Does the position of the patient (upright or prone) affect the outcome of the radiological examination ?
E. Lafontaine, A.C. Duranceau, C. Deschamps (Montreal)
Effective radiographic evaluation of the esophagus requires the use of a combination of different techniques. Each technique and position of the patient has its advantages and limitations in the detection of structural and motility disorders. Radiographic evaluation of a motility disorder includes examination of the esophageal body and both the upper and lower esophageal sphincters. Fluoroscopic observation is usually adequate to evaluate motor function of the esophageal body. Cine techniques are usually necessary in the assessment of oropharyngeal function because of the rapidity of deglutitive events in this area.
The radiologic examination is done with low density barium at room temperature. Cold barium decreases the frequency and amplitude of peristaltic waves in response to deglutition. This spasmolytic effect of cold barium results in better distension of the esophagus and may be used to better demonstrate structural abnormalities . Every swallow is observed separately until the bolus has reached the stomach. Continuous drinking is only of use if one wishes to achieve maximal distension of the esophagus for demonstrating structural abnormalities, such as a web for example. Several successive isolated swallows must be observed. In the incipient stages of this disease the normal pattern of primary peristalsis may be altered only intermittently.
A complete examination uses both the upright and prone position [2, 3]. Peristaltic activity of the entire esophageal body is better assessed in the prone position. In the upright position, esophageal emptying is affected by gravity. In this position the swallowed bolus passes rapidly in the distal esophagus. However, it is the physiological position in which the symptoms of a motility disorder manifest themselves and a thorough assessment of esophageal function must include this
position. It gives a better anatomical appearance of the lower esophageal sphincter, the amount of stasis at this level and the height of the barium column needed to induce opening of this sphincter. The importance of esophageal distension is also well demonstrated.
These radiological details are necessary at times to differentiate for instance vigorous achalasia from diffuse esophageal spasm. They may present with similar abnormalities of the esophageal body whereas in diffuse esophageal spasm the function of the lower esophageal sphincter is essentially normal.
Assessment of esophageal motor function is completed in the prone position. The neutralization of gravity permits better observation of the motility of the entire esophageal body. The normal sequence of a primary peristaltic wave is seen as an aboral contraction wave that obliterates the esophageal lumen and gradually propulses the barium bolus from the esophagus into the stomach.
Diffuse esophageal spasm is an uncommon primary esophageal motor disorder. In response to a barium swallow peristalsis is intermittently disrupted in the smooth muscle portion of the esophagus where nonperistaltic contractions replace the disrupted primary wave. Spontaneous, obliterating contractions may also occur (figure 1). This results in the typical corkscrew appearance. The lower esophageal sphincter functions normally.
Ott et al. reported the correlation between manometry and radiology in the assessment of dysphagia secondary to an esophageal motor disorder. The sensitivity
Figure 1. Barium esophagram shows diffuse esophageal spasm. There is intermittent disruption of primary peristalsis associated with simultaneous tertiary contractions.
of the radiological examination to detect a motor disorder varied according to the underlying disorder. Compared with manometry, radiographic sensitivities were 95 p. cent for achalasia and 71 p. cent for diffuse esophageal spasm .
The radiological examination of diffuse esophageal spasm requires that the study be done in both the upright and prone positions. Certain functional details of the esophagus are better observed in the upright position. The prone position gives a better evaluation of the motility of the whole esophagus.