Pathophysiology of the Esophagus

Question 1

Characteristics of oral phase of swallowing

Answer 1

• teeth clench, lips seal, tongue propels bolus posteriorly into upper oropharynx
• voluntary control
  
  • involves use of CN V, VII, and XII
    *

Question 2

Characteristics of pharyngeal phase of swallowing

Answer 2

• initiated by food bolus arrival @ post. tongue/pharynx
• involuntary; controlled by CNX and CNIX
• Closure of nasopharynx via retraction and contraction of the soft palate muscles.
• Elevation/closure of the larynx & epiglottis to prevent aspiration
• Relaxation of the cricopharyngeal muscles and maximal elevation of hyoid bone
• Rhythmic pharyngeal constrictor contraction, resulting in passage of bolus down the oropharynx and across the upper esophageal sphincter.

Question 3

Types of oropharyngeal disease

Answer 3

• structural disease i.e. obstruction ==> inability to initiate/complete swallow +/- fullness or pain @ mouth/pharynx
  
  • zenker’s diverticulum
  • cervical osteophytes
  • cricopharyngeal ring/hypertension
  • neoplasm
• neuromuscular disease ==> oropharyngeal dysphagia or aspiration
  
  • CNS problems: stroke, ALS, CN disease
  • muscular: polymyositis, MG, muscular dystrophy

Question 4

Anatomy of the esophagus

Answer 4

• upper 1/3 = striated (skeletal) msucle
  
  • innervated by vagal fibers
• middle 1/3 = mixed striated + smooth
• lower 1/3 = smooth muscle
• **all involuntary control
• peristalsis = wave of contraction
  
  • inner circular smooth m. layer contracts
  • outer longitudinal smooth m. layer contracts ==> movement of squeezing wave
• sphincters
  
  • Upper esophageal sphincter (UES)
  • Lower esophageal sphincter (LES)

Question 5

Normal fxn of esophagus

Answer 5

1. pharynx contracts; UES relaxes
2. peristaltic wave = synchronous contraction of circular and longitudinal m.
3. bolus approaches LES, LES relaxes for 1-3 secs
4. bolus enters stomach
5. peristalsis is complete, LES returns to basal tone

Question 6

Types of esophageal dysfxn

Answer 6

• motility problems: enteric nervous system vs. musculature ==>
  
  • esophageal dysphagia
  • odynophagia (pain @ throat/neck)
  • chest pain
  • GERD sx
• structural disorders = mechanical or physical defects in esophageal wall ==>
  
  • esophageal dysphagia
  • odynophagia

Question 7

Diagnostic techniques for esophageal dysfxn

Answer 7

• motility problems
  
  • barium swallow = initial assesment
  • esophageal manometry
  • 24hr pH testing
• structural problems
  
  • upper endoscopy (esophagastroduodenoscopy or EGD)
  • biopsy if necessary

Question 8

Examples of esophageal motility problems

Answer 8

• achalasia
• systemic neuromuscular disease
  
  • Scleroderma (progressive systemic sclerosis)
• “hyper-motility” disorders
  
  • nutcracker/jackhammer esophagus
• GERD (gastroesophageal reflux disease)

Question 9

Examples of structural disorders of esophagus

Answer 9

• mucosal inflammation (esophagitis)
• benign or malignant strictures
• Barrett’s (metaplasia) esophagus
• perforation

Question 10

Pathophysiology of GERD

Answer 10

• disorder of esophageal and gastric motility
• reflux of gastric contents into esophagus, mouth, or airway
• occurs when mechanisms of acid protection/neutralization are overwhelmed by movement or decreased acid clearance, e.g.:
  
  • **transient (innapropriate) LES relaxation
  • decreased esophageal peristalsis
  • delayed gastric emptying
  • hiatial hernia may contribute
• gastric juice damages esophagus (w/out protection due to lack of mucosal layer) via HCl, pepsin, and bile

Question 11

Sx of GERD

Answer 11

• heartburn = burning-type pain @ chest or epigastrium that rises upward
• regurgitation
• epigastric pain/fullness
• hypersalivation
• sour taste
• cough, hoarseness, or wheezing
• sx triggers:
  
  • meals, esp. large or heavy
  • sleep/lying down

Question 12

Dx of GERD

Answer 12

• initial: history + confirmation via trial of PPI (proton-pump inhibitor)
• 24 or 48h ambulatory pH testing
  
  • pH probe @ distal esophagus
  • monitor for probe strapped to belt
  • pt. presses button when has sx
  • pH and sx later compared

Question 13

Pathophysiology of Achalasia

Answer 13

• LES w/abnormally high resting pressure + poor/absent peristalsis @ mid/lower esophagus
• ==> intermittment dysphagia for liquids and solids

Question 14

Sx of achalasia

Answer 14

• intermittent ==> severe to solids and liquids
• weight loss

Question 15

Dx of achalasia

Answer 15

• dilate/tortuos esophagus on CXR, barium swallow, upper endoscopy
• “birds beak” appearance of distal esophagus/LES on barium esophagram
• esophageal manometry
  
  • 1. lack of normal peristalsis in the esophageal body (either absent, spastic or with pan-esophageal pressurization)
  • 2. Impaired post-deglutitive LES relaxation

Question 16

Tx of achalasia

Answer 16

• tx goal is t disrupt LES
• surgical myotomy (Heller’s myotomy)
  
  • surgical incision of LES
• pneumatic dilation
• per-oral endoscopic myotomy (POEM)
  
  • endoscopic incision of LES
• positives of tx: effective tx of achalasia
• negatives of tx: reflux disease

Question 17

Characteristics of Barrett’s esophagus

Answer 17

• = transition from normal squamous epithelium to specialized columnar (intestinal) epithelium due to insult of acid reflex
• usually causes no sx
• can lead to dysplasia (pre-cancerous) or adenocarcinoma
• pts often undergo ablation techniques to reduce risk for these complications

Question 18

Characteristics of major types of esophageal cancer

Answer 18

• squamous cell carcinoma
  
  • arises from stratified squamous epithelium
  • risks: age, smoking, alcohol, achalasia, caustic injury to esophagus
  • sx: dysphagia, weight loss
• adenocarcinoma
  
  • more common
  • occurs in context of Barrett’s esophagus (intestinal metaplasia); glandular cancer
  • risk: obesity, GERD hx
  • sx: dysphagia, weight loss, chest pain/dizzy or fatigue, GI bleed