The superior mesenteric artery syndrome. The disease that isn't, or is it?

Intestinal obstruction of the duodenum by entrapment between the aorta and the superior mesenteric artery (SMA) is an uncommon cause of megaduodenum. Despite many case reports, acceptance of the SMA syndrome as a clinical entity has been controversial on account of its confusion with other causes of megaduodenum. We therefore report a case of SMA syndrome which sharply exemplifies its clinical and anatomic features. The clinical findings are proximal duodenal obstruction with an abrupt cutoff and active peristalsis. The anatomic features of this entity are a narrow angle between the aorta and the SMA, together with high fixation of the duodenum by the ligament of Treitz and/or an anomalous SMA crossing directly over the aorta at its intersection with the duodenum. The SMA syndrome may occur as an acute self-limited event due to a reversible precipitating factor, or as a chronic recurring disorder. The acute form subsides with correction of the specific initiating factor; the chronic form responds favorably to simple surgical mobilization of the duodenum.