Oesophageal disease Flashcards
1
Q
List the causes of acquired megaoesophagus
A
- chronic/recurrent oesophageal obstruction
- extra-oesophageal obstruction eg. tumours, abscesses, pleuropneumonia, vascular ring anomalies
- neurologic disorders eg. diseases that cause vagal neuropathy (EPM, EHV myeloencephalitis, idiopathic vagal neuropathy)
- neuromuscular disorders eg. equine dysautonomia (botulism)
- alpha-2 agonists (detmoidine) - transient and reversible
- genetic predisposition eg. Friesians (recessive inheritance)
- reflux oesophagitis (cause or effect?)
2
Q
List the causes of oesophageal stricture
A
- pressure necrosis from oesophageal impactions that induce circumferential erosion or ulceration of the oesophageal mucosa
- oesophageal injury caused by oral administration of corrosive medicinal agents
- trauma to the neck
- congenital
3
Q
List the types of oesophageal stricture
A
- Oesophageal web or ring: stricture caused by mucosal and submucosal trauma
- Mural stricture: originating in muscular layers and adventitia of the oesophagus
- Annular stenosis: stricture originating in all layers of the oesophagus
4
Q
How are oesophageal strictures diagnosed?
A
- Endoscopy can be used to detect oesophageal webs or rings
- Identification of mural strictures or annular stenosis may require a double-contrast oesophagram
5
Q
What is the treatment for oesophageal strictures
A
- Conservative management - slurry diet, anti-inflammatories, antimicrobials; allow 60 days
- bougienage and balloon dilation
- surgery: resection and anastomosis, temporary oesophagostomy with fenestration of the stricture, oesophagomyotomy (for strictures of muscularis and adventitia), patch grafting with local musculature —-> high complication rates with surgery.
6
Q
Describe the two types of oesophageal diverticula
A
- Traction (true) diverticula: result from wounding and subsequent contraction of perioesophageal tissues with resulting tenting of the wall of the oesophagus; appear as dilation with a broad neck on contrast oesophagography; usually asymptomatic
- Pulsion (false) diverticula: arise from protrusion of oesophageal mucosa through defects in the muscular wall; usually result from trauma or acute changes in intraluminal pressure; flask shape with a small neck on an oesophagram; can fill with feed material, ultimately leading to oesophageal obstruction and rupture; can be corrected surgically by inverting or resecting prolapsed mucosa and closing defect in wall
7
Q
List congenital disorders of the oesophagus
A
- congenital stenosis
- persistent right aortic arch and other vascular anomalies
- oesophageal duplication cysts
- intramural inclusion cysts
- idiopathic megaoesophagus
8
Q
Describe the muscle types in the oesophagus and their innervation
A
- a transition occurs in the muscle type composing the tunica muscularis:
proximal two thirds = striated skeletal muscle; motor innervation includes pharyngeal and oesophageal branches of vagus n.
distal third = smooth muscle; parasympathetic fibres of the vagus n. supply the smooth muscle - sympathetic innervation of the oesophagus is minimal
9
Q
Describe the function of the lower oesophageal sphincter
A
- relaxation of the lower oesophageal sphincter permits passage of ingested material from oesophagus to stomach
- distension of stomach with ingesta mechanically constricts lower oesophageal sphincter
- gastric distension also triggers a vagal reflex that increases lower oesophageal sphincter tone, a safety mechanism against gastro-oesophageal reflux
- the mechanical and vagal mechanisms that promote lower oesophageal sphincter tone prevent spontaneous decompression of the stomach, which, along with lack of vomiting reflex in the horse, increases the risk of gastric rupture during episdoes of severe distension
10
Q
List the causes of primary oesophageal obstruction
A
- impactions of roughage
- prior oesophageal trauma or poor mastication (dental abnormalities)
- wolfing or gulping food; if exhausted or mildly dehydrated after long ride or weakened from chronic debilitation
11
Q
List the causes of secondary oesophageal impaction
A
- disorders that physically impede passage of food material and fluid by narrowing luminal diameter, reduce the compliance of the oesophageal wall or alter conformation of oesophageal wall (food material may accumulate in pocket or diverticulum)
- foreign bodies
- intramural (tumours esp SCC, strictures, diverticula, cysts) or extramural (mediastinal or cervical masses) masses
- acquired or congential anomalies
12
Q
List the clinical signs of oesophageal obstruction
A
- related to dysphagia
- anxious, stand with neck extended
- gagging or retching
- bilateral frothy nasal discharge containing saliva, water, food
- coughing
- odynophagia
- ptyalism
- other signs include dehydration, electrolyte or acid-base imbalances, weight loss, aspiration pneumonia
13
Q
Where are the most common locations for oesophageal obstruction?
A
- sites of natural narrowing of oesophageal lumen eg. cervical oesophagus, thoracic inlet, base of the heart or terminal oesophagus
14
Q
List the diagnostic techniques for oesophageal obstruction
A
- endoscopy is most direct method for diagnosis and also useful for critical diagnostic and prognostic information after resolution (ulceration, rupture, masses, strictures, diverticula, signs of functional abnormalities)
- passage of NGT
- ultrasonography
- radiography +/- air or barium contrast studies for evaluation after relief of obstruction if stricture is suspected
15
Q
List the important sequelae to oesophageal obstruction that may predispose to re-obstruction
A
- dilation proximal to site of obstruction
- mucosal injury from trauma
- stricture formation
- formation of a diverticulum
- megaoesophagus
- oesophagitis
- underlying functional or morphological abnormalities much more likely in recurrent cases
