superior mesenteric artery ( sma ) syndrome , also known as wilkie syndrome or cast syndrome , is an uncommon disease that results from sma compression of the third portion of the duodenum.1 the diagnosis of sma syndrome should be considered in a young underweight patient ( i.e. , low body mass index [ bmi ] ) presenting with abdominal pain , nausea , anorexia , weight loss , and vomiting.2 conventionally , the diagnosis is made using upper barium study or computed tomography ( ct ) . to our knowledge , eus has been used to diagnose sma syndrome in a single case reported in the korean literature,3 using a mini probe .
no case studies of sma syndrome have reported the development of this disorder in a patient with normal bmi .
therefore , we report a case of sma syndrome diagnosed with the aid of linear endoscopic ultrasound ( eus ) in a patient with normal bmi .
a 61-year - old female visited the emergency room complaining of sudden abdominal pain and nausea after overeating .
she visited a local clinic where she underwent abdominal ct and was prescribed an analgesic , but the pain did not subside , so she visited our hospital .
her blood pressure was 120/80 mm hg , pulse rate 68 per minute , respiratory rate 18 per minute , body temperature 36.9 , height 157 cm , weight 50 kg , and bmi 20.3 .
the complete blood count showed leukocytes 10,600/l , hemoglobin 13.3 g / dl , and platelet count 208,000/l .
the blood chemistry showed total bilirubin 0.5 mg / dl , aspartate aminotransferase 18 u / l , alanine aminotransferase 13 u / l , amylase 106 u / l , blood urea nitrogen 23 mg / dl , creatinine 0.67 mg / dl , and c - reactive protein 0.26 mg / dl .  
the initial abdominal x - ray revealed a large amount of food distending the stomach and mild gas accumulation in the small and large bowel ( fig .
1a ) . an abdominal ct taken at the local clinic showed a hugely distended stomach and duodenum ( fig .
the aortomesenteric distance on ct was 7.4 mm which was decreased than normal mean aortomesenteric distance of 10 to 28 mm in healthy people.4 conventional barium studies , which still play an important role for diagnosis of sma syndrome , could not be performed because of severe gastroptosis and distended stomach .
then we performed esophagogastroduodenoscopy ( egd ) and eus to rule out intestinal intraluminal obstruction and gastric or duodenal ulcer disease that might be secondary to reflux or that might constitute a primary pathology mimicking sma syndrome.5 egd revealed a huge amount of food in the stomach ( fig .
that eus could give us more information about surrounding organs which can directly compress the duodenum , we performed linear eus ( eg3870-utk ; pentax , tokyo , japan ) .
this did not show any abnormality of the gallbladder , common bile duct or pancreas .
however , it showed the sma running almost parallel to the abdominal aorta , with an aortomesenteric angle of 10 ( normal range , 38 to 65 ) , confirming the diagnosis of sma syndrome ( fig .
the abdominal pain and nausea were relieved and the patient started a soft diet on day 5 of admission and was discharged on day 7 of admission without any symptoms .
sma syndrome is uncommon and characterized by postprandial epigastric pain , nausea , vomiting , anorexia , and weight loss.5 the symptoms of sma syndrome are similar to those of small bowel obstruction , and include vomiting , nausea , early satiety , anorexia , and abdominal pain.6,7 the symptoms occur after or are aggravated by eating.4 sma syndrome is favored by particular anatomic conditions , such as a short or hypertrophic ligament of treitz , a low origin of the sma , intestinal malrotation , and lumbar hyperlordosis.8 undernutrition or rapid weight loss leads to reduced thickness of the adipose tissue in the aortomesenteric space.8 the following fluoroscopy - based radiological criteria are indicative of sma syndrome : dilatation of the first and second parts of the duodenum with or without gastric dilatation , abrupt vertical or oblique compression of the third part of the duodenum , antiperistaltic waves of barium proximal to the obstruction , significant delay in gastroduodenal transit , and relief of the obstruction after postural changes.9 however , an upper barium study is of limited use for evaluation of sma syndrome due to severe gastroptosis .
the vascular abnormalities are well - delineated on fine - slice ct imaging with vascular reconstruction10 and measurement of the aorta - sma angle.2 however , an upper barium study and ct involve considerable radiation exposure , especially in children or adolescents .
the endoscopic approach minimizes the exposure to radiation , which might be of substantial benefit for young patients.4 the upper endoscopic findings of duodenal dilatation , stasis , and antiperistaltic waves suggest the presence of sma syndrome .
however , one must rule out other causes , especially duodenal obstruction . the diagnosis of sma syndrome using upper endoscopy
, endoscopy is of minor diagnostic value.11 however , upper gastrointestinal endoscopy should be performed to rule out intestinal intraluminal obstruction and gastric or duodenal ulcer disease that might be secondary to reflux or that might constitute a primary pathology , mimicking sma syndrome.5 although the endoscopic features of duodenal dilatation and stenosis are suggestive of sma syndrome , other pathologies that present with features resembling those of sma syndrome must be excluded .
the main anatomical feature of this syndrome is the narrowing of the angle between the sma and the aorta , which is normally 38 to 65.2 in sma syndrome , this angle is typically decreased to 6 to 25.12 the angle measured by linear eus in our patient was 10. the measurement of the aortomesenteric angle may be different according to the positional change .
however , we believe that measurements have acceptable aortomesenteric angle differences among each position . the cause of this narrowing , other than congenital abnormality , is postulated to be related to the loss of intra - abdominal adipose tissue,2 which narrows the aorto - sma angle , resulting in functional obstruction.2 kim et al.3 reported the diagnosis of sma syndrome using mini probe eus . in the study ,
mini probe eus was performed to evaluate the maximal aortomesenteric distance . in this study ,
upper gastrointestinal barium series to assess the diagnosis was limited by the presence of severe gastroptosis .
linear eus can provide simultaneous endoscopic and ultrasonographic images of the stomach , duodenum , and surrounding structures .
recently , linear eus was reported to be a useful diagnostic modality for evaluation of the aortomesenteric angle.13 in this context , linear eus can confirm sma syndrome without exposure to radiation or contrast medium .
in addition , our patient showed x - ray findings of a ptotic , dilated stomach , which can prevent barium passage into the duodenum . in other words ,
linear eus imaging of the aortomesenteric angle can be obtained by scanning the abdominal aorta and sma at the stomach position . after identifying the liver ,
the celiac artery and sma are imaged when the scope is advanced caudally from this position along the abdominal aorta .
however , the sma is often difficult to image , particularly in sma syndrome patients , due to artifacts related to retained food or air in the stomach . because the scanning position of the mini probe is where the descending duodenal segment narrows,3,14 linear eus from that position would assist imaging of the aortomesenteric angle .
the assessment of aortomesenteric angle during deflation of the balloon appears to be reflective of accurate angle because the balloon inflation may cause narrowing of the angle by compression .
individuals who are underweight or have lost weight are at increased risk of sma syndrome.5 interestingly , our patient had a normal bmi with no history of weight loss .
there is a report of patients with a normal bmi and sma syndrome , suggesting that low bmi is not necessary for its development.15 weight loss does not appear to be responsible for all cases .
for example , sma syndrome is common following corrective spinal surgery for scoliosis.5 this procedure lengthens the spine cranially , displacing the sma origin , decreasing the lateral mobility of the mesenteric artery , and reducing the acuteness of the aortomesenteric angle .
the development of sma syndrome may also be related to variation or distortion of the normal anatomy , such as short ligament of treitz,5 low origin of the sma,4 or esophagectomy.16 a case report of identical twins17 with sma syndrome and another case in utero18 suggest a genetic predisposition in some patients .
therefore , anatomical variation or genetic susceptibility might have contributed to the sma syndrome in our case .
sma syndrome is a rare disease that presents with nonspecific symptoms that could delay diagnosis and treatment .
this suggests that egd with linear eus could play an important role in the early diagnosis and treatment of sma syndrome .
our case illustrates that sma syndrome can occur in patients with normal bmi , although being underweight appears to predispose to its development .
although sma syndrome is not typically within the scope of practice of endosonographers , it is useful to get familiar with the findings .
 superior mesenteric artery ( sma ) syndrome is an uncommon disease that results from sma compression of the third portion of the duodenum . 
 patients with sma syndrome present with upper gastrointestinal symptoms , such as nausea , vomiting , and abdominal pain . 
 the diagnosis is usually made from an upper barium study or computed tomography . 
 typically , sma syndrome is caused by a decreased aortomesenteric angle of 6 to 25. an underweight body mass index ( bmi ) is a risk factor for development of sma syndrome . 
 there are few reports of the role of linear endoscopic ultrasound ( eus ) in the diagnosis of sma syndrome . 
 we report a case of sma syndrome , with normal bmi , that was diagnosed with the aid of linear eus . 
 although sma syndrome is not typically within the scope of practice of endosonographers , it is useful to get familiar with the findings . 
INTRODUCTION
CASE REPORT
DISCUSSION