- Superior mesenteric artery syndrome
Name = SMA Syndrome
Caption = Abdominal and pelvic CT scan showing duodenal compression (black arrow) by the
abdominal aortaand the superior mesenteric artery.
Superior mesenteric artery (SMA) syndrome is a rare, life-threatening
gastrointestinaldisorder characterized by a compression of the third portion of the duodenumby the abdominal aorta(AA) and the overlying superior mesenteric artery. The syndrome is typically caused by a decreased 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 fat. In addition, the aortomesenteric distance is decreased to 2-8 milimeters, as opposed to the typical 10-20.
SMA syndrome was first described in 1842 by
Carl Freiherr von Rokitansky. Only 0.013 - 0.3% of upper-gastrointestinal-tract barium studies support a diagnosis of SMA syndrome,cite web
url = http://www.emedicine.com/ped/topic2175.htm
title = Superior Mesenteric Artery Syndrome
accessdate = 2008-04-09
author = Avinash Shetty
WebMD] making it one of the rarest gastrointestinal disorders known to medical science. With only about 400 cases reported in English-language medical literature since the 1800s, recognition of SMA syndrome as a distinct clinical entity is controversial,cite journal
author=Cohen LB, Field SP, Sachar DB
title=The superior mesenteric artery syndrome. The disease that isn't, or is it?
J. Clin. Gastroenterol.
doi=] with some in the medical community doubting its existence entirely. Wilkie published the first comprehensive series of 75 patients in 1927.cite journal
author=Welsch T, Büchler MW, Kienle P
title=Recalling superior mesenteric artery syndrome
SMA syndrome is also known as Wilkie's syndrome, cast syndrome, mesenteric root syndrome, chronic duodenal ileus and intermittent arterio-mesenteric occlusion.cite journal
author=Laffont I, Bensmail D, Rech C, Prigent G, Loubert G, Dizien O
title=Late superior mesenteric artery syndrome in paraplegia: case report and review
doi=10.1038/sj.sc.3101255] It is distinct from
Nutcracker syndrome, which is the entrapment of the left renal veinbetween the AA and the SMA.
Symptoms include early satiety,
nausea, bilious vomitingof large quantities of partially undigested food, extreme postprandial abdominal pain, abdominal distention/distortion, eructation, external hypersensitivity of the abdominal area, and spontaneous weight loss.cite journal
author=Baltazar U, Dunn J, Floresguerra C, Schmidt L, Browder W
title=Superior mesenteric artery syndrome: an uncommon cause of intestinal obstruction
South. Med. J.
doi= [http://www.medscape.com/viewarticle/410569 Free full text with registration] at
Medscape] Weight loss, in turn, increases the duodenal compression, spurring a vicious cycle. [cite web
title=S: Superior mesenteric artery syndrome
date=April 1, 2008
work=GASTROLAB Digestive Dictionary
url=http://www.gastrolab.net/dictes.htm] Symptoms are partially relieved when in the left lateral decubitus or knee-to-chest position. A Hayes maneuver (pressure applied below the umbilicus in cephalad and dorsal direction) elevates the root of the SMA, also easing the constriction. Symptoms are often aggravated when the patient leans to the right or takes a supine (face up) position.
SMA syndrome can be triggered by any condition involving a narrow mesenteric angle. Patients predominantly have a lengthy or even lifelong history of chronic abdominal complaints, with intermittent exacerbations depending on the degree of duodenal compression. Possibilities usually include constitutional genetic factors, such as aesthenic body build, an abnormally high insertion of the duodenum at the
ligament of Treitz, an unusually low origin of the SMA, or intestinal malrotationaround an axis formed by the SMA. [http://www.cma.ca/index.cfm/ci_id/35163/la_id/1.htm] Genetic predisposition is easily aggravated by any of the following: poor motility of the digestive tract, retroperitional tumors, dietary disorders such as anorexia (loss of appetite) or malabsorption, exaggerated lumbar lordosis, visceroptosis, abdominal wall laxity, rapid linear growth without compensatory weight gain (particularly in teenagers), rapid and/or severe weight loss, starvation, catabolicstates (such as cancerand burns), prolonged bed rest, application of body casts, left nephrectomy, spinal cord injury, or scoliosissurgery.
Four of every five patients are thin and sickly. Females are impacted twice as often as males, with 75% of cases occurring between the ages of 10 and 30. Renown American actor, director, producer, and writer
Christopher Reevesuffered from SMA syndrome as a result of spinal cord injury.
Diagnosis of SMA Syndrome is very difficult, and usually one of exclusion. Diagnosis may follow
X-rayexamination revealing duodenal dilation followed by abrupt constriction proximal to the overlying superior mesenteric artery, as well as a delay in transit of four to six hours through the gastroduodenal region. Suggested exams include abdominal and pelvic Computed Tomography(CT) scan and upper gastrointestinal series(UGI). Endoscopyshould be used to rule out other causes of obstruction. Despite the name, SMA syndrome is not a vascularcondition. Vascular imaging studies of the abdomen, including computed tomography and contrast angiography, are often normal. In the case of spinal cord injury, impaired abdominal sensation due to nerve damage makes the clinical picture even more obscure. [cite journal |last=Roth |first=Eliot|coauthors=Fenton LL, Gaebler-Spira DJ, Frost FS, Yarkony GM. |year=1991 |month=May |title=Superior mesenteric artery syndrome in acute traumatic quadriplegia: case reports and literature review. |journal=Arch Phys Med Rehabil. |volume=2 |issue=6 |pages=417–20 |unused_data=|PMID: 2059111 ] Despite multiple case reports, there has been controversy surrounding the diagnosis and even the existence of SMA syndrome since symptoms do not always correlate well with radiologic findings, and may not always improve following surgical correction. [http://www.uptodate.com/patients/content/topic.do?print=true&topicKey=gi_dis/31570&view=print]
In mild or acute cases, conservative treatment should be attempted first, involving the reversal or removal of the precipitating factor with proper
nutritionand replacement of fluid and electrolytes, either by surgically-inserted jejunal feeding tube, nasogastric intubation, or peripherally inserted central catheter(PICC line) administering total parenteral nutrition(TPN). Symptoms typically improve after restoration of weight.cite journal
author=Manu N, Martin L
title=Weight Loss Induced Small Bowel Obstruction
journal=The Internet Journal of Gastroenterology
url=http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijge/vol4n2/weight.xml] 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. This open surgery involves the creation of an alternate route between the
duodenumand the jejunum, [cite web
work=The Free Dictionary
url=http://medical-dictionary.thefreedictionary.com/duodenojejunostomy] bypassing the compression caused by the AA and the SMA. Although highly invasive, duodenojejunostomy has a 90% success rate. Less common surgical treatments for SMA syndrome include gastrojejunostomy,
laparoscopicor Roux-en-Y duodenojejunostomy, anterior transposition of the third portion of the duodenum, intestinal derotation, and division of the ligament of Treitz. Lysis of the duodenal suspensory muscle has the advantage that it does not involve the creation of an intestinal anastomosis. [http://www.cma.ca/index.cfm/ci_id/35163/la_id/1.htm]
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