Superior Mesenteric Artery Syndrome, Pediatric

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Superior Mesenteric Artery Syndrome, Pediatric

Basics

Description

Superior mesenteric artery (SMA) syndrome is extrinsic compression of the third portion of the duodenum between the SMA and aorta.
It is also called Wilkie syndrome, cast syndrome, or aortomesenteric duodenal compression syndrome.
The diagnosis is somewhat controversial because symptoms do not always correlate with radiologic findings and do not always improve following treatment.

Epidemiology

Rare
More common in adolescents
Also seen following corrective scoliosis surgery with a rate of 0.5 " 2.4%

Etiology

The SMA arises from the aorta at the L1 vertebral body level and forms an acute downward aortomesenteric angle that is normally between 35 " 65 degrees, due in part to the mesenteric fat pad.
The third portion of the duodenum lies within the aortomesenteric angle, and narrowing of the angle (<25 degrees) can lead to duodenal compression by the SMA anteriorly and the L3 vertebral body posteriorly.
Any factor that narrows the aortomesenteric angle can cause duodenal compression. Common conditions that predispose to narrowing of this angle are as follows:Illnesses associated with significant weight loss leading to loss of the mesenteric fat pad:Anorexia nervosa, malignancy, spinal cord injury, trauma, or burnsRapid linear growth in childrenIncrease in lordosis of the back such as from immobilization by body cast, scoliosis surgery, or prolonged bed rest in a supine positionWeight percentile for height of <5% is a risk factor for development of SMA syndrome following scoliosis surgery.Variations of the ligament of Treitz: A short ligament lifts the third or fourth part of the duodenum into the narrower segment in the aortomesenteric angle.
If the left renal vein is also compressed, this can lead to microscopic hematuria, also known as nutcracker syndrome.

Illnesses associated with significant weight loss leading to loss of the mesenteric fat pad:Anorexia nervosa, malignancy, spinal cord injury, trauma, or burns
Rapid linear growth in children
Increase in lordosis of the back such as from immobilization by body cast, scoliosis surgery, or prolonged bed rest in a supine positionWeight percentile for height of <5% is a risk factor for development of SMA syndrome following scoliosis surgery.
Variations of the ligament of Treitz: A short ligament lifts the third or fourth part of the duodenum into the narrower segment in the aortomesenteric angle.

Anorexia nervosa, malignancy, spinal cord injury, trauma, or burns

Weight percentile for height of <5% is a risk factor for development of SMA syndrome following scoliosis surgery.

Diagnosis

History

Clinical presentation can be acute or chronic with gradual, progressive symptoms.
Symptoms are generally consistent with proximal small bowel obstruction, including the following:NauseaVomiting (bilious and nonbilious, postprandial)Gastroesophageal refluxEpigastric abdominal painEructationWeight lossEarly satietyDehydrationBloatingFailure to thrive
Symptoms may be relieved when patient is lying prone, in left lateral decubitus, or in knee-chest positions.

Nausea
Vomiting (bilious and nonbilious, postprandial)
Gastroesophageal reflux
Epigastric abdominal pain
Eructation
Weight loss
Early satiety
Dehydration
Bloating
Failure to thrive

Physical Exam

Nonspecific findings of small bowel obstruction include the following:Abdominal distensionSuccussion splashHigh-pitched bowel sounds
No pathognomonic signs or symptoms, but a history of weight loss, immobilization, or back surgery followed by symptoms of early satiety, bloating, and vomiting after meals would suggest the diagnosis.

Abdominal distension
Succussion splash
High-pitched bowel sounds

Diagnostic Tests & Interpretation

Imaging should show duodenal obstruction with dilated stomach and proximal duodenum, active peristalsis, and a narrow angle between the aorta and the SMA.
Abdominal radiograph is usually the initial diagnostic imaging test.Findings can be nonspecific but may also reveal suggestive findings of obstruction, including a distended stomach or a dilated proximal duodenum with a sharp cutoff of the third portion of the duodenum where the SMA crosses the duodenum.
Additional evaluation with upper gastrointestinal (GI) series:Passage of contrast is typically delayed and often stops at the third portion of the duodenum. Contrast passes when the patient is moved to a prone position, where gravity will increase the aortomesenteric angle.Similar findings can be seen with CT.
Additional imaging may be required if the diagnosis remains unclear.Superior mesenteric arteriography with simultaneous barium contrast radiography to show SMA superimposed on duodenumCT and MR angiography have now replaced superior mesenteric arteriography.
An aortomesenteric angle <25 degrees is the most useful diagnostic marker, especially if the aortomesenteric distance is <8 mm.
Determination of the aortomesenteric angle in severe cases may help with decision for surgery.

Findings can be nonspecific but may also reveal suggestive findings of obstruction, including a distended stomach or a dilated proximal duodenum with a sharp cutoff of the third portion of the duodenum where the SMA crosses the duodenum.

Passage of contrast is typically delayed and often stops at the third portion of the duodenum. Contrast passes when the patient is moved to a prone position, where gravity will increase the aortomesenteric angle.
Similar findings can be seen with CT.

Superior mesenteric arteriography with simultaneous barium contrast radiography to show SMA superimposed on duodenum
CT and MR angiography have now replaced superior mesenteric arteriography.

Differential Diagnosis

Causes of small bowel obstruction:Luminal obstruction: foreign bodyIntramural obstruction: duplication cyst, web, tumor, bezoar, strictureExtramural obstruction: tumor, annular pancreas, bands, adhesions, volvulus, intussusception
Duodenal dysmotilityIntrinsic neuronal disorderMuscular weakness (holovisceral myopathy, diabetes)Fibrosis (scleroderma, lupus retroperitoneal fibrosis)Collagen vascular diseasesChronic idiopathic intestinal pseudo-obstruction
Anorexia nervosa/bulimia

Luminal obstruction: foreign body
Intramural obstruction: duplication cyst, web, tumor, bezoar, stricture
Extramural obstruction: tumor, annular pancreas, bands, adhesions, volvulus, intussusception

Intrinsic neuronal disorder
Muscular weakness (holovisceral myopathy, diabetes)
Fibrosis (scleroderma, lupus retroperitoneal fibrosis)
Collagen vascular diseases
Chronic idiopathic intestinal pseudo-obstruction

Treatment

General Measures

Correct fluid and electrolyte imbalances.
Decompress obstruction.Insert nasogastric tube to decompress stomach and proximal duodenum.
Definitive treatment is aimed at correcting the precipitating factor.
Feed to improve nutrition and weight gain.Feeding in a prone or left lateral decubitus position can help relieve pain but may require a jejunal tube to bypass the obstruction.Total parenteral nutrition may be needed if cannot tolerate enteral nutrition.
If a patient had recent spinal surgery:Frequent repositioning of patients in body castsReversal of back surgery may be necessary in some patients.
Surgery is typically unnecessary.Surgery is indicated only if supportive care is ineffective.Usually performed in patients with a prolonged history of weight loss or pronounced duodenal dilationSurgical options include duodenojejunostomy, gastrojejunostomy, or Strong procedure (mobilization of duodenum by dividing the ligament of Treitz).
Consider psychiatric evaluation if eating disorder suspected.

Insert nasogastric tube to decompress stomach and proximal duodenum.

Feeding in a prone or left lateral decubitus position can help relieve pain but may require a jejunal tube to bypass the obstruction.
Total parenteral nutrition may be needed if cannot tolerate enteral nutrition.

Frequent repositioning of patients in body casts
Reversal of back surgery may be necessary in some patients.

Surgery is indicated only if supportive care is ineffective.
Usually performed in patients with a prolonged history of weight loss or pronounced duodenal dilation
Surgical options include duodenojejunostomy, gastrojejunostomy, or Strong procedure (mobilization of duodenum by dividing the ligament of Treitz).

Ongoing Care

Prognosis

Delay in diagnosis of SMA syndrome can result in the following:Electrolyte disturbancesDehydration and malnutritionIn severe cases, possible GI pneumatosis, perforation, formation of a duodenal bezoar, or death
Most patients do not require surgery and improve with supportive care alone.

Electrolyte disturbances
Dehydration and malnutrition
In severe cases, possible GI pneumatosis, perforation, formation of a duodenal bezoar, or death

Additional Reading

Agrawal GA, Johnson PT, Fishman EK. Multidetector row CT of superior mesenteric artery syndrome. J Clin Gastroenterol. 2007;41(1):62 " 65. [View Abstract]
Jain R. Superior mesenteric artery syndrome. Curr Treat Options Gastroenterol. 2007;10(1):24 " 27. [View Abstract]
Kadji M, Naouri A, Bernard P. Superior mesenteric artery syndrome: a case report. Ann Chir. 2006;131(6 " 7):389 " 392. [View Abstract]
Kim IY, Cho NC, Kim DS, et al. Laparoscopic duodenojejunostomy for management of superior mesenteric artery syndrome: two case reports and a review of the literature. Yonsei Med J. 2003;44(3):526 " 529. [View Abstract]
Kurbegov A, Grabb B, Bealer J. Superior mesenteric artery syndrome in a 16-year-old with bilious emesis. Curr Opin Pediatr. 2010;22(5):664 " 667. [View Abstract]
Merrett ND, Wilson RB, Cosman P, et al. Superior mesenteric artery syndrome: diagnosis and treatment strategies. J Gastrointest Surg. 2009;13(2):287 " 292. [View Abstract]
Okugawa Y, Inoue M, Uchida K, et al. Superior mesenteric artery syndrome in an infant: case report and literature review. J Pediatr Surg. 2007;42(10):E5 " E8. [View Abstract]
Schwartz A. Scoliosis, superior mesenteric artery syndrome, and adolescents. Orthop Nurs. 2007;26(1):19 " 24. [View Abstract]
Vulliamy P, Hariharan V, Gutmann J, et al. Superior mesenteric artery syndrome and the "nutcracker phenomenon. " BMJ Case Rep. 2013;21:2013. [View Abstract]
Welsch T, B Όchler MW, Kienle P. Recalling superior mesenteric artery syndrome. Dig Surg. 2007;24(3):149 " 156. [View Abstract]

Codes

ICD09

557.1 Chronic vascular insufficiency of intestine

ICD10

K55.1 Chronic vascular disorders of intestine

SNOMED

197006009 superior mesenteric artery syndrome (disorder)

FAQ

Q: When the diagnosis of SMA syndrome is suspected, what are the next steps in management?
A: The general sequence is to confirm the diagnosis with an imaging study such as an upper GI contrast study and also to initiate supportive care of refeeding and mobilization.
Q: The following treatment modalities are known to be useful in treatment of SMA syndrome: do nothing, or feed with a jejunal tube, a liquid diet, prone feeding, or total parenteral nutrition. Which program works?
A: All of the above have been used in SMA syndrome. Weight gain has also been accomplished with total parenteral nutrition.
Q: Does radiographic testing or a feeding clinical trial help in confirming the diagnosis?
A: Yes. It may be helpful to confirm the diagnosis and look at the aortomesenteric angle with a CT or MR angiography. In addition, a clinical trial of feeding and weight gain often becomes the criterion for confirmation of the diagnosis.