Superior Mesenteric Artery Syndrome: A Vicious Cycle?

Abstract

CASE REPORT Superior mesenteric artery syndrome (SMAS) is a rare syndrome where the third part of the duodenum is compressed between the abdominal aorta and the superior mesenteric artery (SMA).1 The loss of the intervening mesenteric fat pad causes the aortomesenteric angle to decrease from its normal value of 38°–65° to less than 25°, decreasing the aortomesenteric distance to less than 10 mm and causing duodenal compression. Its incidence in the general population is between 0.1% and 0.3% with a female predominance.2 A 22-year-old woman presented to the emergency department of our hospital with complaints of vomiting and a marked decrease in appetite for the past 4 months. The vomiting was nonbilious and nonprojectile and would only occur postprandially. She also reported past episodes of watery diarrhea associated with anorexia and experienced intermittent episodes of fever, documented at 101°F–102°F. Since the start of her symptoms, she had lost 27 kg. An upper abdominal computed tomography scan in both plain and contrast films revealed significant gastric distention, distention of the duodenum up to the second and third parts, and a relatively collapsed small bowel distal to the presumed crossing of SMA (Figure 1). The computed tomography scan displayed downward inclination of SMA and significant compression of the left renal vein between the abdominal aorta and SMA, confirming the existence of left renal vein entrapment syndrome in our case (Figure 2). In addition, there was a reduced aortomesenteric angle of 11.8°, and a distance of 8 mm was observed (Figure 3). In lieu of the above findings, SMAS was suspected. The patient initially received conservative treatment and was started on nasogastric feeding tube. Owing to intolerance, a total parenteral nutrition regimen was used to stabilize the patient's weight. Only 2 kg were gained by the patient over the course of 4 weeks. Her symptoms continued to worsen despite her slight weight gain. Having failed to achieve a satisfactory outcome with conservative management, an exploratory laparotomy was performed. The peritoneal cavity was exposed through a midline skin incision. There was gross distention of the second part of the duodenum, and the third part of the duodenum was compressed. Owing to grossly dilated duodenum, the decision was taken to perform gastrojejunostomy instead of duodenojejunostomy. Stapled posterior gastrojejunostomy was performed to bypass the compressed duodenum, and an anastomosis was made between the stomach and the proximal loop of the jejunum (Figure 4). The intraperitoneal drain was kept in place. An uneventful recovery followed the patient's extubation.Figure 1.: Computed tomography scan showing compression of the third part of the duodenum. Arrow is pointing toward the compressed duodenum.Figure 2.: Computed tomography scan showing compression of the left renal vein. Arrow is pointing towards the compressed left renal vein.Figure 3.: Computed tomography scan showing compression of the third part of the duodenum. Angle denoting a reduced aortomesenteric angle value of 11° (normally>38°).Figure 4.: Computed tomography scan after gastrojejunostomy displaying the anastomosis made between the stomach and the proximal loop of the jejunum. Arrow pointing towards the anastomotic site.This case report presents an early preoperative diagnosis of a rare disease entity based on its radiological presentations. When women with a low body mass index present with chronic, refractory symptoms of the upper digestive system, SMAS should be suspected. It can also often be confused with other etiologies of mega duodenum such as diabetes mellitus, systemic lupus erythematosus, amyloidosis, myotonic dystrophy, scleroderma, and chronic idiopathic intestinal pseudo-obstruction. This necessitates the need of a multidisciplinary approach based on symptoms to diagnose SMAS by clinicians. DISCLOSURES Author contributions: A. Jawed collected patient information and followed up after discharge and wrote the manuscript. A. Jawed wrote the manuscript. ME Anis identified the case and treated the patient, revised the manuscript, and is the article guarantor. MA Qadeer and Z. Abbas revised the manuscript. Financial disclosure: None to report. Informed consent was obtained for this case report.