Superior mesenteric artery syndrome
Key points
SMAS (Wilkie syndrome): External compression of the 3rd part of the duodenum between the aorta and SMA, typically when the aortomesenteric angle narrows from normal 38°–56° to <25° and distance decreases to 2–8 mm
Incidence: Rare in children (0.013–0.3%), slight female predominance (F:M ≈3:2)
Pathophysiology
Loss of mesenteric fat pad reduces the aortomesenteric angle → duodenal compression
Congenital causes: High ligament of Treitz, low SMA origin, malrotation
Acquired causes: Rapid weight loss (e.g., eating disorders (Anorexia nervosa), cancer, burns), growth spurts, scoliosis/spine surgery, casts, paraplegia
Clinical Features
Many patients are malnourished or fear eating
Children with SMAS typically present with:
• Chronic Postprandial epigastric pain
• Early satiety and bloating
• Nausea and bilious vomiting
• Weight loss or failure to gain weight
• Relief of symptoms in the knee-chest or left lateral decubitus position
Imaging
CT angiography/contrast CT: Gold standard, measures aortomesenteric angle (<22°) and distance (<8 mm), shows proximal duodenal dilation
UGI series: Shows duodenal obstruction with delayed transit .
Differential Diagnosis
Duodenal atresia or stenosis
Malrotation with midgut volvulus
Associated Conditions
Co-occurrence: Nutcracker syndrome due to similar anatomy, compression of left renal vein while crossing in front of the aorta by the SMA
Post-scoliosis/spine surgery: Mean onset ~9 days; incidence up to 4.7%, especially in underweight adolescents
Others: Hip spica casts, paraplegia, growth spurts, cannabis hyperemesis syndrome
Management
A. Conservative Management (First Line)
Goal: restore weight → widen SMA angle → relieve compression.
NG/decompression, IV fluids/electrolyte correction
Nutritional support (NJ tube, or TPN), prokinetics, posture therapy
B. Surgical Management
Indications: Failure of conservative therapy, persistent vomiting, or complications like gastric perforation.
Duodenojejunostomy (laparoscopic or open): Most performed and successful.
Strong's procedure: Division of the ligament of Treitz to mobilise the duodenum (duodenal de-rotation)
Gastrojejunostomy and SMA transposition: Less commonly used
Outcomes
Many children improve with nutritional rehabilitation alone
Surgical outcomes are excellent, particularly with laparoscopic duodenojejunostomy. Complications are rare but may include leakage or anastomotic stricture.
Page edited by Mr Mahmoud Abdelbary MSc, MRCS August 2025
Page edited by Mrs Charnjit Seehra BSc August 2025
References
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Altiok H, Lubicky JP, DeWald CJ, Herman JE. The superior mesenteric artery syndrome in patients with spinal deformity. Spine (Phila Pa 1976). 2005 Oct 1;30(19):2164-70. doi: 10.1097/01.brs.0000181059.83265.b2. PMID: 16205341.
Pappalardo, G., Pola, E., Bertini, F.A.et al. Superior mesenteric artery syndrome following spine surgery in idiopathic adolescent scoliosis: a systematic review. Eur J Med Res 29, 410 (2024). https://doi.org/10.1186/s40001-024-02002-3