Bedridden Woman With SMA Syndrome

CLINICAL HISTORY

A 34-yr-old bedridden woman with mental delay, cerebral palsy, and lower extremity paraplegia presented to the emergency department after 10 to 15 episodes of greenish-tinged vomit. Her caregivers reported that the she had been vomiting for the entire day. They noted that her last bowel movement was three days previously. There was no history of fever or recent travel. 

On physical exam, the patient’s abdomen was non-tender, non-distended, and had normal bowel sounds.

Given the patients history, the emergency physician on duty ordered an abdominal radiograph followed by a CT of the abdomen and pelvis with oral and IV contrast to rule out a small bowel obstruction.

FINDINGS

The AP radiograph of the abdomen (Figure 1) demonstrated marked dilatation of the stomach (S) without dilated loops of small bowel. Incidentally seen in the right upper quadrant was a gallstone (GS).
 

(Figure 1)

After the abdominal radiograph, a CT of the abdomen and pelvis with oral and IV contrast was performed.

The scout image (Figure 2) again demonstrated an enlarged stomach (S) and right upper quadrant gallstone (GS).

(Figure 2)

The CT coronal images (Figure 3) demonstrated an enlarged stomach and a dilated loop of proximal duodenum.

(Figure 3)

The CT axial images (Figure 4) demonstrated a dilated stomach and proximal duodenum with abrupt collapse of the duodenum at the site where it crossed posterior to the superior mesenteric artery. 

(Figure 4)

Finally, the sagittal images (Figure 5) from the CT of the abdomen and pelvis with oral and IV contrast demonstrated a superior mesenteric artery to aorta angle measurement of approximately19 degrees (nl 45-60 degrees).

(Figure 5)

Our final impression was that the findings were suggestive of superior mesenteric artery syndrome.

DISCUSSION

SMA syndrome is an obstructive process that occurs when the duodenum becomes compressed as it passes between the aorta and superior mesenteric artery. Symptoms are similar to those seen with proximal small bowel obstruction such as abdominal pain and bilious vomiting, and delayed diagnosis can lead to fatalities due to gastric perforation and electrolyte abnormalities.

The cause of SMA syndrome is thought to be due to narrowing of the angle between the superior mesenteric artery and the aorta, which is often the result of loss of surrounding mesenteric fat.

Consequently, bedridden patients are commonly affected and associations with conditions with rapid weight loss like anorexia nervosa, trauma or burns, spinal cord injury and paraplegia, and prolonged bed rest have also been suggested.

Imaging should start with an abdominal radiograph, which may demonstrate gastric distention and dilation of the proximal duodenum. Additional imaging can be done with an Upper Gastrointestinal Series or CT scan to demonstrate dilatation of the proximal portion of the duodenum and site of transition at the superior mesenteric artery. A CT scan also allows for measurement of the SMA to aorta angle. A normal SMA to aorta angle measures approximately 45 to 60 degrees. It has been reported that in SMA syndrome, the angle can be reduced to less than 10 degrees.

The emergent treatment of SMA syndrome is decompression of the obstruction via a nasogastric tube and correction of fluid and electrolyte abnormalities. Definitive treatment is focused on reversing the precipitating factor. In cases of weight loss, nutritional support is necessary. If conservative management is not effective, surgery is usually required to reposition the duodenum.

FOLLOW-UP

In the case described, the patient was thin and bedridden as result of lower extremity paraplegia. These characteristics likely increased her chances of developing SMA syndrome. Ultimately, she had multiple obstructive recurrences and required surgical treatment.

Case submitteed by Vinh Q. Phan, MD, Department of Radiology, Staten Island University Hospital, New York, NY.