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Superior mesenteric artery syndrome (SMAS), also known as Wilkie
syndrome, arteriomesenteric duodenal compression, chronic duodenal
ileus, or cast syndrome, was first described by von Rokitansky in
1842, and is an unusual form of gastrointestinal obstruction resulting
from compression of the duodenum between the abdominal aorta posteriorly and
the superior mesenteric artery anteriorly (Fig.
406-1).1 In 1878, Willet documented the development
of SMAS in association with orthopedic casting; however, it was
not until 1927 that Wilkie formally characterized SMAS in a series
of 75 patients.2,3 To date, the diagnosis, and to some
extent the existence, of SMAS remains controversial as symptoms
do not always correlate with radiologic findings and may not improve
with surgical correction)
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SMAS is a rare form of intestinal obstruction
with a reported incidence ranging from 0.01% to 0.3%.4,5,6 SMAS
is found more commonly in females than males and typically affects
individuals of slender build after acute weight loss, such as from
hyperthyroidism, anorexia nervosa, or even gastroenteritis. SMAS
also affects individuals following orthopedic casting, especially
following scoliosis surgery or following the application of a hip-spica
cast.7 Acute or chronic neurologic injury is associated
with superior mesenteric artery syndrome.8 Other associated
disorders include fungal abscess, gastric bezoar, pregnancy, and
aneurysms of the superior mesenteric artery.
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The superior mesenteric artery (SMA) usually arises from the
anterior aspect of the aorta at the level of the first lumbar vertebral body
and is surrounded by fat and lymphatic tissue. The artery then extends
caudally at an acute angle into the mesentery. The duodenum passes
between the aorta and the proximal SMA commonly at the level of
the third lumbar vertebral body. The duodenum is suspended within
the angle created by the aorta and SMA by the ligament of Treitz
(Fig. 406-1). In the majority of the population, the
angle between the superior mesenteric artery and the aorta is between
45 and 60 degrees. This angle is in part due to the presence of
an anterior mesenteric fat pad, the size of which correlates with body
mass index.9 In SMAS, the angle between the aorta and the
SMA is reduced to as little as 6 degrees, allowing the SMA to compress
the duodenum against the aorta, resulting in mechanical obstruction.
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Although, to date, no genetic mutations have been associated
with SMAS, Iwaoka documents the development of SMAS in identical twin
males without any previous risk factors or surgeries.5 In
addition, Ortiz reported a case of familial SMAS with 5 out of 8 family
members developing SMAS, including a father and his 4 ...