The oesophagus is a muscular tube, approximately 25 em long, connecting the pharynx to the stomach. The muscle coat has two layers-an outer longitudinal layer and an inner circular layer of fibres. In the upper portion both muscle layers are striated. They gradually change to smooth muscle in the lower oesophagus, where they are continuous with the muscle layer of the stomach. The oesophagus is lined by stratified squamous epithelium, except near the gastro-oesophageal junction where columnar epithelium is found.
The oesophagus is separated from the pharynx by the upper oesophageal sphincter, which is normally closed by the continuous contraction of cricopharyngeus muscle.
The lower oesophageal sphincter (LOS) consists of an area of the distal end of the oesophagus that has a high resting tone and is largely responsible for the prevention of reflux. The reduction in tone and relaxation that occurs with swallowing is under the control of nervous (vagal) and hormonal mechanisms.
During swallowing, the bolus of food is moved from the mouth to the pharynx voluntarily. Immediately, the upper sphincter relaxes and food enters the oesophagus. A primary peristaltic wave starts in the pharynx at the onset of swallowing and sweeps down the whole oesophagus . Secondary peristalsis occurs locally in response to direct stimulation (e.g. distension by the bolus) and helps to clear food residue from the oesophagus Non-peristaltic, non-propulsive tertiary waves are frequent in the elderly. The LOS relaxes when swallowing is initiated, before the arrival of the peristaltic wave.
SYMPTOMS OF OESOPHAGEAL DISORDERS
Major oesophageal symptoms are:
• Painful swallowing
This is either due to a local lesion or is part of a generalized disease. Patients will complain of something sticking in their throat or chest during swallowing or immediately afterwards. It is always a serious symptom and the cause must be found. The causes are shown in ; benign and malignant oesophageal strictures are the commonest causes seen in hospital practice. Globus hystericus is the name given to apparent dysphagiathe sensation of a ‘lump in the throat’ in patients who do not have true dysphagia and can therefore swallow. It has no organic cause and the treatment is reassurance.
Heartburn is a common symptom of acid reflux. The pain can spread to the neck, across the chest, and can be difficult to distinguish from the pain of ischaemic heart disease. It can also occur at night when the patient lies flat or after bending or stooping. Hot drinks and alcohol often precipitate the pain.
Painful swallowing without real difficulty is a symptom of candidiasis and herpes simplex infection. Both these conditions are seen in AIDS patients. Ingestion of tablets such as emepronium and potassium (slow release) will produce local ulceration if they lodge in the gullet when swallowed lying down and without water.
SIGNS OF OESOPHAGEAL DISORDERS
There are very few signs associated with oesophageal disease, the main one being of weight loss as a consequence of dysphagia.
INVESTIGATION OF OESOPHAGEAL DISORDERS
BARIUM SWALLOWAND MEAL
MANOMETRY, which is performed by passing a fluidfilled catheter through the nose into the oesophagus. Changes in pressure are transmitted up the fluid column and recorded. These studies are useful in motility disorders.
BERNSTEIN r ss r-c alternate dilute acid and alkali is infused into the oesophagus via a nasal tube to try to reproduce or relieve oesophageal pain. A positive test suggests oesophagi tis but there are many false negatives. pH MONITORING-24-hour monitoring using a pHsensitive probe positioned in the lower oesophagus is being used increasingly for the identification of reflux episodes (pH <4). Brief episodes can, however, occur in normal subjects.
RADIOISOTOPE STUDIES with technetium sulphur colloid incorporated into food can also be used to study reflux. It is not widely used in the UK.