Superior Mesenteric Artery Syndrome: A Rare Cause of Abdominal Pain

Abstract

Introduction: Superior Mesenteric Artery Syndrome (SMAS) is an extremely rare, potentially life threatening cause of abdominal pain. First described in 1842, it has an incidence of < 0.3% in the general population with a mortality rate as high as 33%. It is caused by reduced mesenteric fat which leads to a decreased angle between the SMA and aorta, resulting in extrinsic compression of the third portion of the duodenum. Most common symptoms include abdominal distension, pain, nausea, vomiting, and weight loss. This case highlights the importance of considering the diagnosis of SMAS in a young, otherwise healthy patient presenting with postprandial vomiting, weight loss, and abdominal pain. Case Report: 22 year old female with no past medical history presented to the emergency department with vaguely localized, sudden onset abdominal pain and vomiting. On review of systems, she reported a five pound weight loss in the last several months that she attributed to poor eating habits and stress due to school. On physical exam, patients was tachycardic. Abdominal exam was significant for moderate epigastric and right upper quadrant abdominal tenderness with voluntary guarding. Laboratories were within normal limits. Computerized tomography of the abdomen and pelvis revealed a dilated mid third portion of the duodenum with a transition point as it passed between the superior mesenteric artery and aorta (Figure 1). This was highly suggestive of SMAS. Patient was treated with conservative management including nutritional support (enterally) resulting in improvement of the patient's symptoms.Figure: CT showing compression of the third part of the duodenum (arrow) between the superior mesenteric artery and the aorta, with consequent upstream dilatation (asterisk).Discussion: In this case, the diagnosis of SMAS was straight forward as the patient's CT imaging of the abdomen and pelvis done in the ED were highly suggestive of the diagnosis. Yet, CT imaging may not always be as supportive of the diagnosis as seen here, necessitating additional work up (further imaging, EGD). The majority of SMAS cases documented in the medical literature usually describe a period of weight loss, either unintentional or intentional, prior to the onset of symptoms, which was demonstrated in this case presentation. It is equally important to recognize the psychological factors that may be involved in SMAS as its association with eating disorders and drug abuse is well documented.