Irritable Bowel Syndrome IBS Flashcards
Symptoms of IBS
“swinging bowl habit”- periods of constipation and periods of diarrhoea
-alone doesnt mean benign, as other conditions can cause change in bowel habit including cancers
Abdominal pain typically relieved with defaecation
-bloating.
Associated symptoms:
-urgency, feeling of incomplete evacuation.- need to return in 5-10 mins. pain and have to return quickly in order to relieve pain
-passage of mucus (not nescessarily of concern or pathological) just often seen in IBS
-abdominal bloating (sometimes more a feeling of distention and discomfort, more than “pain”)
-excess flatus
May occur after (acute infective) gastoenteritis (salmonella or camplobacter)
-after acute infective illness fail to regain normal bowel habit
-post-infective IBS
-Theory: 1. imbalance in normal flora after acute infective insult.
2. infective pathogen caused neurological damage, effecting gut motility
Rome criteria III IBS
Rome III-newest version
IBS is a functional digestive disorder
3. characterised by abdominal pain or discomfort
2. and changed in stool frequency or consistency
-atleast 3 days per month in the last 3 months
1. Chronic disorder:(months-years- usually years in younger person)
-onset of symptoms atleast 6 months prior to diagnosis
-must be associated with two or three of the following:
4. –improves with defecation
5. –onset of pain coincides with changes in stool frequency
(periods of feeling really well for weeks/months, but then may have relapse in symptoms of abdominal pain and diarrhoea again)
–onset of symptoms is accompanied by changes in the form or appearance of stool
Associated symptoms of IBS
- Fatigue
-dont have to be present in every person with IBS
Other functional GI symptoms:
-functional dyspepsia
-Early satiety, post prandial fullness (early or prior to completion of meal)
-Nausea, vomiting (vomiting normally not common symptom assoc. with IBS) - Backache, Head ache (non specific)-feeling generally unwell sometimes
- Urinary symptoms (urinary frequency)
- Dysmenorrhoea (painful periods), dyspareunia
-if woman with IBS also have menstrual symptoms, have to consider endometriosus (can sometimes cause IBS like symptoms in woman, and can be assoc. with painful periods) - Palpitations
- Poor sleep quality
Post infective IBS
May occur after (acute infective) gastoenteritis (salmonella or camplobacter)
- after acute infective illness fail to regain normal bowel habit
- post-infective IBS
- Theory: 1. imbalance in normal flora after acute infective insult.
2. infective pathogen caused neurological damage, effecting gut motility
Alarm symptoms
- Older patient (over 50, but even 40+ should re-consider other diagnosis
- IBS typically occurs in younger people (born with or had for a long time) - Short history
- IBS is a chronic problem. Sudden change in bowel habit of constipation or diarrhoea, esp if only few weeks - Nocturnal diarrhoea/nocturnal pain (unusual for IBS)
- Rectal bleeding (suggest inflammation, doesnt occur in IBS and IBS has no abnormality in mucosa)
- Anaemia or iron deficiency
- chronic or gult GI blood loss –> malabsorption. IBS has no problems with absorption - Weight loss (severe IBS can report minimal weight loss, but more related to reduced oral intake due to symptoms) - weight-loss should be taken seriously
- Vomiting (sometimes occurs with functional conditions - IBS or cyclical vomiting syndrome, but should be diagnosis of exclusion as Vomiting may indicate pathology
- Family history of colon cancer (increases risk of pathology)
How common is IBS
-most common functional GI disease or disorder
Community studies: (1/5)
5-12%men
5-18% women (based on Rome criteria-for purposes of research)
But if not strictly based on criteria more than this- clinically would be more common (1/4)
Usually early onset
-age 20s- early 30s
IBS pathophysiology
Pthophysiology is complex
- alot still not known re how and why IBS occurs
1. Altered gut motility (complex and varible types of symptoms-constipation, diarrohea, both) - clearly impaired and too slow sometimes, other times clearly hyperstimulated
- frequency and duration of contractions
- transit time
- exaggerated response to meal ingestion/stress (need to empty bowel soon after eating. not malabsorption. more exaggerated gastro-colic reflex, stomach expands during meal stimulating colon to contract –> sensation of needing to go toilet). Stress (symptoms worse in stressful situations
- in simple terms-exaggerated with diarrhoea, reduced with constipation
2. Visceral Hypersensitivity (+ manner of perceiving gut stimuli) - balloon distention of colon causes pain in 50-60% of IBS patients compared with 10% of controls (recognise pain with lower thresholds of distention vs healthy controls)- not clear why
- IBS patients describe gut stimuli as unpleasant or painful at lower intensity than controls (distention perceived differently (feeling of stretching vs painful and pleasant)
Mechanisms of Visceral hypersensitivity
In some patients with IBS, symptoms started after an episode of gastroenteritis (post-infective IBS) (degree of sensitisation)
Previous tissue inflammation/injury may upregulate sensitivity and excitability of (pain) nociceptors, leading to:
- hyperalgesia (increased sensitivity to painful stimuli)
-allodynia (non-painful stimuli perceived as pain)
Results in peripheral sensitisation of any painful stimuli
Mechanisms of Visceral hypersensitivity - Central sensitisation
Peripheral sensitisation (upregulation of receptors in repsonse to previous injury) may lead to surrounding uninjured tissue to become hypersensitive as well In IBS, some patients have pain radiating beyond the gut (along side pain inside gut) -e.g. IBS patients with fibromyalgia (functional syndrome with muscle and joint aches) (may be due to innervation of gut converging with innervation of somatic structures at the level of the spinal cord) and headaches, backaches -overall increased sensitisation, to gut and other muscle and nerves in body
Mechanism of visceral hypersensitivity: central pain processing
Brain processing of visceral sensation may be different in IBS
- processing of pain stimulus may be impaired or altered
- MRI scans of some people with IBS light up differently compared to healthy controls
- had distention of the rectum with ballon
- -“different parts of the brain seem to be involved with the perception of the distention in people with IBS compared to health controls”
- fMRI imaging with rectal distention in IBS
Mechanism of visceral hypersensitivity: gate control theory
pain messages from periphery have to encounter “nerve gates” in spinal cord before reaching the brain
-If gate opened= stimulus reaches to brain
-if gate closed= does not reach/perceive brain (stimulus cut off at level of spinal cord)
-naturally brian is able to ignore certain stimulus and pay attention to others
Hypervigilance: Brain focuses (increased) on processing unpleasant stimuli
-regulated worse
-processes differently + becomes more aware of any unpleasant stimulus
Mechanism of visceral hypersensitivity: effect on stress
Brain-gut communication is bi-directional
(brain talks to gut and gut talks to brain)
(gut function can affect the food of patients with IBS)
Brain can influence motor, sensory, secretory and immune functions of GI tract
IBS treatment
- v different to IBD
- Functional conditions sometimes difficult as dont know pathology. Therefore have to employ wide range of modalities
1. Conventional:
2. Dietary
3. Natural
4. Lifestyle
Conventional IBS treatment
- Fibre supplements
- gut motility (predominant constipation) to improve bowel movements
- may aggravate symptoms (up to 2-3) - worsening esp “bloating” - Laxative for constipation
- Osmotic (preferred as no long term effects on bowel function. act as osmotically active particle) and stimulant laxatives - Anti-motility drugs for bowel frequency
- diarrhoea. Loperamide - Low-dose tricyclic antidepressants
- amitriptyline, nortriptyline
- works for neuropathic pain (blocks various neurotransmitters and receptors involved in pain perception)
- dont treat mood, depression or anxiety. more to treat pain. also used for chronic pain syndromes
Dietary exclusions for IBS treatment
Based on concept of IBS as multiple food sensitivities
-intolerance rather than allergy
-there are some foods that percipitate their symptoms
Diet based on food diaries of foods associated with symptoms
50-60% response rate
-depends on enthusiasm/vigilance of patient and dietitian
Food allergy not likely to have a role in IBS
-skin tests and RAST tests do not seem to help
Recent interest in FODMAPs diet
