS.
 The most common pattern is constipation alternating with
diarrhea, usually with one of these symptoms predominates
 Stools are usually hard with narrowed calibre
 Sense of incomplete evacuation

TRANSCRIBER Team Rocket

 INTERNAL MEDICINE
Irritable Bowel Syndrome EXEMIUS
DR. CHRISTINE B. SUBIA December 2019 2021
 Strongly suggested by the clinical association of emotional DIARRHEA: Major complaint
disorders and stress with symptom exacerbation and the  Lactase deficiency
therapeutic response to therapies that act on cerebral cortical  Laxative abuse
sites.  Malabsorption
 Preferential activation of the prefrontal lobe contains a  Celiac sprue
vigilance network within the brain that increases alertness  Hyperthyroidism
 IBD
Abnormal Physiological Features  Infectious diarrhea
 80% of IBS patient has psychiatric features
 Psychological factors influence pain thresholds in IBS patients CONSTIPATION: Major complaint
 Abuse associated with greater pain reporting, psychological  Side effect of many different drugs(anticholinergic,
distress, and poor health outcome antihypertensive, and antidepressants)
 MRI: greater activation of the posterior and middle dorsal  Endocrinopathies (hypothyroidism and hypoparathyroidism)
cingulate cortexCNS–enteric nervous system dysregulation
DIAGNOSTICS
POST-INFECTIOUS IBS  Complete blood count
Risk factors for developing postinfectious IBS:  Sigmoidoscopic examination
 Prolonged duration of initial illness  Stool exam
 Toxicity of infecting bacterial strain  Sigmoid colon biopsy to rule out microscopic colitis.
 Smoking  Age >40 years aircontrast barium enema or colonoscopy
 Mucosal markers of inflammation  Primary sx are diarrhea and increased gas, the possibility of
 Female gender lactase deficiency should be ruled out with a hydrogen breath
 Depression test or with evaluation after a 3-week lactose-free diet
 Hypochondriasis  Celiac sprue-serology testing
 Adverse life events in the preceding 3 months  Dyspepsiaupper GI radiographs or
 Campylobacter, Salmonella, and Shigella esophagogastroduodenoscopy

Immune activation and mucosal inflammation TREATMENT

 IBS px’s show persistent signs of low-grade mucosal PATIENT COUNSELING AND DIETARY ALTERATIONS
inflammation with activated lymphocytes, mast cells, and  Reassurance and careful explanation
enhanced expression of proinflammatory cytokines.  Aggravating: substances (such as coffee, disaccharides,
 These abnormalities may contribute to abnormal epithelial legumes, and cabbage
secretion and visceral hypersensitivity  Excessive fructose and artificial sweeteners, such as sorbitol or
 Mucosal inflammation can lead to increased expression of mannitol, may cause diarrhea, bloating, cramping, or
TRPV1 in the enteric nervous system flatulence.

Altered Gut Flora STOOL-BULKING AGENTS

IBS patients had:  High-fiber diets and bulking agents, such as bran or
 Decreased proportions of the genera Bifidobacterium and hydrophilic colloid, are frequently used in treating IBS.
Lactobacillus  Fiber supplementation with psyllium has been shown to
 Increased ratios of Firmicutes:Bacteroidetes. reduce perception of rectal distention, indicating that fiber
may have a positive effect on visceral afferent function.
APPROACH TO THE PATIENT: Irritable Bowel Syndrome  Fiber should be started at a nominal dose and slowly titrated
Clinical features suggestive of IBS include the following: up as tolerated over the course of several weeks to a targeted
 Recurrence of lower abdominal pain with altered bowel habits dose of 20–30 g of total dietary and supplementary fiber per
over a period of time without progressive deterioration day.
 Onset of symptoms during periods of stress or emotional
upset
 Absence of other systemic symptoms such as fever and weight
loss, and small-volume stool without any evidence of blood

DIFFERENTIAL DIAGNOSIS
 Epigastric or periumbilical area: biliary tract disease, PUD,
intestinal ischemia, and carcinoma of the stomach and
pancreas
 Lower abdomen: diverticula, IBD or carcinoma of the colon
 Postprandial pain+ accompanied by bloating, nausea, and
vomiting- gastroparesis or PGO
 Intestinal infestation with Giardia lamblia or other parasites
may cause similar symptoms.

TRANSCRIBER Team Rocket

 INTERNAL MEDICINE
Irritable Bowel Syndrome EXEMIUS
DR. CHRISTINE B. SUBIA December 2019 2021
ANTISPASMODICS
 Anticholinergic drugs may provide temporary relief for
symptoms such as painful cramps related to intestinal spasm.
 Most effective when prescribed in anticipation of
predictable pain
 Postprandial pain is best managed by giving
antispasmodics 30 min before meals so that effective blood
levels are achieved shortly before the anticipated onset of pain

ANTI-DIARRHEAL AGENTS
 Peripherally acting opiate-based agents are the initial therapy
of choice for IBS-D.
 Increases in segmenting colonic contractions, delays in fecal
transit, increases in anal pressures, and reductions in rectal
perception.
 Loperamide, 2–4 mg every 4–6 h up to a maximum of 12 g/d-
when diarrhea is severe in IBS
 These agents are most useful if taken before anticipated
stressful events that are known to cause diarrhea.

ANTI-DEPRESSANT DRUG
 Mood-elevating effects have several physiologic effects that
suggest they may be beneficial in IBS
 TCA’s- slows jejunal migrating motor complex transit
propagation and delays orocecal and whole-gut transit,
indicative of a motor inhibitory effect
 (SSRI) Paroxetine - accelerates orocecal transit, raising the
possibility that this drug class may be useful in IBS-C patients.

ANTI-FLATULENCE THERAPY
 Patients should be advised to eat slowly and not chew gum or
drink carbonated beverages.
 If bloating is accompanied by diarrhea and worsens after
ingesting dairy products, fresh fruits, vegetables, or juices,
further investigation or a dietary exclusion trial may be
worthwhile.
 Avoiding flatogenic foods, exercising, losing excess weight, and
taking activated charcoal are safe but unproven remedies

MODULATION OF GUT FLORA

 Nonabsorbed oral antibiotic Rifaximin is the most thoroughly
studied antibiotic for the treatment of IBS
 Rifaximin at a dose of 550 mg two times daily for 2 weeks
experienced substantial improvement of global IBS symptoms
 10 probiotic studies in IBS patients found significant relief of
pain and bloating with the use of:
 Bifidobacterium breve
 B. longum
 Lactobacillus acidophilus

TRANSCRIBER Team Rocket