Cast Syndrome or Superior Mesenteric Artery syndrome

Cast syndrome is also known as superior mesenteric artery syndrome. It is an uncommon complication in the treatment of orthopedic conditions. It results from obstruction of the third portion of the duodenum by superior mesenteric artery leading to high intestinal obstruction.

It should be kept in mind that this obstruction can occur in absence of plaster also because there are many causes to mesenteric artery obstruction.

Cause of Cast Syndrome

Most cases involve young adults with more than half of these cases have patients with scoliosis or kyphosis or treatment of hip conditions.  It has been seen after casting with body jackets, shoulder spicas, and hip spicas where the common denominator is extensive coverage of the abdomen and chest.

The problem usually is located at the junction of the third and fourth parts of the duodenum, where the duodenum is bound by the ligament of Treitz. The duodenum passes across the anterior aspect of the lumbar spine from right to left at the level of the first and second lumbar vertebrae. Just above this point, the superior mesenteric artery arises from the abdominal aorta and passes downward with its accompanying veins in the mesentery.

There is the potential for compression of the third portion of the duodenum between lumbar spine and aorta posteriorly and the mesentery and vessels anteriorly.

Two contributing factors are recumbency, which causes the weight of the mesentery to lie against the duodenum, and increased lumbar lordosis, which tends to displace the duodenum anteriorly.

Gastric distention may aggravate the situation by forcing the remainder of the abdominal contents more distally and stretching the mesenteric vessels further.

Clinical Presentation

The signs and symptoms of cast syndrome are typical of upper intestinal obstruction. They may come on insidiously or after several weeks after cast application or surgery.

The initial symptom is a feeling of fullness followed by nausea and vomiting.

Abdominal distention is obscured in the presence of a body jacket. Vomiting, which may be intermittent in the early stages, becomes pernicious, with dehydration and metabolic alkalosis. Progressive metabolic derangement, oliguria, and shock may occur.

When these signs and symptoms occur in a patient who is in a body cast or who has had spinal trauma (including surgery), the diagnosis should be suspected.

Xrays of the abdomen may show early gastric dilatation.  Contrast may help to reveal the distention of the stomach and the proximal portion of the duodenum. Usually, there is a  sharp cutoff pattern at the region where the arteriomesenteric pedicle crosses the duodenum.  Xrays help to differentiate this syndrome from cholelithiasis, pancreatitis, gastric or duodenal ulcer, and high intestinal obstruction.

Treatment of Cast Syndrome

• Removal of the offending plaster if any
• The absolute dietary restriction should be imposed, supplemented by nasogastric suction.
• Intravenous fluids are essential to maintain hydration and to correct any electrolyte or acid-base abnormalities.
• Positioning the patient on the left side or prone relieves some of the effects of gravity in pulling the mesenteric pedicle against the duodenum. With the patient prone, tipping the bed to tilt the head down further decreases pressure from the pedicle.
• If these conservative measures are not sufficient to reverse the process, the treatment of choice is surgery duodenojejunostomy or gastrojejunostomy.

Prevention

Cast syndrome may be prevented by avoiding constrictive body casts that accentuate lumbar lordosis or prevent normal changes in abdominal contour. Patients at risk should be turned frequently or encouraged to move from side to side.