Pathophysiology of the Esophagus Flashcards Preview

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Flashcards in Pathophysiology of the Esophagus Deck (18):
1

Characteristics of oral phase of swallowing

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

2

Characteristics of pharyngeal phase of swallowing

  • 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. 

3

Types of oropharyngeal disease

  • 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

4

Anatomy of the esophagus

  • 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)

5

Normal fxn of esophagus

  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

6

Types of esophageal dysfxn

  • 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

7

Diagnostic techniques for esophageal dysfxn

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

8

Examples of esophageal motility problems

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

9

Examples of structural disorders of esophagus

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

10

Pathophysiology of GERD

  • 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

11

Sx of GERD

  • 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

12

Dx of GERD

  • 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

13

Pathophysiology of Achalasia

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

14

Sx of achalasia

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

15

Dx of achalasia

  • 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

16

Tx of achalasia

  • 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

17

Characteristics of Barrett's esophagus

  • = 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

18

Characteristics of major types of esophageal cancer

  • 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