Oesophagus and its disorders

Question 1

Describe the anatomy of the oesophagus (3)

Answer 1

• Fibromuscular tube (25cm) of striated squamous epithelium
• Lies posterior to the trachea
• Begins at end of laryngopharynx and joins stomach a few cm from diaphragm (at the cardiac orifice of the stomach)

Question 2

What does the oesophagus secrete?

Answer 2

Mucus

Question 3

What promotes the transport of ingested food into the stomach?

Answer 3

• This is a highly coordinated muscular process; involves contraction and relaxation of the oesophagus which transports the food through the GIT
• Relaxation of the sphincters (UOS and LOS)

Question 4

What muscle surrounds the oesophagus and at what positions?

Answer 4

• Skeletal muscles surround the oesophagus below the pharynx (the upper third)
• Smooth muscles surround the lower two thirds

Question 5

What are the two sphincters of the oesophagus?

Describe there structures

Give the intrinsic and extrinsic component oF the LOS

Answer 5

Upper oesophageal sphincter (UOS): striated muscle;
Musculo-cartilaginous structure
Constricted to avoid air entering the oesophagus

• Lower oesophageal sphincter (LOS): smooth muscle; acts as a flap valve
LOS = area of high pressure zone
LOS has intrinsic and extrinsic components
Intrinsic component: oesophageal muscles; under neurohormonal influence
Extrinsic component: diaphragm muscle (adjunctive external sphincter)

Question 6

The lower oesophageal sphincter has intrinsic and extrinsic components.

What are the intrinsic components of the LOS?

Answer 6

1. Thick circular smooth muscle layers and longitudinal muscles
2. Clasp-like semi-circular smooth muscle fibres on the right side
   Myogenic activity (some resting tone), but less ACh-responsive
3. Sling-like oblique gastric (angle of His) muscle fibres on the left side
   Working in concert with the clasp like-semicircular smooth muscle fibres, help to prevent regurgitation- responsive to cholinergic innervation
   Angle of His is poorly developed in infants as it makes a vertical junction with stomach, hence why reflux is common in infants

Question 7

What are the extrinsic components of the LOS?

Answer 7

Crural diaphragm encircles the LOS
= Forms channel through which oesophagus enters the abdomen

Fibres of the crural portion of the diaphragm possess a “pinchcock-like” action (extrinsic sphincter; diaphragmatic sphincter)- myogenic tone

Question 8

Describe the innervation of the oesophagus

Answer 8

Involvement of cholinergic (i.e. via ACh) and non-cholinergic, NANC innervation in the control of tone of the lower oesophageal sphincter

Neural control of the oesophageal sphincters

• Acetylcholine, SP: contraction of intrinsic sphincters
• NO and VIP: relax the intrinsic sphincters
• Extrinsic and intrinsic sphincters work in concert to push the food into the stomach

Question 9

Describe other nerves of the oesophageal plexus

Answer 9

DVN: dorso vagal nucleus;
NA: nucleus ambiguus;
NTS: nucleus tractus solitarius

Question 10

Describe Oesophageal motor innervation

What 2 post-ganglionic fibres in the myenteric plexus does ACh affect?

Answer 10

The striated muscle of the upper oesophagus is innervated directly by the somatic efferent cholinergic fibres of the vagus nerve originating from the nucleus ambiguus.
Smooth muscle of the distal oesophagus is innervated by the preganglionic vagus nerve fibres from the dorsal motor nucleus. ACh affects two types of post-ganglionic neurons in the myenteric plexus: excitatory cholinergic neurons and inhibitory nitrinergic neurons via NO, VIP

Question 11

Describe the functions of the oesophagus?

Answer 11

• Swallowing (deglutition)

* Conveys food and fluids from pharynx to stomach

Question 12

How is swallowing initiated?

Answer 12

1. Voluntary action – collect material on tongue and push it backwards into pharynx (skeletal muscle, mucus membrane)
2. Waves of involuntary contractions push the material into oesophagus

Question 13

Where does food move?

Answer 13

Food moves from Mouth→oropharynx →laryngopharynx→oesophagus and stomach

Question 14

What reflex responses are initiated to swallow?

Answer 14

• Reflex responses
• Inhibition of respiration (breathing)- nasopharynx is closed off
• Closure of glottis (around the vocal cords) by epiglottis
• Prevents food from entering the trachea
• Ring of peristaltic waves (4cm/sec) behind the material moves it towards the stomach
• A second wave of peristalsis moves any food remnants along

Question 15

What is swallowing difficulty caused by?

Answer 15

Swallowing difficulty (oropharyngeal dysphagia) is caused by the inability of the UOS to open or discoordination of the timing between the opening of UOS and the pharyngeal push of ingested bolus

Question 16

When food passes through the oesophagus when does the UOS and LOS open and close?

What happens during secondary peristalsis

Answer 16

Relaxation of upper oesophageal sphincter (UOS) – food passes

1. UOS closes as soon as food passes
2. Glottis opens
3. Breathing resumes

Lower oesophageal sphincter opens and stays open throughout swallowing

LOS closes after material has passed

A large food material does not reach the stomach after the first peristaltic wave

Stimulation of receptors upon distension of the lumen of the oesophagus by the food → repeated waves of peristalsis (secondary peristalsis)
Is secondary peristalsis of any benefit?

Question 17

What prevents the reflux of gastric contents

Answer 17

1. LOS – closes after material has passed
2. “Pinchcock” effect of the diaphragmatic sphincter on the lower oesophagus (side-to-side compression between “2 pillars” of the crus)
3. Plug-like action of the mucosal folds in the cardia– occludes the lumen of the gastro-oesophageal junction:
   - Abdominal pressure acting on the intra-abdominal parts of the oesophagus

• Valve-like effect of oblique entry of oesophagus into stomach – in adults only

Sphincter muscles of UOS and LOS = strong circular muscles; act as valves to control the movement of the food mass aborally (forward direction); prevent reflux by forming an opening when relaxed and closing completely when contracted

Overall, there is an anti-reflux barrier in the region of gastro-oesophageal junction

Question 18

Give an overview of the types of oesophageal disorders

Answer 18

• Disorders of motility or peristalsis of oesophagus (assess the motor function of the UOS, LOS and oesophageal body) (achalasia)
• Assess cause of regurgitation (e.g. reflux of stomach acids into oesophagus); weak LOS (GORD)
• Aphagia (determine cause of swallowing difficulty)
• Abnormal oesophageal contractions and food is not effectively reaching the stomach (oesophageal spasm)
• Diffuse oesophageal spasm - chest pain coming from oesophagus (~angina)

Question 19

What is an achalasia?

What does it result in ( and show on oesophageal)?

What does it result in?

Answer 19

• Impaired LOS relaxation (spasms)
• Can be accompanied by impaired peristalsis (sphincter spasms);
• Food and liquids fail to reach the stomach – delayed opening of LOS;
• Results in dilation of oesophageal body with distal narrowing (bird’s beak appearance) of the barium-filled oesophagus on oesophagram;
• Long period of sporadic dysphagia (difficulty swallowing);
• Regurgitation of food

Question 20

Describe the aetiology of achalasia

Answer 20

1. Disorders of motility or peristalsis of oesophagus (assess the motor function of the UOS, LOS and oesophageal body)
2. Damage to the innervation of oesophagus
3. Degenerative lesions to the vagus nerve and loss of myenteric plexus ganglionic cells in the oesophagus

Question 21

What are the symptoms of achalasia?

Answer 21

• Dysphagia
Difficult or painful swallowing
• Vomiting
• Heartburn

Retrosternal burning sensation due to oesophageal dysmotility

Retention of ingested (acidic) food;

Generation of lactic acid in the process of decomposition of retained food;

also heartburn could be caused by the retention of small quantities of acid refluxed in the oesophagus due to poor emptying and incomplete relaxation of LOS

Question 22

How do doctors diagnose achalasia?

Answer 22

1. Barium radiography (barium swallow): dilatation of oesophagus with beak deformity at lower end -Evaluates the entire swallowing channel (mouth, pharynx, and oesophagus)
2. Oesophageal manometry: absent peristalsis

Question 23

Why is Oesophageal manometry performed?

Answer 23

To determine the cause of non-cardiac chest pain
To evaluate the cause of reflux (regurgitation) of stomach acid and other contents back up into the oesophagus (GORD?)
To determine the cause of difficulty with swallowing food (does UOS/LOS contract and relax properly?)
Allows evaluation of strength of coordination of muscle contractions
Relaxation function of LOS

Question 24

What are the normal results of oesophageal manometry

Answer 24

Normal LOS pressure and normal muscle contractions upon swallowing
Low LOS pressure suggests GORD, but GORD can occur in individuals with normal LOS pressure
What does high LOS pressure suggest?
Pressure of LOS <26mm Hg is normal, >100 mm Hg is considered achalasia, > 200 mm Hg is nut cracker achalasia

Question 25

What would normal results of oesophageal manometry show?

Answer 25

The pressure of the muscle contractions that move food down the oesophagus is normal The muscle contractions follow a normal pattern down the oesophagus Normal pressure of the LOS is about 15 mmHg, but *when the LOS relaxes to let food pass into the stomach, the pressure is less than 10 mmHg

Question 26

What are abnormal results of oesophageal manometry characterised by?

Answer 26

Presence of muscle spasms in the oesophageal body Presence of weak contractions along the length of the oesophagus *The LOS pressure is less than 10 mmHg (GORD?) – do not confuse these 2 Characterised by high LOS pressure which fails to relax after swallowing Lack of a coordinated LOS relaxation in response to swallowing.

Question 27

What happens in reflux in normal individuals? When does it happen? What does saliva do to reflux acid? What does a low rate of salivation cause/ lack of ability to swallow saliva?

Answer 27

* Often occurs after meals in normal individuals (- transient spontaneous LOS relaxation, tsr); * Reflux usually stimulates salivation * Saliva is an effective natural antacid - dilutes and neutralises refluxed gastric contents * Low rate of salivation; lack of ability to swallow own saliva →prolongation of contact of refluxed material with oesophagus → Gastro-oesophageal reflux disease due to oesophageal irritation and oesophageal damage

Question 28

What is Gastro-oesophageal reflux disease (GORD)?

Answer 28

GORD is when reflux is more frequent and troublesome Low rate of salivation; lack of ability to swallow own saliva →prolongation of contact of refluxed material with oesophagus → oesophageal irritation and oesophageal damage.

Question 29

What are the causes of refluxes with those who have GORD?

Answer 29

1 Transient spontaneous LOS relaxation (tsr) 98% of reflux events in normal individuals is associated with transient spontaneous relaxation (tsr) of LOS 2. Resting LOS pressure is too weak to resist the pressure within the stomach 3. Sudden relaxation of the LOS that is not induced by swallowing

Question 30

What factors contribute towards the severity of GORD?

Answer 30

1. Weak or uncoordinated oesophageal contractions (oesophageal irritation from reflux disease itself?) – prolonged duration of contact of refluxed digestive contents with oesophagus 2. Length of time the oesophagus is exposed to gastric acid ↑ Gastric acid secretion coupled with presence of bile in gastric contents → severe oesophageal damage 3. Amount of pressure placed on the anti-reflux barrier Reflux occurs after eating, lying down (supine), and when there is delayed gastric emptying Impaired gastric emptying alone can cause severe GORD

Question 31

How can GORD be investigated?

Answer 31

Low dose proton pump inhibitor (PPI) challenge is 1st line Upper GI endoscopy Manometry 24-hr ambulatory pH monitoring

Question 32

How does GORD and pregnancy interact?

Answer 32

1. Foetus increases pressure on abdominal contents 2. Pushes terminal segments of oesophagus into thoracic cavity 2. Last trimester of pregnancy is associated with increased abdominal pressure and this forces gastric contents into oesophagus 3. Heartburn subsides in the last months of pregnancy as uterus descends into pelvis

Question 33

What causes normal heartburn?

Answer 33

May occur in some individuals upon eating large meals Less efficient LOS Gastric contents episodically refluxed into oesophagus Heartburn Ulcer, scarring, obstruction or perforation of lower oesophagus on image

Question 34

What are the long term effects of GORD?

Answer 34

Oesophagitis, oesophageal strictures Squamous cell carcinoma Barrett's syndrome - this may predispose someone to oesophageal adenocarcinoma Oesophageal ulcer

Question 35

Manometry will be ordered if you have symptoms of:

Answer 35

Heartburn or nausea after eating (GORD) | Problems swallowing [feeling that food is stuck behind the breast bone (achalasia)]

Question 36

How can GORD be managed?

Answer 36

Life-style changes - raise head of bed at night, weight loss, modify food ↓ Intake of foods and drink which cause symptoms Anti-reflux surgery (fundoplication – wrap fundus around LOS) Take antacids H2 receptor antagonists and proton pump inhibitors Metoclopramide/domperidone – may enhance peristalsis and help gastric acid clearance

Question 37

List of lifestyle changes that help alleviate the symptoms of GORD

Answer 37

``` Some people need to avoid large meals Lose weight (if overweight) Avoid foods that increase gastric acidity Avoid foods that slow gastric emptying Avoid lying down after meals - elevate the head of the bed Avoid some drugs and smoking Decease fat intake ``` Basically, if you know what aggravates the symptoms, you can try to implement life-style changes that may help alleviate the onset

Question 38

How can antacids be used to treat GORD?

Answer 38

Neutralise gastric acid; ↑ pH of gastric lumen | Inhibit peptic activity and stop acid secretion

Question 39

What are the side effects of antacids?

Answer 39

``` Magnesium salts→ diarrhoea Aluminium salts→ constipation Use a mixture of 2 to ensure bowel function Combine alginates (e.g. gaviscon) with antacids for oesophageal reflux Alginic acid + saliva form a raft which floats on content of gastric lumen and protects the oesophageal mucosa from reflux ``` All of the above agents ↓ acid secretion and help heal the ulcer, but removal of H. pylori is essential to stop ulcer returning.

Question 40

Why study oesophageal disorder?

Answer 40

Complications of GORD Oesophagus has squamous mucosa * Acid reflux → desquamation of oesophageal cells (injury of squamous mucosa) * ↑ cell loss → basal cell hyperplasia * Excessive desquamation → ulceration * Ulcers may haemorrhage, perforate or heal by fibrosis with strictures This leads to Barrett’s oesophagus and oesophageal cancer