Superior mesenteric artery syndrome

A rare digestive system disorder

SMA syndrome

Superior mesenteric artery syndrome (SMAS) is a rare, potentially life-threatening gastrointestinal disorder characterized by the compression of the duodenum between the abdominal aorta and the superior mesenteric artery (SMA). This condition leads to partial or complete blockage of the duodenum, resulting in a variety of gastrointestinal symptoms.

Pathophysiology

The superior mesenteric artery arises from the anterior surface of the abdominal aorta and supplies blood to a large portion of the intestines. In SMAS, the angle between the SMA and the aorta is reduced, typically to less than 25 degrees, compared to the normal range of 38-56 degrees. This narrowing can compress the third part of the duodenum, leading to obstruction.

Causes

SMAS can be caused by any condition that results in a loss of the mesenteric fat pad, which normally acts as a cushion between the SMA and the duodenum. Common causes include:

• Significant weight loss due to anorexia nervosa, malignancy, or malabsorption syndromes.
• Congenital anatomical abnormalities.
• Surgical procedures that alter the position of the SMA or duodenum.

Symptoms

The symptoms of SMAS can vary in severity and may include:

• Severe abdominal pain
• Nausea and vomiting
• Early satiety
• Bloating
• Weight loss
• Postprandial fullness

Diagnosis

Diagnosis of SMAS is often challenging due to its rarity and the nonspecific nature of its symptoms. It typically involves:

• Upper gastrointestinal series
• Computed tomography (CT) scan
• Magnetic resonance imaging (MRI)
• Doppler ultrasound to assess blood flow and the angle between the SMA and aorta.

Treatment

Treatment of SMAS focuses on relieving the duodenal obstruction and addressing the underlying cause. Options include:

• Nutritional support to restore weight and the mesenteric fat pad.
• Postural therapy, such as lying in the left lateral decubitus or prone position to relieve compression.
• Surgical intervention, such as duodenojejunostomy or gastrojejunostomy, in severe cases where conservative measures fail.

Prognosis

The prognosis for SMAS varies depending on the severity of the condition and the success of treatment. With appropriate management, many patients experience significant improvement in symptoms.

Related pages

• Duodenum
• Abdominal aorta
• Superior mesenteric artery
• Gastrointestinal tract

External links

Classification
External resources	eMedicine: article/932220

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