肠系膜上动脉综合征SMA

Superior mesenteric artery syndrome
superior mesenteric artery syndrome is a very rare, life-threatening gastrovascular disorder characterized by a compression of the third portion of the duodenum by the superior mesenteric artery.
Mortality SMA syndrome is estimated to have a mortality rate of 1 in 3. Delay in the diagnosis of SMA syndrome can result in: fatal malnutrition dehydration oliguria electrolyte abnormalities hypokalemia acute gastric rupture intestinal perforation (from prolonged mesenteric ischemia) gastrectasia
causes
The 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. In addition, the aorto-mesenteric distance is 2-8 millimeters, as opposed to the typical 10-20.
SMA syndrome was first described in 1861 by Carl Freiherr von Rokitansky in victims at autopsy, but remained pathologically undefined until 1927 when Wilkie published the first comprehensive series of 75 patients.With only about 500 reported cases in the history of English-language medical literature,SMA syndrome is estimated to have a mortality rate of 1 in 3.
Symptoms
This, in turn, increases the duodenal compression spurring a vicious cycle. Symptoms are partially relieved when in the left lateral ,prone or knee-to-chest position.
Less common surgical treatments for SMA syndrome include Roux-en-Y duodenojejunostomy, gastro-jejunostomy and lysis of the ligs first robotically-assisted intestinal bypass for SMA syndrome was performed on July 30, 2008 at the London Health Sciences Centre in Ontario, Canada.
Treatment
Conservative treatment should be attempted first, involving the reversal or removal of the precipitating factor with proper nutrition and replacement of fluid and electrolytes. Pro-motility agents such as metoclopramide may also be beneficial.
rapid linear adolescent growth spurt, weight loss starvation catabolic states(cancer and burns).
early satiety nausea bilious vomiting extreme"stabbing" postprandial abdominal pain (due to both the duodenal compression and the compensatory reversed peristalsis) severe malnutrition with spontaneous wasting.
Diagnosis postprandial abdominal pain nausea bilious vomiting wasting symptoms relieved via the left lateral ,prone or knee-to-chest position upper gastrointestinal barium abdominal and pelvic CT scan with contrast
SMA syndrome is also known as Wilkie's syndrome, cast syndrome, mesenteric root syndrome, chronic duodenal ileus It is distinct from Nutcracker syndrome,which is the entrapment of the left renal vein between the AA and the SMA.
Symptoms are often aggravated when leaning to the right or taking a supine position.
Demographics
SMA syndrome is extremely rare, evident in only 0.013 - 0.3% of uppergastrointestinal-tract barium studies. As the syndrome involves a lack of essential fat, four of every five afflicted are underweight, often to the point of sickliness and emaciation. Females are impacted twice as often as males, with 75% of cases occurring between the ages of 10 and 30.
Risk anatomic factors such as:
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.
If conservative treatment fails, or if the case is severe or chronic, surgical intervention is required. The most common operation for SMA syndrome, duodenojejunostomy, was first proposed in 1907 by Bloodgood.
Retroperitoneal fat and lymphatic tissue normally serve as a cushion for the duodenum, protecting it from compression by the SMA. SMA syndrome is thus triggered by any condition involving an insubstantial cushion and narrow mesenteric angle.SMA Syndrome can present in two forms: chronic/congenital or acute/induced .
Predisposition easily aggravated such as
poor motility of the digestive tract retroperitional tumors cachexia exaggerated lumbar lordosis visceroptosis abdominal wall laxity peritoneal adhesions abdominal trauma
Upper gastrointestinal series showing extreme duodenal dilation (white arrow) abruptly preceding constriction by the SMA
Abdominal and pelvic CT scan showing duodenal compression (black arrow) by the abdominal aorta and the superior mesenteric artery.