Neurogastroenterology

Question 1

What is the enteric NS?

Answer 1

• Enteric nervous system= composed at level of gut 2 plexus lie between circular and longitudinal muscles, structure present throughout tract
• -Interaction between 2 plexuses and visceral NS, connections to central NS
• Web of interconnected neurones to connect gut to brain

Question 2

Describe the basic structure of the enteric NS

Answer 2

• Myenteric and submucosal plexi

- In between longitudinal and circular muscle with connective tissue

Question 3

What are the types of neurones in the NS?

Answer 3

• Sympathetic (adrenergic)
• Parasympathetic (cholinergic)
• Enteric (mainly 5HT)

Question 4

What are the investigations for GI presentation?

Answer 4

• FBC, ESR, U&E, LFTs, TFT’s
• TTG for coeliac disease
• Stool for microscopy and culture X2
• Faecal calprotectin (inflammation)
• Abdominal ultrasound
• Colonoscopy
• Small bowel MRI scan

Question 5

What is the the criteria for IBS?

Answer 5

Rome 1V
-Abdominal pain 
AND 2 of
-Related to defecation
-Change in stool frequency
-Change in stool form
Symptoms over 6/12 on average weekly for last 3/12

Question 6

Describe the multifactorial pathophysiology of IBS

Answer 6

• Abnormal motor function
• Visceral hypersensitivity
• Brain-Gut interaction
• Role of 5HT
• HPA stress response
• Immune activation
• Genetics
• Microbiota
• CNS pain processing

Question 7

What are the mechanisms of pain in IBS?

Answer 7

• motor function
• peripheral sensory function
• spinal processing
• central processing
• cortical activation
• descending CNS modulation

Question 8

What are the IBS subtypes?

Answer 8

• D for diarrhoea
• C for constipation
• M for mixed
• 25% of BM is the threshold for classification

Question 9

Describe the link between visceral hypersensitivity and IBS

Answer 9

• Visceral hypersensitise= find colonoscopy more uncomfortable- sign of IBS? Inflating balloon= when can they perceive balloon is lower pain threshold, somatic threshold normal/ higher in IBS
• -Psychological= stress and anxious, amplify signals= IBS who go to doctors have markers of psychopathology

Question 10

What are the symptoms of IBS?

Answer 10

• Onset following gastroenteritis
• Post-prandial urgency
• Alternating diarrhea/constipation
• Passing mucus
• Sensation of incomplete evacuation
• Abdominal bloating
• Abdominal distention

Question 11

What other conditions are associated with IBS?

Answer 11

• Migraine
• Dyspepsia
• Dyspareunia
• Bladder problems
• Fibromyalgia
• Chronic fatigue

Question 12

What alarm features suggest another diagnosis?

Answer 12

• Weight loss
• Rectal bleeding,
• Anaemia, thrombocytosis
• Persistent diarrhoea (lack of day-day variability)
• New onset over 50 yrs
• Frequent nocturnal symptoms
• FHx bowel cancer/IBD

Question 13

How is IBS managed?

Answer 13

• Lifestyle advice (exercise), first line dietary advice (BDA diet sheet)
• Dietary therapy, low FODMAP, lactose restriction, wheat/gluten restriction
• Drug therapy (based on predominant symptoms)
• Psychological therapies, CBT, hypnotherapy, relaxation therapy

Question 14

What is the drug therapy for pain/bloating?

Answer 14

-Antispasmodic (NNT=3)
 =Peppermint oil
 =Mebeverine
 =Hyoscine
-Tricyclic  (NNT=4) *
 =Amitriptyline
 =nortriptyline, imipramine less sedating
-?Rifaximin* (NNT =11)

Question 15

What is the drug therapy for diarrhoea?

Answer 15

-Loperamide (NNT=3)
-Ondansetron*
(NNT=2.7)
-Tricyclic *
-(Alosetron NNT =7)
-(Eluxadoline NNT=8 )
-?Rifaximin *

Question 16

What is the drug therapy for constipation?

Answer 16

-Ispaghula
-Macrogol
-Linaclotide (NNT=4 constip)
(NNT=7 pain)
-(Lubiprostone)
-(Prucalopride)
-?SSRI *