Superior mesenteric artery syndrome is a rare digestive system disorder. The superior mesenteric artery provides blood to the small intestine, cecum, and colon. It crosses over the first part of the small intestine, called the duodenum. Symptoms occur when the artery obstructs the duodenum.

Symptoms include:

  • abdominal fullness,
  • bloating after meals,
  • nausea and vomiting of partially digested food, and
  • mid-abdominal “crampy” pain that may be relieved by the prone (lying on the stomach) or knee-chest position.

A number of factors may contribute to the syndrome, including:

  • prolonged bed rest,
  • weight loss,
  • rapid growth,
  • previous abdominal surgery,
  • increased curvature in the lumbar portion of the spin (lordosis),
  • use of body casts, and
  • loss of tone in abdominal wall musculature.

The syndrome has also been reported in conjunction with pancreatitis, peptic ulcer, and other intra-abdominal inflammatory conditions.

Diagnosis

The diagnosis can be challenging because superior mesenteric artery syndrome is uncommon and symptoms can be nonspecific. Tests are done to differentiate the syndrome from other disorders that can cause similar clinical features.

Modern imaging techniques can provide noninvasive and detailed anatomic information that can be used in diagnosing the condition. Superior mesenteric artery syndrome is usually suspected based on signs and symptoms. A diagnosis can be confirmed by imaging studies such as an upper GI series (x-rays of the esophagus, stomach, and duodenum), hypotonic duodenography (an x-ray procedure that produces images of the duodenum), and computed tomography (CT scan).

Treatment

Treatment approaches for superior mesenteric artery syndrome have included small feedings or a liquid diet.  Symptoms usually improve after restoration of lost weight or removal of a body cast.

The treatment  typically focuses on addressing the underlying cause of the condition. For example, symptoms often improve after lost weight is restored or a body cast is removed. Nasogastric decompression (a tube passed through the nose into the stomach) and proper positioning after eating (such as lying in the left side or standing or sitting with a knee-to-chest position) may be recommended to alleviate symptoms.

In severe cases, intravenous (IV) nutritional support and/or a feeding tube may be needed to provide enough calories. Affected people can usually then be started on oral liquids, followed by slow and gradual introduction of small and frequent soft meals as tolerated. Then, regular solid foods may be introduced.

Surgery is rarely necessary but may be needed if other treatment strategies do not work. However, other treatment options should usually be tried for at least 4-6 weeks before considering surgery.

Superior mesenteric artery syndrome may be referred to at SMA Syndrome or as SMAS, and by a variety of other names including Cast syndrome, Wilkie syndrome, arteriomesenteric duodenal obstruction, and chronic duodenal ileus.

For More Information and Resources Relating to SMA Syndrome

Medscape Reference (free registration required)

Primary Sources: National Institutes of Health (NIH), Genetic and Rare Diseases Information Center. (NIH webpage accessed December 13, 2016.)

Uptodate.com. Superior mesenteric artery syndrome. (Webpage accessed December 13, 2016.)

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