Superior mesenteric artery syndrome (SMAS), also known as Wilkie’s syndrome or cast syndrome, is a rare but serious disorder that causes compression of the duodenum between the abdominal aorta and the superior mesenteric artery. This narrowing disrupts the normal passage of food and fluid through the digestive tract, often leading to pain, nausea, and significant weight loss. Because the symptoms can mimic more common gastrointestinal issues, diagnosis is often delayed until malnutrition has already developed. With timely recognition and appropriate treatment, outcomes are generally favorable. 

Superior mesenteric artery syndrome is fundamentally a mechanical problem involving narrowing of the angle between the superior mesenteric artery and the aorta. In healthy individuals, this angle ranges from 38 to 65 degrees, with a protective fat cushion preventing compression of the duodenum. In SMAS, rapid or severe weight loss depletes this cushion, reducing the angle to less than 25 degrees and the space between vessels to as little as 2 to 8 millimeters. The duodenum becomes compressed, blocking food and fluid flow and causing discomfort and nutritional challenges. 

Without intervention, SMAS can create a self-perpetuating cycle: eating causes pain, which leads to reduced intake, further weight loss, and worsening compression. 

SMAS typically develops when anatomical changes reduce the space between the aorta and superior mesenteric artery. The most common scenarios include: 

• Significant weight loss: From eating disorders, cancer, chronic infection, or trauma 

• Prolonged immobility: Muscle and fat wasting during extended bed rest 

• Spinal surgery: Especially scoliosis correction, which alters vessel alignment 

• Congenital anatomical factors: Rare cases of naturally narrow angles or high duodenum position 

• Chronic malnutrition: From conditions such as celiac disease, tuberculosis, or HIV 

Once the duodenum is compressed, eating becomes painful, which reinforces the cycle of weight loss and worsening compression. 

Symptoms of superior mesenteric artery syndrome vary in severity but generally reflect obstruction of the duodenum. Patients may first notice vague digestive discomfort that becomes more defined after meals. The pain and fullness often mimic more common conditions, which can delay recognition. When symptoms progress, patients often report: 

• Upper abdominal pain after eating, often crampy or pressure-like 

• Nausea and vomiting, sometimes bile-stained 

• Early satiety and bloating after small meals 

• Progressive weight loss 

• Symptom relief in positions such as prone, knees-to-chest, or left lateral side-lying 

If untreated, SMAS can cause severe malnutrition, dehydration, and electrolyte imbalances. 

Diagnosis is challenging because symptoms overlap with other gastrointestinal conditions. A combination of history, clinical findings, and imaging is typically required. Clinicians must also consider differential diagnoses, as SMAS can mimic peptic ulcer disease, chronic pancreatitis, functional dyspepsia, irritable bowel syndrome, or even eating disorders. Ruling out these conditions is essential before confirming SMAS. 

Diagnosis is challenging because symptoms overlap with other gastrointestinal conditions. A combination of history, clinical findings, and imaging is typically required. 

Diagnostic tools include: 

• Barium upper gastrointestinal series: Shows dilated stomach and duodenum with abrupt cutoff 

• CT angiography or MR angiography: Measures aortomesenteric angle and distance 

• Doppler ultrasound: May demonstrate narrowing but depends on operator skill 

• Upper endoscopy: Rules out alternative causes such as ulcers or tumors 

Confirmation comes from correlating imaging findings with the clinical presentation. 

Treatment focuses on relieving duodenal compression and restoring nutritional balance. Conservative measures are the first step, with surgery reserved for persistent or severe cases. 

Conservative management: 

• Nutritional rehabilitation with frequent, high-calorie meals 

• Enteral feeding via nasojejunal tube if oral intake is insufficient 

• Hydration and electrolyte correction 

• Postural strategies such as lying prone or with knees-to-chest after meals 

• Regular monitoring of weight and symptom improvement 

Surgical management: 

• Duodenojejunostomy: Bypasses the compressed segment with high success rates 

• Strong’s procedure: Divides the ligament of Treitz to reposition the duodenum 

• Gastrojejunostomy: Rarely used today as it bypasses but does not relieve compression 

• Minimally invasive laparoscopic techniques are preferred for reduced recovery time 

The outlook is excellent with timely treatment. Many patients improve with nutritional rehabilitation alone. Those who require surgery generally experience long-term symptom resolution. Delayed diagnosis, however, can lead to prolonged malnutrition and complications. 

Superior mesenteric artery syndrome is an uncommon but important cause of gastrointestinal obstruction. Clinicians should consider it in patients with unexplained abdominal pain, early satiety, vomiting, and weight loss, particularly following rapid weight reduction. With early recognition and either conservative or surgical treatment, patients can achieve full recovery. 

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