Extrinsic compression of the third portion of the duodenum was well-described by Rokitansky in 1861. Since that time there have been numerous case reports of this syndrome, often referred to as the superior mesenteric artery (SMA) syndrome. The patients who develop this form of external duodenal compression fall into several broad etiologic categories: (1) congenital; (2) rapid weight loss; (3) rapid growth without weight gain; and (4) hyperextension of the spine in a cast or brace.
The congenital cases involve minor abnormalities of embryonic duodenal rotation and fixation1.2 and will not be considered in this discussion of SMA syndrome.
Much of the confusion that exists about the SMA syndrome results from the vagaries of the symptoms and roentgenographic findings that it produces. It has also often been confused in the literature with the syndrome produced by partial occlusion of the SMA with resultant vascular insufficiency of the small bowel;