Makindo Medical Notes

Normally, fat and lymphatic tissues around the SMA provide protection to the duodenum against compression.

About

• A rare acquired disorder first described by von Rokitanski in 1861.

Aetiology

• Superior mesenteric artery (SMA) syndrome is a rare acquired disorder
• Acute angulation of SMA causes compression of the third part of the duodenum between the SMA and the aorta, leading to obstruction
• Due to loss of the omental fat pad, the SMA compresses the duodenum in this condition, leading to obstruction

Causes

• Any significant weight loss, such as anorexia nervosa, malabsorption
• Hypercatabolic states such as burns, major surgery, severe injuries, or malignancies.
• Respiratory and cardiac achexia
• Spinal lordosis, application of a body cast, short ligament of Treitz, or unusually low origin of SMA

Clinical

• Upper gastrointestinal obstruction. Vomiting.
• Often in a setting of weight loss

Investigations

• Plain radiograph demonstrates a dilated, fluid- and gas-filled stomach.
• Barium radiography shows dilatation of the first and second part of the duodenum, extrinsic compression of the third part, and a collapsed small bowel distal to the crossing of the SMA.
• Contrast-enhanced CT scan or magnetic resonance angiography (MRA) enable visualization of vascular compression of the duodenum and measurement of aortomesenteric distance precisely. Both these procedures are noninvasive and are probably equivalent to angiography
• Endoscopic examination may visualize a pulsatile extrinsic compression suggestive of this condition.

Management

• Traditionally, treatment has consisted of conservative measures such as nasogastric decompression and hyperalimentation followed by oral feeding with frequent small meals.
• Posturing manoeuvres during meals and motility agents may be helpful in some patients. Surgery may be considered if conservative treatment fails. Duodenojejunostomy is effective in the majority of patients
• Laparoscopic duodenojejunostomy offers a new minimally invasive therapeutic approach to SMA syndrome

References