Superior Mesenteric Artery (SMA) syndrome is a rare condition where the third part of the duodenum is compressed between the abdominal aorta and SMA, causing gastric outlet obstruction. It occurs when the angle between the vessels decreases below normal, usually due to weight loss or other factors. Symptoms include early satiety, nausea, vomiting and abdominal pain. Diagnosis involves imaging tests to measure the aortomesenteric angle and distance. Treatment ranges from nutritional support and positioning changes to surgery like duodenojejunostomy to bypass the obstruction. SMA syndrome is difficult to diagnose and treat, but awareness of risk factors and appropriate management can help resolve symptoms.

1. Superior Mesenteric
Artery syndrome
Supervision by : Pro. Dr. Mohammed Noman Albadani
and
Dr. Sonia Alabsi
Done by :Dr. Hussam A. Aldomini

2. Definition :
• is a gastro-vascular disorder in which the third
and final portion of the duodenum is compressed
between the abdominal aorta (AA) and the
overlying superior mesenteric artery.
• This rare, potentially life-threatening syndrome is
typically caused by an angle of 6°–25° between
the AA and the SMA, in comparison to the normal
range of 38°–56°, due to a lack of retroperitoneal
and visceral fat (mesenteric fat). In addition, the
aortomesenteric distance is 2–8 millimeters, as
opposed to the typical 10–20.

3. Other names to the syndrome :
1. Wilkie's syndrome
2. Cast syndrome
3. Mesenteric root syndrome
4. Chronic duodenal ileus
5. Intermittent arterio-mesenteric occlusion
• It is distinct from nutcracker syndrome, which
is the entrapment of the left renal
vein between the AA and the SMA, although it
is possible to be diagnosed with both

5. Etiology
• SMA syndrome is thus triggered by any condition involving an
insubstantial cushion and narrow mesenteric angle. It can
present in two forms: chronic/congenital or acute/induced.
1. Chronic/congenital form of SMA syndrome predominantly
have a lengthy or even lifelong history of abdominal
complaints with intermittent exacerbations depending on the
degree of duodenal compression.
• Risk factors include anatomic characteristics such as: aesthenic (very
thin or "lanky") body build, an unusually high insertion of the
duodenum at the ligament of Treitz, a particularly low origin of the SMA,
or intestinal malrotation around an axis formed by the SMA.
• Predisposition is easily aggravated by any of the following: poor
motility of the digestive tract, retroperitoneal tumors, loss of
appetite, malabsorption, cachexia, exaggerated

6. continue
2. Acute form of SMA syndrome develops rapidly after
traumatic incidents that forcibly hyper-extend the SMA
across the duodenum, inducing the obstruction, or
sudden weight loss for any reason.
Causes include prolonged supine bed rest, scoliosis
surgery, left nephrectomy, ileo-anal pouch surgery.
• It is important to note, however, that while SMA syndrome
can mimic an eating disorder, distinguishing the two
conditions is extremely important, as misdiagnosis in this
situation can be dangerous.

7. Clinical presentation
• Early satiety, nausea, bilious and semidigested vomiting,
extreme "stabbing" postprandial abdominal pain (due to both
the duodenal compression and the compensatory
reversed peristalsis), abdominal distention/distortion, burping,
external hypersensitivity or tenderness of the abdominal
area, reflux, and heartburn.
• In infants, feeding difficulties and poor weight gain are also
frequent symptoms.
• In some cases of SMA syndrome,
severe malnutrition accompanying spontaneous wasting may
occur. This, in turn, increases the duodenal compression, which
worsens the underlying cause, creating a cycle of worsening
symptoms.
• Fear of eating is a commonly seen among those with the
chronic form of SMA syndrome. For many, symptoms are

8. Epidemiology
In US, the precise incidence of this entity is unknown.
• It is estimated to be 0.1% to 0.3% of case refer to Upper GI
series.
• Females to males ratio is 3:2.
Sequels of delay in the diagnosis of SMAS can result in:
• Malnutrition, dehydration, electrolyte abnormalities.
• Gastric pneumatosis and portal venous gas, formation of an
obstructing duodenal bezoar.
• Hypovolemia secondary to massive GI hemorrhage, and
even death secondary to gastric perforation.

9. Diagnosis
• Is very difficult, and usually one of exclusion.
• Diagnosis may follow X-ray examination revealing duodenal
dilation followed by abrupt constriction proximal to the
overlying SMA.
• Standard diagnostic exams include abdominal and
pelvic computed tomography (CT) scan with oral and IV
contrast, upper gastrointestinal series (UGI), and, for equivocal
cases, hypotonic duodenography.
• Criteria in CT scan : is aortomesenteric angle of less than 22
degree and distance of less 10-8 mm. In children, an angle of
less 20 degree.
• The reason for the persistence of gastrointestinal symptoms

12. Differential diagnosis
1. Post-operative paralytic ileus
2. Causes of upper GI obstruction
3. Duodenal dysmotility syndrome
• Diabetes mellitus
• Collagen vascular disease
• Scleroderma
• Chronic idiopathic intestinal pseudo-obstruction

13. Treatment
• According to a number of recent sources, at least 70% of cases
can typically be treated with medical treatment, while the rest
require surgical treatment.
• In some cases, emergency surgery is necessary upon
presentation.
• A six-week trial of medical treatment is recommended in
pediatric cases.
• The goal of medical treatment for SMA syndrome is resolution
of underlying conditions and weight gain.
• Medical treatment may involve nasogastric tube placement for
duodenal and gastric decompression, mobilization into the
prone or left lateral decubitus position, the reversal or removal
of the precipitating factor with proper nutrition and replacement
of fluid and electrolytes, either by surgically inserted

14. Surgical management
• The most common operation for SMA syndrome,
duodenojejunostomy.
• Less common surgical treatments for SMA syndrome
include Roux-en-Y duodenojejunostomy,
gastrojejunostomy, anterior transposition of the third
portion of the duodenum, intestinal derotation, division of
the ligament of Treitz (Strong's operation), and
transposition of the SMA.
• Both transposition of the SMA and lysis of the duodenal
suspensory muscle have the advantage that they do not
involve the creation of an intestinal anastomosis, also can

16. References
1. Medscape
2. Wikipedia
3. Internet lectures
4. www.smasyndrome.org