Diseases of the Esophagus Flashcards
What is the main physiological function of the digestive tract?
To process acquired food and water to meet the nutritional needs of the multi cellular organism
What is the single task of the esophagus?
To transport the bolus (food/water) from pharynx into the gastric reservoir (sometimes to transport things out)
How is swallowing both voluntary AND involuntary?
The initial phase is voluntary, but as the bolus is pushed backwards by the tongue to the hypopharynx the involuntary phase of the swallow reflex is triggered
How many muscles are required for swallowing
More than 50 (oral, pharyngeal, laryngeal, esophageal, and diaphragmatic)
What compartments of the body does the esophagus traverse?
Cervical, Thoracic, and Abdominal (It is 18-26 cm in length)
What four layers make up the wall of the esophagus? How thick is each layer?
Mucosa, submucosa, muscularis propria, and adventitia; They each reach 2-4 mm in thickness
What outward motion signifies the start of the involuntary phase of swallowing?
Upward movement of the “adam’s apple”
What is the difference between the inner and outer muscular layer of the esophagus?
Inner layer is circular Outer layer is longitudinal
Which layer of the esophagus is not fixed, and slides over the other layers?
Mucosa layer
What are the muscular differences between the upper esophageal sphincter (UES) and the lower esophageal sphincter (LES)?
The upper quarter of the esophagus and UES are composed of striated muscle The lower half of the esophagus along with the LES are composed of smooth muscle
Which layer of muscle thickens near the LES?
Inner circular layer
What is the crural diaphragm?
Part of the diaphragm around the LES that contributes to the resting tone (also called the external esophageal sphincter)
What is peristalsis?
Coordinated and propulsive sequential contraction of the esophageal muscle
What mechanism allows primary peristalsis to occur?
Appropriately timed relaxation of the upper and lower esophageal sphincters
Describe the two subtypes of peristalsis?
- Primary - triggered by swallow (associated with pharyngeal contraction and UES relaxation)
- Secondary - Triggered by esophageal distention (contraction starts proximal to distention)
What two nervous processes contribute to peristalsis?
Intrinsic: Enteric neural plexus
Extrinsic: Vagus nerve
How is proximal esophageal striated muscle peristalsis controlled?
Action potential involves calcium release mainly from sarcoplasmic reticulum via T-tubules The peristalsis is generated by the swallowing “central pattern generator” of the brainstem
How is distal esophageal smooth muscle peristalsis controlled?
Calcium influx from outside and latency gradiant with “dual peripheral innervation” Peristalsis is physiologically regulated as “a wave of inhibition followed by a wave of excitation”
Vagal efferents synapse both on _______ and ______ myenteric neurons
inhibitory; excitatory
How do vagal efferents affect excitatory motor neurons?
Predominantly acetylcholine (some substance P) leads to calcium release and depolarization and second messenger pathways
How do vagal efferents affect inhibitory motor neurons?
Predominantly NO leads to a cGMP dependent pathway which inhibits calcium entry and leads to hyperpolarization (Can also be triggered by vasoactive intestinal peptide)
Do layers of the esophageal muscles contract separately or together?
Together - they move in a coordinated fashion to propel the bolus
What is the most specific esophageal symptom in esophageal disorders?
Dysphagia (difficulty swallowing)
What kinds of food can lead to dysphagia? Which causes dyphagia first?
Solid AND liquid (Solid food is more dependent on peristalsis and will present first with dysphagia)
What other symptoms often present with dysphagia and can be used to aid in diagnosis?
- Heartburn
- Regurgitation (effortless)
- Odynophagia (pain during swallow and bolus transit)
- Chest pain (Non exertional and non cardiac)
How long after swallowing should pain occur for dysphagia diagnosis?
less than 10 seconds
What are the differences in dysphagia symptoms based on location?
- Esophageal - Sticks or hangs up after swallow; may have chest pain when stuck
- Pharyngeal - Difficulty initating swallow; coughing, choking and nasal regurgitation
What are the common etiologies of dysphagia? (Mechanical vs. Neuromuscular)
- Mechanical:
- Peptic stricture (caused by acid reflux)
- Esophageal ring (acquired or congenital)
- Cancer
- Neuromuscular:
- Achalasia (most important)
- Esophageal spasm; dysmotility (non-specific)
What are some uncommon etiologies of dysphagia? (mechanical vs. neuromuscular)
- Mechanical: Web, diverticulum, tumors, foreign body
- Neuromuscular: Sclerodoerma; Chagas disease; Collagen Vascular disorders
What signs of solid food dysphagia are indicative of cancer? peptic stricture? esophageal rings?
- Cancer: Progressive and age > 50
- Peptic stricture: Chronic heartburn
- Esophageal Ring: Intermittent
What signs of solid OR liquid food dysphagia are indicative of scleroderma/achalasia? spasm?
- Liquid food dysphagia is often neuromuscular
- Scleroderma/Achalasia: Progressive with heartburn/regurgitation
- Spasm: Intermittent and chest pain
What can be done diagnostically to identify esophageal disorders?
- Upper GI endoscopy (structural information
- Esophageal manometry (functional information)
- Radiography: esophagram (structural and functional)
What can you look for during an endoscopy?
- Hypopharynx (observe true and false vocal cords and arytenoids
- LES open or closed?
- Obstruction?
- Is Z line visible?
What is esophageal manometry?
- The technique for measurement of esophageal intra-luminal pressures (gold standard for diagnosis of esophageal motor disorders)
- Time vs. Amplitude of contraction
- How long does the UES relax to allow bolus passage?
- What is the amplitude of the contraction produced by the primary peristaltic wave?
- What is the duration and speed of peristalsis?
- How long does the LES relax to allow bolus emptying into stomach?
- Half a second;
- 150mmHg;
- 3-7 sec at a speed of 3-5 cm/sec;
- relaxes for 3-8 seconds
What two processes make up achalasia?
- Impaired relaxation of the LES and increased LES tone
- Loss of peristalsis in the body of the esophagus
What causes abnormal function of LES In achalasia?
Due to impaired and then loss of inhibitory (NO) activity
What morphology is associated with achalasia?
- Degeneration of ganglion cells in myenteric plexus
- Inflammatory lymphocytic infilatration
How does achalasia present?
- Peak incidence in 7th decade (and 20-30) - Bimodal
- Dysphagia is predominant symptom (solids and liquids)
- Heartburn, chest pain, regurgitation and weight loss
- Food stasis, bacterial fermentation and acidity Accommodative behavior
How many modalities are needed for diagnosis of achalasia?
Two or three (must be observed structurally AND functionally)
What are two different appearances of the barium esophagram that may indicate achalasia?
- Bird beak
- Sigmoid shape
What is the differential diagnosis of achalasia (or what causes secondary achalasia)?
- Malignancy
- Other infiltrative disorders
- Chagas disease
- Para-neoplastic syndromes
- Autonomic nerve damage
What are the three types of therapy for achalasia?
- Pharmacotherapy (NO donors and anticholinergic agents)
- Endoscopic therapy - Botulinum toxin injection or pneumatic dilation
- Operative therapy
What characterizes an esophageal spasm?
Dis-coordinated contraction of the muscularis layer
Why is esophageal spasm an issue?
It interferes with efficient delivery of food and fluids to the stomach
In scleroderma esophagus the esophagus loses much of its ability to ______
contract (complete aperistalsis)
