31) Oesophagus and its disorders

Question 1

What is the oesophagus?

Answer 1

• It is a fibromuscular tube of striated squamous epithelium which lies posterior to the trachea
• It beings at the end of the laryngopharynx and joins the stomach at the cardiac orifice
• It transports food to the stomach. In order to aid this function it secrets mucus for lubrication and also protection of the surface of the oesophagus
• The oesophagus is well protected as it is susceptible to erosion by digestive juices

Question 2

What is the angle of His?

Answer 2

• The acute angle created between the oesophagus and the fundus.
• It is not well developed in infants and therefore is why reflux is more common in infants.

Question 3

How is food moved through the oesophagus?

Answer 3

• There is a highly coordinated muscular processes which involves primary and secondary peristalsis through contractions and relaxations of the oesophageal body
• We also need the relaxation of the sphincters starting with the upper oesophagus sphincter (UOS) and once food enters it closes and peristalsis occurs as it passes down the oesophagus

Question 4

What are the different sphincters within the oesophagus?

Answer 4

• Upper Oesophagus Sphincter (UOS): Is a musculo-cartilaginous structure composed of striated muscles. It is constricted to prevent air entering the oesophagus
• Lower Oesophagus Sphincter (LOS): Composed of smooth muscles and acts as a flap valve. It is a high pressure zone because there is food in the stomach which creates pressure. It has intrinsic and extrinsic components which allow the oesophagus to remain contracted to prevent food reflux occuring

Question 5

What are the different components in the LOS?

Answer 5

• Extrinsic and intrinsic sphincters work in unity to push food through into the stomach.
• Malfunction of the intrinsic and extrinsic components of the LOS can lead to Gastroesophageal Reflux Disease (GORD)

Question 6

What is the intrinsic component of the LOS?

Answer 6

• Thick circular smooth muscle layers and longitudinal muscles which work in concert in which contractions are mediated acethylcholine and relaxations are mediated by NO and VIP.
• Clasp-like semi-circular smooth muscle fibres on the right side of the LOS which have myogenic activity that can initiate electrical activity due to the cells they contain. They are self sufficient and so are less responsive to acethylcholine
• Sling like oblique gastric muscle fibres (angle of his) found on the lfet side of the oesophagus which works in concert with the clasp-like semi-circular smooth muscle fibres to help prevent regurgitation and are very responseive to acetylcholine

Question 7

What is the extrinsic component of the LOS?

Answer 7

• Diaphragmatic muscles that encircles the LOS forms channels through which the oesophagus enters into the abdomen
• These fibres provide a “pinchcock-like” action where they act as an extrinsic diaphragmatic sphincter through myogenic tone (relies on cell within to promote their activity) to prevent regurgitation

Question 8

How is the upper part of the oesophagus innervated?

Answer 8

• Upper part: Striated muscles are supplied by somatic motor neurones of vagus nerve without interruptions. It is also innervated by splanchnic nerves which can initiate a response via the spinal chord leading to the higher centres of the brain

Question 9

How is the lower part of the oesophagus innervated?

Answer 9

• Lower part: Smooth muscles cells are innervated by visceral motor neurones of the vagus nerve with interruptions as there are synapses with post-ganglionic neurones and cell bodies that lie in the oesophagus and splanchnic plexus.
• There is involvement of cholinergic and noncholinergic nerves which allow for the contraction and relaxation to allow the food to make its way into the stomach.
• The oesophagus is also encircled by nerves of the oesophageal plexus.
• Acetyl choline and gastrin allow contractions of the intrinsic sphincter and NO and VIP cause relaxation of these sphincters

Question 10

What is the function of the oesophagus?

Answer 10

• Swallowing

- Conveys food and fluids from the pharynx to the stomach

Question 11

How do impulses cause swallowing?

Answer 11

• The presence of food triggers swallowing
• Afferent impulses in the glossopharyngeal are sent to the vagal centres
• Integration/ processing of impulses in the nucleus of tractus solitarius (NTS), nucleus ambigus (NA) and dorsal vagal nucleus
• Efferent impulses travel via motor pathways to the pharyngeal musculature, tongue, oesophagus and LOS

Question 12

How is swallowing initiated?

Answer 12

• The initiation of swallowing is voluntary as we put food on our tongue push it backwards into the pharynx through the help of skeletal muscles and mucosal membranes
• The UOS opens to allow food to pass through and closes when it passes
• From here waves of involuntary contractions push the material into the oesophagus
• There is a reflex response where breathing stops to close off the nasopharynx and the glottis (around the vocal chords) by the epiglottis as this prevents food from entering the trachea
• Ring of peristalsis waves pass behind food moving it towards the stomach
• When it reaches teh bottom the LOS opens to allow food into the stomach and closes after the food has passed
• However large food often does not reach the stomach so there is a second way that move any food remnants along the oesophagus (called second wave peristalsis)

Question 13

Describe the pathing of the food.

Answer 13

Mouth –> Oropharynx –> Laryngopharynx –> Oesophagus –> Stomach

Question 14

What prevents the reflux of gastric contents?

Answer 14

• LOS closes after food has passed
• There is a “pinchcock” effect of the diaphragmatic sphincter in the lower oesophagus
• Plug-like action of the mucosal folds in the cardia which occlude the lumen of the gastro-oesophageal junction.
• Sphincter muscles of the UOS and LOS that can contract and act like valves to control the movement of food towards the anus.

Question 15

What is oropharyngeal dysphagia/ aphagia?

Answer 15

• Oropharyngeal dysphagia/ aphagia: Characterised by diffculty swallowing as the UOS is unable to open or discoordination of the timining between the opening of the UOS and the pharyngeal push behind the mass of food

Question 16

What is Oesophageal spasm?

Answer 16

-Abnormal oesophageal contractions and food is not reaching the stomach effectively

Question 17

What is Diffuse oesophageal spasm?

Answer 17

• Chest pain/angina coming form the oesophagus

Question 18

What is Achalasia?

Answer 18

• Disorders of motility or peristalsis of oesophagus

- Asses the motor functions of the UOS, LOS and oesophageal body

Question 19

What is Regurgitation?

Answer 19

• Reflux of stomach acids into the oesophagus due to weak LOS (GORD)

Question 20

What is the pathophysiology of achalasia?

Answer 20

• Initiating factor is thought to be autoimmune or triggered by an infection
• There is impaired LOS relaxation (spasms) which can be accompanied by impaired peristalsis (sphincter spasms) .
• This can be caused by disorders in motility/peristalsis, damage to innervation of the oesophagus or degenerative lesions of the vagus nerve leading to loss of myenteric plexus and ganglionic cells in the oesophagus
• As a result foods and liquids fail to reach the stomach effectively which delays the opening of the LOS
• This results in the dilatation of oesophageal body (due to build up of food) with distal narrowing of the LOS

Question 21

What are the symptoms of achalasia?

Answer 21

• There may be long periods of swallowing (sporadic dysphagia)
• Regurgitation and vomiting
• Heartburn (retrosternal burning sensation)

Question 22

What are the causes of heartburn?

Answer 22

• Oesophageal dysmotility causing retention of ingested (acidic) food.
• This retained food may also generate lactic acid in the process of decomposition.
• Small quantities of gastric acid may also get refluxed in the oesophagus due to poor emptying and incomplete LOS relaxation

Question 23

How to diagnose achalasia?

Answer 23

• Barium radiography: dilatation of oesophagus with beak deformity at lower end
• Oesophageal manometry: absent peristalsis

Question 24

Why is oesophageal manometry carried out?

Answer 24

• Determines the cause of non-cardiac chest pain
• To evaluate the cause of regurgitation of stomach acid and other contents back into the oesophagus
• To determine the cause of difficulty swallowing
  (Overall it evaluates if the oesophagus is contracting and relaxing properly)

Question 25

What do the normal results of a oesophageal manometry show?

Answer 25

• Normal LOS pressure and normal muscle contraction in swallowing
• Muscle contraction follows a normal pattern down the oesophagus
• Normal pressure is about 15 mm Hg in the LOS and is less than 10 mm Hg when food is let out of the stomach. LOS less than 10 mm Hg without emptying can show GORD

Question 26

What do abnormal results in oesophageal manometry show?

Answer 26

• Presence of muscle spasms in the oesophogeal body
• Presensce of weak contractions along the length of the oesophagus
• Achalasia is characterised by high LOS (<100 mm Hg) as the LOS fails to relax after swallowing

Question 27

Why does reflux trigger salivation?

Answer 27

• Saliva is an effective natural antacid which dilutes and neutralises refluxed gastric acid

Question 28

How can reflux lead to GORD?

Answer 28

• If there is a low rate of salivation or lack of ability to swallow own saliva then this can lead to the prolonged contact of refluxed material with the oesophagus
• This can result in GORD

Question 29

What is GORD?

Answer 29

• Retrograde movement of gastric content into the oesophagus due to prolonged relaxation of the LOS
• GORD occurs when reflux is more frequent and troublesome
• GORD causes a burning sensation in the chest after meals
• GORD causes oesophageal irritation and damage

Question 30

What are the causes of GORD?

Answer 30

• Spontaneous LOS relaxation
• Resting LOS pressure is too weak to resist the pressure within the stomach
• Sudden and sustained relaxation of the LOS that is not induced by swallowing

Question 31

What aspects contribute to GORD?

Answer 31

• Weak or uncoordinated oesophageal contractions or poor oesophageal motor activity causing prolonged duration of contact of refluxed digestive contents with the oesophagus
• Length of time oesophagus is exposed to gastric juices. Increase gastric acid secretion along with the presence of bile in gastric contents can cause severe damage to the oesophageal body
• Amount of pressure placed on the anti-reflux barrier
• Reflux occuring after eating, lying down and when there is delayed in gastric emptying
• Impaired gastric emptying can give rise to GORD alone

Question 32

What factors are associated to GORD?

Answer 32

• Pregnancy or obesity
• Type of food (e.g. fats and large meals)
• Drugs

Question 33

How do we investigate GORD?

Answer 33

• Low dose of Protein Pump Inhibitor (PPI)
• Upper GI endoscopy
• Manometry
• 24 hour ambulatory pH monitoring

Question 34

Why is pregnancy associated with GORD?

Answer 34

• There is an increased abdominal pressure which forces gastric contents into the oesophagus
• This occurs during the last trimester and heartburn subsides in the last month as the uterus descends into the pelvis

Question 35

How can heartburn occur in the absence of pregnancy?

Answer 35

• Normally occurs after eating large meals or due to less functional LOS
• Gastric contents are episodically refluxed into the oesophagus causing heartburn
• This can lead to ulcer, scarring, obstruction or perforation of lower oesophagus

Question 36

How is GORD managed or treated?

Answer 36

• Changes in life-style (e.g. raise head of bead at night)
• decrease intake of certain food and drinks
• Anti-reflux surgery (e.g. fundoplication which is where the fundus is wrapped around the LOS). However fundoplication can cause dysphagia (trouble swallowing) as it reduces distensibility of the LOS
• Antacids
• H2 receptor agonists and proton pump inhibitors
• Metoclopramide/domperidone which may enhance peristalsis and help gastric clearance

Question 37

What are some lifestyle changes used to treat GORD?

Answer 37

• Avoid large meals
• Lose weight (if overweight)
• Avoid foods that increase gastric acidity
• Avoid food with slow gastric emptying
• Avoid lying down after meals (elevate head of the bed)
• Avoid smoking and drugs
• Decrease fat intake

Question 38

How does the use of antacids treat GORD?

Answer 38

• They neutralise gastric acid by increasing the pH
• They inhibit peptide activity and stop acid secretion
• Some combine alginates with antacids for oesophageal reflux
• Alginic acid can be combined with saliva to form a raft that floats on the contents of the gastric lumen and protects the oesophageal mucosa from reflux
• These agents help treat ulcers, decrease acid secretion however removal of H.pylori is essential for stopping ulcer returning

Question 39

What are the disadvantages of using antacids to treat GORD?

Answer 39

• Magnesium salts cause diarrhoea
• Aluminium salts cause constipation
• However a mixture of the two can be used to ensure bowel functions adequately

Question 40

What complications does GORD cause?

Answer 40

• Acid reflux can cause desquamation of oesophageal cells causing injury of squamous mucosa
• It can cause cell loss due to basal cell hyperplasia
• It can cause excessive desquamation through ulceration
• Ulcers may haemorrhage, perforate or heal by fibrosis with strictures which can lead to Barrett’s oesophagus and oesophageal cancer

Question 41

What are the potential long term effects of GORD?

Answer 41

• Oesophageal strictures
• Squamous cell carcinoma
• Barrett’s syndrome
• Oesophageal ulcer