From the Guidelines
Superior Mesenteric Artery (SMA) syndrome is a condition characterized by insufficient vascular supply to the small bowel, often caused by compression of the SMA by the median arcuate ligament (MAL) or other anatomical structures.
Causes and Presentation
- The causes of mesenteric ischemia, including SMA syndrome, can be broadly divided into:
- Mesenteric arterial occlusion, including atherosclerotic disease, anatomical causes such as MAL syndrome, thromboembolism, and vasospasm
- Mesenteric venous occlusion
- Global hypoperfusion, including hypotension and shock
- Patients with SMA syndrome typically present with:
- Insidious onset of postprandial pain
- Fear of eating
- Weight loss
Diagnosis and Imaging
- CT of the abdomen and pelvis should be performed in the non-contrast, arterial and portal venous phases to identify the underlying cause of ischemia, evaluate for possible bowel complications, and exclude other potential diagnoses of acute abdominal pain 1
- MR angiography (MRA) can also be considered, but is limited in its ability to evaluate for ischemic bowel changes compared to CT
Treatment and Intervention
- Intervention is targeted at rapid revascularization, and the preferred modality of intervention depends on chronicity, etiology, and degree of concern for bowel infarction
- Imaging is helpful in evaluating the target vessels for revascularization, the nature and degree of stenosis/occlusion, and possible approaches to arterial access 1
From the Research
Definition and Causes of Superior Mesenteric Artery (SMA) Syndrome
- Superior Mesenteric Artery (SMA) syndrome is a rare condition of duodenal obstruction, caused by the overlying SMA 2.
- It is characterized by compression of the third part of the duodenum as it passes beneath the proximal superior mesenteric artery, leading to postprandial epigastric pain, vomiting, and weight loss 3.
- The syndrome may be precipitated by sudden weight loss secondary to other pathologies, such as trauma, malignancy, or eating disorders 3.
Clinical Manifestations and Diagnosis
- The clinical manifestations of SMA syndrome include abdominal pain, vomiting, and weight loss, which are shared with many other disease entities 2.
- Diagnosis is confirmed by radiological investigations, such as angiography, which reveals a reduced aorto-SMA angle and distance, and contrast studies showing duodenal obstruction 3.
- Other diagnostic tools, including endoscopy, ultrasound imaging, and tomography, may also be used to assist in diagnosis 4.
Treatment and Management
- Conservative management aims to increase intra-abdominal fat by dietary manipulation and thereby increase the angle between the SMA and aorta 3.
- Surgical procedures, such as laparoscopic duodenojejunostomy, may be indicated in cases where conservative management fails or symptoms are severe 3, 5.
- A multi-speciality team approach, including gastrointestinal, vascular, and radiological specialists, is recommended for the management of SMA syndrome 3.