Oesophagus
Structure and Function
Structure
The oesophagus is a collapsible, tubular structure about 10 inches long that connects the pharynx to the stomach. It joins the pharynx at the sixth cervical vertebra and the diaphragm at the tenth thoracic vertebra.
It runs down parallel to the larynx/trachea, and is narrowed at three sites, behind the cricoid cartilage of the larynx, where the left bronchus and the arch of the aorta cross the front of the oesophagus and where the oesophagus enters the stomach.
Functions:
The main use is so that a bolus of food can travel down to the stomach. It does this through waves of contractions called peristalsis. There is a small amount of secretion in the oesophagus, but its basically all about moving stuff to the stomach.
Arterial and Venous supply
Nervous Supply
It is supplied by both sympathetic and parasympathetic efferent and afferent fibres via the vagi and sympathetic trunks. At the lower end it is surrounded by the oesophageal nerve plexus.
Lymph
Upper third: the deep cervical nodes (like the pharynx). Middle third into the superior and posterior mediastinal nodes, and from the lower third into nodes along the left gastric blood vessels and the celiac nodes.
Histology
Like the pharynx, it is lined with non keratinising stratified squamous epithelium. The submucosa has mucous glands (that secrete acid mucins), lymphoid aggregations, and has prominent blood vessels, especially at the stomach end. The muscle is striated in the upper third, mixed in the middle, and smooth in the lower third.
Its important to remember the oesophagogastric junction, as it's a big pathogenic place. The last 1.5cm of the oesophagus is lined by columnar epithelium, and there are many conditions that result from exposure of the squamous epithelium of the lower oesophagus to stomach acid and enzymes – such as ulcers, strictures (narrowing) and cancer.
Clinical Conditions
There are some common diagnoses of oesophageal symptoms:
- Dysphagia – always a serious symptom, most commonly benign and malignant strictures.
- Substernal pain/Heartburn – acid reflux
- Acid regurgitation - GORD
- Painful swallowing – without any real difficulty this can be a sign of candidiasis
Achalasia
About: Usually seen in elderly. It's a tapering of the oesophagus due to degeneration of the parasympathetic plexus (Auerbach's plexus). Leads to proximal dilatation (it swells up around the blockage) which increases risk of GORD. Increased risk of Barrett's (10%) and adenocarcinoma (5%). Basically, peristalsis doesn't work properly because the muscle is not working properly, and the LOS won't relax properly, causing a tapering. If you hear stricture or distal narrowing that isn't cancer, this is probably the one.
Symptoms: Dysphagia, regurgitation of undigested food, coughing (esp. at night or lying down), heartburn, and chest pains after eating.
Treatment: Inject some botox, which puts it all in spasm. Not permanent, symptoms return within a year.
Barret's Oesophagus
Lower oesophageal metaplasia, where the squamous cells become columnar. May convert to colonic or gastric cells – the colonic ones have a higher adenocarcinoma rate. It is considered a "premalignant" condition – one to be alert for. 10% of patients presenting with GO reflux have it.
Candidiasis
Basically thrush, down the throat. Usually seen only in immuno compromised patients – so basically, if a 25 year old guy comes to you with this, he probably has AIDS. Treat with Fluconazole, but if there is an underlying immunosuppression, that must be treated too.
Carcinoma
About: 90% are squamous cell carcinomas, which occur in the upper or middle third. 8% are adenocarcinomas, in the lower third.
Risks:
- Squamous: alcohol/tobacco, coeliac disease.
- Adenocarcinoma: 15% associated with Barrett's.
Symptoms: Progressive dysphagia, respiratory symptoms due to overspill, or sometimes a trachea-oesophageal fistula and that old cancer stand by – weight loss.
Survival: Overall 20% 5 year survival, very low. Only 40% operable.
Foreign body
Look out for children for this one, with stridor and bleeding. More of a tracheal one usually.
GORD
About: Reflux of stomach contents into oesophagus, as far as the mouth. Commonly causes strictures (due to scarring), and can lead to Barrett's, ulcers, and even cancer.
Symptoms: Major symptom is heartburn, a burning discomfort behind the breastbone. There will be oesophagitis, often with dysphagia.
Treatment:Avoid aggravating factors, with head raised in sleep. Drugs such as Proton Pump Inhibitors and H2 receptor blockers reduce gastric secretion of acid, and relieve complaints in most sufferers.
Malorie-Weiss Tear
Upper Oesophageal sphincter tears due to excess vomiting.
Varices
About: This happens when the portal vein becomes blocked (often happens in liver cirrhosis, in two thirds of cirrhotic patients). So if the person is an alcoholic, this is probably the one. The blood is shunted from the protosystemic system to the veins that congregate around the oesophagus. They dilate and protrude into the lumen, where they are traumatised by passing food. Haemorrhage is common, and causes sever haematemesis (vomiting of blood). In 40% of cases this is fatal.
Treatment:A Sengstaken-Blakemore balloon (like we'll remember that). It's basically a double balloon, one in the stomach, to anchor it to the GO junction, and one in the oesophagus to apply pressure against the veins and stop bleeding.