|
Superior mesenteric artery (SMA) syndrome is a rare, potentially life-threatening gastro-vascular disorder characterized by a compression of the third and final portion of the duodenum by the abdominal aorta (AA) and the overlying superior mesenteric artery. 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 (mesenteric fat). In addition, the aortomesenteric distance is 2-8 millimeters, as opposed to the typical 10-20.〔 However, a narrow SMA angle alone is not enough to make a diagnosis, because patients with a low BMI, most notably children, have been known to have a narrow SMA angle with no symptoms of SMA syndrome. 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. According to a 1956 study, only .3% of patients referred for an upper-gastrointestinal-tract barium studies fit this diagnosis, making it one of the rarest gastrointestinal disorders known to medical science. Recognition of SMA syndrome as a distinct clinical entity is controversial, due in part to its possible confusion with a number of other conditions, though it is now widely acknowledged. SMA syndrome is also known as Wilkie's syndrome, cast syndrome, mesenteric root syndrome, chronic duodenal ileus and intermittent arterio-mesenteric occlusion. It is distinct from Nutcracker syndrome, which is the entrapment of the left renal vein between the AA and the SMA, although it is possible to be diagnosed with both conditions. == Signs and symptoms == Signs and symptoms include early satiety, nausea, vomiting, extreme "stabbing" postprandial abdominal pain (due to both the duodenal compression and the compensatory reversed peristalsis), abdominal distention/distortion, eructation, external hypersensitivity or tenderness of the abdominal area, diarrhea, reflux, and heartburn. In infants, feeding difficulties and poor weight gain are also frequent symptoms. In some cases of SMA Syndrome, severe malnutrition accompanying spontaneous wasting may occur.〔(Free full text with registration ) at Medscape〕 This, in turn, increases the duodenal compression, spurring a vicious cycle. "Food fear" is a common development among patients with the chronic form of SMA syndrome. For many, symptoms are partially relieved when in the left lateral decubitus or knee-to-chest position, or in the prone (face down) position. A Hayes maneuver (pressure applied below the umbilicus in cephalad and dorsal direction) elevates the root of the SMA, also slightly easing the constriction. Symptoms can be aggravated when leaning to the right or taking a supine (face up) position.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「superior mesenteric artery syndrome」の詳細全文を読む スポンサード リンク
|