isolated superior mesenteric artery ( sma ) dissection was first reported by bauersfeld   in 1947 and was defined as sma wall dissection not accompanied by aortic dissection .
recently , reports concerning this rare disease have been increasing due to the widespread use of ct for the assessment of abdominal pain .
sma dissection was reported in middle - aged men with hypertension and a smoking habit .
the presence of arteriosclerosis , fibromuscular dysplasia , and elastic tissue degeneration of the arterial wall were described as causes of sma dissection by some investigators .
enhanced ct is useful as initial imaging study for the patients presenting with severe abdominal pain since it can detect various pathological conditions including arterial dissection , although arteriography provides more specific information .
various types of treatments such as conservative , endovascular , and surgical treatments have been reported with some success . however , a widely accepted treatment strategy has not been established because of the rarity of the disease .
sma dissection is an uncommon condition and may cause gut ischemia as well as deteriorate the clinical course of affected patients . therefore ,
it is considered to be one of the most important diseases for a differential diagnosis in the case of acute abdominal pain .
we report a case of sma dissection that was difficult to diagnose , but was later successfully treated by resection of the small intestine .
a 53-year - old man had a sudden onset of abdominal pain and vomiting while playing japanese pinball .
he visited a nearby clinic and received a subcutaneous injection of butylscopolamine 20 mg ; however , the abdominal symptoms did not improve , and he visited our hospital 2 h after the initial onset .
vital signs were stable on arrival ( body temperature 36.0c , blood pressure 125/70 mm hg , and pulse rate 70 beats / min ) , though the patient had a cold sweat and reported nausea .
laboratory studies showed elevated levels of leukocytes ( 14,720/l ) and lactate dehydrogenase ( 306 u / l ) .
aspartate transaminase and alanine aminotransferase values were 32 and 38 u / l , respectively .
his abdomen was flat and soft , and there was tenderness around the navel without peritoneal signs .
he could not lie in a supine position because of his pain and remained in a right lateral position .
ct revealed wall thickness in the upper small intestine , suggesting the possibility of ileitis .
he was admitted to the emergency unit with acute abdominal pain of uncertain cause in order to observe the clinical course .
the patient was subcutaneously administered metoclopramide and pentazocine 15 mg for the abdominal symptoms . despite our recommendation to stay in the hospital ,
he was discharged the next day due to family problems , though the peripheral leukocyte count and c - reactive protein level were elevated to 20,010/l and 4.7 mg / dl , respectively . after returning home , vomiting and abdominal pain continued , and the patient visited the gastroenterology unit of our hospital on the third day after onset .
an examination at that time showed that the abdomen was flat and soft without peritoneal irritation signs , but the patient was admitted again to the gastroenterology ward due to continuous inflammatory response ( leukocyte count 10,780/l , c - reactive protein 10.66 mg / dl ) .
other laboratory findings were within normal ranges ( aspartate transaminase 22 u / l , alanine aminotransferase 29 u / l , and lactate dehydrogenase 172 u / l ) .
following admission , an abdominal ct with contrast enhancement was performed , which revealed wall thickness of the small intestine and a contrast filling defect in the root of the sma ( fig .
1 ) . we made a diagnosis of sma thrombosis and considered emergency treatment , as a portion of the small intestine was not enhanced .
digital subtraction angiography showed a false lumen at the proximal sma and stenosis of the secondary jejunal branch , which was considered to be a feeder to the small intestine with ischemia ( fig .
subsequently , intravascular ultrasonography was performed after selecting the true lumen by use of a microwire catheter .
the flap structure was demonstrated by intravascular ultrasonography and considered to show signs of arterial wall dissection . up to 50% of the true lumen in the proximal sma
neither dilatation nor stent placement was chosen , since blood supply to all branches of the sma was considered to be maintained following the angiography procedure .
abdominal ct with contrast enhancement was performed to detect possible redissection or necrosis of the intestine .
we could not rule out necrosis of the intestine due to ischemia shown on ct findings and decided to perform laparoscopic surgery .
first , the intra - abdominal condition was observed , and no evidence of bloody ascites , inflamed peritoneal membrane , or intestinal adhesion was found . on the other hand ,
a 30-cm region of poor peristalsis was found in the small intestine 40 cm from the anal side of the ligament of treitz ( fig .
no arterial beating was observed in the region of the small intestine , and the color of the serosa was whitish .
based on these findings , resection of part of the small intestine was considered necessary .
the mucosal side of the resected specimen was black and had a blistered appearance , with fibrin spread through part the specimen .
microscopic histopathological imaging of the region showed hemorrhage and congestion extending to all layers , as well as necrotic changes with inflammatory cell infiltration in the submucosal layer , which was compatible with hemorrhagic necrotic jejunitis .
the patient demonstrated a good clinical course after surgery , and antihypertensive drugs were started .
a follow - up enhanced ct examination showed narrowing of the false lumen of the sma and no new dissection .
partial ischemia of the small intestine caused by sma dissection must be considered for patients with undifferentiated severe abdominal pain , and enhanced ct should be performed in the early stage .
stenosis of the true lumen due to compression from a false lumen can lead to progression of ischemia in cases of arterial dissection . in our patient ,
ct findings showed partial ischemia of the small intestine due to severe stenosis of the secondary ileal branch .
such dissections have been reported to be as long as 38.0  15.1 mm at onset .
therefore , if the dissection extends to the branch with a narrow lumen , the area of the small intestine supplied by the feeder can easily become ischemic . on the other hand ,
if an embolism caused by thrombus occurs in the sma , the long segment of the small intestine will become ischemic .
therefore , the length of the involved small intestine is considered to be important to differentiate sma dissection from sma thrombosis .
it is necessary take into account the possibility of sma dissection when partial ischemia is found in patients with undifferentiated abdominal pain .
enhanced ct should be performed in the early stage for a patient with unexplained severe abdominal pain .
contrast - enhanced ct findings are reported to be more useful than those obtained with plain ct to evaluate an existing lesion , intestinal wall thickness , and ascites , as plain ct results can mislead to a diagnosis of sma dissection .
reported characteristic ct findings of sma dissection include thrombosis of a false lumen , an intimal flap , an enlarged sma diameter , increased attenuation of fat around the sma , and hematoma in the mesentery with hemorrhagic ascites .
however , it should be noted that not all cases necessarily have an intimal flap , and some show only an enlarged sma diameter and increased attenuation of the fat around the sma .
morris et al .   reported that angiography following a ct examination clearly showed sma dissection . in the present case , we were not able to make a definitive diagnosis based on the first enhanced ct examination and only reached our final decision based on subsequent sma angiography . thus , enhanced ct followed by abdominal angiography should be done for patients with unexplained severe abdominal pain , as appropriate .
others recently reported that ct angiography is useful for the diagnosis of sma dissection , because dissection can be more readily diagnosed compared with conventional angiography .
we recommend that conventional angiography be performed only for patients who may require endovascular treatment in the future . in conclusion ,
partial ischemia of the small intestine in cases with explained abdominal pain indicates the possibility of sma dissection .
contrast - enhanced ct should be considered in the early stage for an accurate diagnosis .
although sma dissection is relatively rare in cases with acute abdominal symptoms , awareness of the condition is important for differential diagnosis .
 superior mesenteric artery ( sma ) dissection without aortic dissection is a rare condition , and its diagnosis is considered to be difficult . 
 intestinal infarction is a severe complication of the disease , which may require resection of the intestine . 
 we present a case of isolated sma dissection . 
 a 53-year - old man experienced sudden pain in the abdomen while playing japanese pinball and was admitted to our hospital due to acute abdominal symptoms of uncertain cause . 
 enhanced ct revealed a defect of the root of the sma , while angiography and intravascular ultrasound findings showed dissection of the sma wall . 
 conservative treatment was chosen at the time , while a part of the small intestine was eventually resected because of progressive ischemia . 
 although sma dissection is a rare occurrence in cases with acute abdominal symptoms , awareness of the condition is important for differential diagnosis . 
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