Radiologic amyl nitrite test for distinguishing pseudoachalasia from idiopathic achalasia.

In a simple radiologic test, amyl nitrite inhalation seems to distinguish patients with pseudoachalasia from those with idiopathic achalasia. In three pseudoachalasia patients with tumor infiltration of the distal esophagus, the narrow lower esophageal sphincter segment was unaffected by the smooth-muscle relaxant effect of amyl nitrite. In contrast, amyl nitrite caused a measurable increase of 2 mm or more in sphincter diameter in nine patients with idiopathic achalasia. The amyl nitrite test may be a useful method for distinguishing patients with pseudoachalasia from those with idiopathic achalasia.