Signs and symptomsEdit
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, [8] reflux, and heartburn. [9] In infants, feeding difficulties and poor weight gain are also frequent symptoms. [10] In some cases of SMA Syndrome, severe malnutrition accompanying spontaneous wasting may occur. [11]
This, in turn, increases the duodenal compression, spurring a vicious cycle. [12] "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. [11]
CausesEdit
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.
Patients with the chronic, congenital form of SMA syndrome predominantly have a lengthy or even lifelong history of abdominal complaints with intermittent exacerbations depending on the degree of duodenal compression. Risk factors include anatomic characteristics such as: aesthenic (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, or intestinal malrotation around an axis formed by the SMA. [13] Predisposition is easily aggravated by any of the following: poor motility of the digestive tract, [6]
retroperitional tumors, loss of appetite, malabsorption, cachexia, exaggerated lumbar lordosis, visceroptosis, abdominal wall laxity, peritoneal adhesions, abdominal trauma, [14] rapid linear adolescent growth spurt, weight loss, starvation, catabolic states (as with cancer and burns), and history of neurological injury. [15]
The acute form of SMA syndrome develops rapidly after traumatic incidents that forcibly hyper-extend the SMA across the duodenum, inducing the obstruction, or severe, rapid weight loss for any reason. Causes include prolonged supine bed rest (as with the application of body casts), spinal cord injury, scoliosis, scoliosis surgery, left nephrectomy, [1] ileo-anal pouch surgery, [16] or eating disorder. [17]
However, while SMA Syndrome can be caused by, or mimic, an eating disorder, distinguishing the two conditions is extremely important, as misdiagnosis in this situation can be dangerous. [18]
DiagnosisEdit
Abdominal and pelvic computed tomography scan showing duodenal compression (black arrow) by the superior mesenteric artery (red arrow) and the abdominal aorta (blue arrow).
Upper gastrointestinal series showing extreme duodenal dilation (white arrow) abruptly preceding constriction by the SMA.
A diagram of a healthy mesenteric angle.
A diagram of a compressed duodenum due to a reduced mesenteric angle.
Diagnosis is very difficult, and usually one of exclusion. SMA syndrome is thus considered only after patients have undergone an extensive evaluation of their gastrointestinal tract including upper endoscopy, colonoscopy, and evaluation for various malabsorptive, ulcerative and inflammatory instestinal conditions with a higher diagnostic frequency. Diagnosis may follow x-ray examination revealing duodenal dilation followed by abrupt constriction proximal to the overlying SMA, as well as a delay in transit of four to six hours through the gastroduodenal region. Standard diagnostic exams include abdominal and pelvic computed tomography (CT) scan with oral and IV contrast, upper gastrointestinal series (UGI), and, for equivocal cases, hypotonic duodenography. In addition, vascular imaging studies such as ultrasound and contrast angiography may be used to indicate increased bloodflow velocity through the SMA or a narrowed SMA angle. [19][20]
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. [21]
However, the reason for the persistence of gastrointestinal symptoms even after surgical correction in some cases has been traced to the remaining prominence of reversed peristalsis in contrast to direct peristalsis. [22]
Since females between the ages of 10 and 30 are most frequently afflicted, it is not uncommon for physicians to initially and incorrectly assume that emaciation is a choice of the patient instead of a consequence of SMA syndrome. Patients in the earlier stages of SMA syndrome often remain unaware that they are ill until substantial damage to their health is done, since they may attempt to adapt to the condition by gradually decreasing their food intake or naturally gravitating toward a lighter and more digestible diet. Eating disorder treatment protocols involving forced refeeding and behavioral therapy are noted to have poor outcomes with individuals suffering from SMA syndrome, contributing to the high mortality rate of the condition. [23]
TreatmentEdit
Upper gastrointestinal series showing duodenojejuonostomy (white arrow).
SMA syndrome can present in acute, acquired form (e.g. abruptly emerging within an inpatient stay following scoliosis surgery) as well as chronic form (i.e. developing throughout the course of a lifetime and advancing due to environmental triggers, life changes, or other illnesses). At least 70% of cases can typically be treated with medical treatment, while the rest require surgical treatment. [9][15][24]
Medical treatment should be attempted first in all cases, except for cases where emergency surgery is necessary upon presentation. [15] A six-week trial of medical treatment is recommended in pediatric cases. [9] The goal of medical treatment for SMA Syndrome is resolution of underlying conditions and weight gain. Medical treatment may involve nasogastric tube placement for duodenal and gastric decompression, mobilization into the prone or left lateral decubitus position, [25] the reversal or removal of the precipitating factor with proper nutrition and 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). Pro-motility agents such as metoclopramide may also be beneficial. [26] Symptoms typically improve after restoration of weight, [27]
except when reversed peristalsis persists, or if regained fat refuses to accumulate within the mesenteric angle. [22] Most patients seem to benefit from nutritional support with hyperalimentation irrespective of disease history. [28]
If medical treatment fails, or is not feasible due to severe illness, surgical intervention is required. The most common operation for SMA syndrome, duodenojejunostomy, was first proposed in 1907 by Bloodgood. [11]
Performed as either an open surgery or laparoscopically, duodenojejunostomy involves the creation of an anastomosis between the duodenum and the jejunum, [29] bypassing the compression caused by the AA and the SMA. [1] Less common surgical treatments for SMA syndrome include Roux-en-Y duodenojejunostomy, gastrojejunostomy, anterior transposition of the third portion of the duodenum, intestinal derotation, division of the ligament of Treitz (Strong's operation), and transposition of the SMA. [30] Both transposition of the SMA and lysis of the duodenal suspensory muscle have the advantage that they do not involve the creation of an intestinal anastomosis. [13]
The possible persistence of symptoms after surgical bypass can be traced to the remaining prominence of reversed peristalsis in contrast to direct peristalsis, although the precipitating factor (the duodenal compression) has been bypassed or relieved. Reversed peristalsis has been shown to respond to duodenal circular drainage—a complex and invasive open surgical procedure originally implemented and performed in China. [22]
In some cases, SMA Syndrome may occur alongside a serious, life-threatening condition such as cancer or AIDS. Even in these cases, though, treatment of the SMA Syndrome can lead to a reduction in symptoms and an increased quality of life. [31][32]
PrognosisEdit
Delay in the diagnosis of SMA syndrome can result in fatal catabolysis (advanced malnutrition), dehydration, electrolyte abnormalities, hypokalemia, acute gastric rupture or intestinal perforation (from prolonged mesenteric ischemia), gastric distention, spontaneous upper gastrointestinal bleeding, hypovolemic shock, aspiration pneumonia, or sudden cardiovascular collapse. [1][19][33]
A 1-in-3 mortality rate for Superior Mesenteric Artery syndrome has been reported by a small number of sources. [34][35] However, after extensive research, original data establishing this mortality rate has not been found, indicating that the number is likely to be unreliable. While research establishing an official mortality rate may not exist, two recent studies of SMA syndrome patients, one published in 2006 looking at 22 cases [15] and one in 2012 looking at 80 cases, [24] show mortality rates of 0% [15] and 6.3%, [24] respectively. The expected outcome for SMA syndrome treatment is generally considered to be excellent. [15]
EpidemiologyEdit
SMA syndrome is extremely rare, evident in only 0.3% of upper-gastrointestinal-tract barium studies. [4]
However, unfamiliarity with this c
สัญญาณและ symptomsEditอาการรวมสามารถช่วง คลื่นไส้ อาเจียน มาก "แทง" postprandial ปวดท้อง (เพราะบีบ duodenal ทั้ง peristalsis กลับชดเชย), distention ท้องเพี้ยน eructation ไวต่อยาภายนอก หรือกดเจ็บบริเวณท้อง ท้องเสีย กรดไหลย้อน [8] และจุกเสียด ทารกใน [9] ให้อาหารความยากลำบากและน้ำหนักดียังมีอาการบ่อย [10] ในบางกรณีอาการ SMA ขาดสารอาหารรุนแรงพร้อมอยู่เสียอาจเกิดขึ้น [11]นี้ กลับ เพิ่มรวม duodenal หนุนรอบทายา [12] "กลัวอาหาร" เป็นการพัฒนาร่วมกันระหว่างผู้ป่วยกับ SMA อาการแบบเรื้อรัง สำหรับหลาย ๆ คน อาการบางส่วนเบาใจเมื่ออย่างไร decubitus ด้านข้างซ้ายหรือเข่าหน้าอกตำแหน่ง หรือการเสี่ยงตำแหน่ง (หน้าลง) วิธีเฮยส์ (กดดันด้านล่าง umbilicus ใน cephalad และทิศทาง dorsal) ยกระดับรากของ SMA เล็กน้อยผ่อนคลายการเชื่อม สามารถ aggravated อาการเมื่อเอียงขวาหรือตำแหน่ง supine (หน้าค่าตาได้ [11]CausesEditRetroperitoneal เนื้อเยื่อไขมัน และต่อมน้ำเหลืองทำหน้าที่เป็นเบาะสำหรับ duodenum ปกป้องจากการบีบอัดโดยการหมุนปกติ กลุ่มอาการ SMA จะถูกทริกเกอร์ โดยเงื่อนไขใด ๆ มีเบาะ insubstantial และมุมแคบ mesenteric จึง กลุ่มอาการ SMA สามารถนำเสนอในรูปแบบที่สอง: / เกิดเฉียบพลัน หรือเรื้อรัง/ประจำตัวได้ผู้ป่วยที่ มีแบบฟอร์มแต่กำเนิด โรคของกลุ่มอาการ SMA ส่วนใหญ่มีประวัติยาวนาน หรือแม้แต่รองท้องร้องเรียนกับ exacerbations ไม่ต่อเนื่องขึ้นอยู่กับระดับของการบีบอัด duodenal ปัจจัยเสี่ยงได้แก่ anatomic ลักษณะเช่น: aesthenic (มากบาง หรือ "lanky") ร่างกายสร้าง แทรกสูงผิดปกติของ duodenum ที่เอ็นของ Treitz กำเนิดต่ำโดยเฉพาะอย่างยิ่งของ SMA หรือลำไส้ malrotation รอบแกน โดยการหมุนที่เกิดขึ้น [13] predisposition คือง่าย ๆ aggravated โดยต่อไปนี้: ดี motility ของทางเดินอาหาร, [6]retroperitional เนื้องอก สูญเสียความอยากอาหาร malabsorption, cachexia, lordosis exaggerated ช่องไข visceroptosis, laxity ผนังท้อง peritoneal adhesions บาดเจ็บที่ช่องท้อง spurt เติบโตวัยรุ่นเส้นอย่างรวดเร็ว [14] น้ำหนักสูญหาย ความอดอยาก อเมริกา catabolic (เช่นเดียวกับโรคมะเร็งและไหม้), และประวัติของการบาดเจ็บระบบประสาท [15]แบบเฉียบพลันของกลุ่มอาการ SMA พัฒนาอย่างรวดเร็วหลังจากเหตุการณ์ที่เจ็บปวดที่บังคับให้ไฮเปอร์ขยายหมุนข้าม duodenum, inducing อุดตัน หรือการสูญเสียน้ำหนักอย่างรวดเร็ว อย่างรุนแรงด้วยเหตุผลใด ๆ สาเหตุรวมเตียงนาน supine เหลือ (ตาม ด้วยร่างกาย casts), สันหลังบาดเจ็บ ปกครอง ผ่าตัดปกครอง nephrectomy ซ้าย ผ่า ตัดกระเป๋า ileo ทางทวารหนัก [1], [16] หรือโรค eating [17]อย่างไรก็ตาม ในขณะที่สามารถเกิดจากกลุ่มอาการ SMA หรือเลียนแบบ ผิดปกติ eating แยกสองเงื่อนไขเป็นสิ่งสำคัญมาก เป็น misdiagnosis ในสถานการณ์นี้ได้อันตราย [18]DiagnosisEditเครื่องเอ็กซเรย์คอมพิวเตอร์ของคำนวณช่องท้อง และอุ้งเชิงกรานสแกนแสดงอัด duodenal (ลูกศรสีดำ) โดยหลอดเลือด mesenteric ซู (ลูกศรสีแดง) และ aorta ในช่องท้อง (ลูกศรสีน้ำเงิน)บนระบบชุดแสดงมาก duodenal dilation (ลูกศรสีขาว) ก่อนเชื่อม โดยหมุนกะทันหันไดอะแกรมของเป็นมุม mesenteric สุขภาพไดอะแกรมของ duodenum ยิ่งเนื่องจากเป็นมุม mesenteric ลดลงวินิจฉัยได้ยาก และโดยปกติหนึ่งแยกออก จึงถือว่ากลุ่มอาการ SMA หลังจากผู้ป่วยที่มีระดับการประเมินของระบบทางเดินบนส่องกล้อง colonoscopy และประเมินเงื่อนไข instestinal malabsorptive, ulcerative และอักเสบต่าง ๆ ด้วยความถี่สูงวินิจฉัยอย่างละเอียด การวินิจฉัยอาจติดตามตรวจเอ็กซ์เรย์ที่เปิดเผยตามอย่างทันทีทันใดที่เชื่อม proximal จะหมุนเหล่านั้น ตลอดจนความล่าช้าในการขนส่งสี่ถึงหกชั่วโมงผ่านภูมิภาค gastroduodenal dilation duodenal สอบมาตรฐานการวินิจฉัยได้แก่การสแกนช่องท้อง และอุ้งเชิงกรานจากการคำนวณเครื่องเอ็กซเรย์คอมพิวเตอร์ (CT) มีปากและ IV ความคมชัด ชุดระบบบน (UGI), และ กรณี equivocal, hypotonic duodenography นอกจากนี้ การศึกษาเกี่ยวกับภาพของหลอดเลือดเช่นการฉีดสีหลอดอัลตร้าซาวด์และความคมชัดอาจใช้เพื่อบ่งชี้ bloodflow เพิ่มความเร็ว โดยการหมุนหรือเป็นมุม SMA narrowed [19] [20]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. [21]However, the reason for the persistence of gastrointestinal symptoms even after surgical correction in some cases has been traced to the remaining prominence of reversed peristalsis in contrast to direct peristalsis. [22]Since females between the ages of 10 and 30 are most frequently afflicted, it is not uncommon for physicians to initially and incorrectly assume that emaciation is a choice of the patient instead of a consequence of SMA syndrome. Patients in the earlier stages of SMA syndrome often remain unaware that they are ill until substantial damage to their health is done, since they may attempt to adapt to the condition by gradually decreasing their food intake or naturally gravitating toward a lighter and more digestible diet. Eating disorder treatment protocols involving forced refeeding and behavioral therapy are noted to have poor outcomes with individuals suffering from SMA syndrome, contributing to the high mortality rate of the condition. [23]TreatmentEditUpper gastrointestinal series showing duodenojejuonostomy (white arrow).SMA syndrome can present in acute, acquired form (e.g. abruptly emerging within an inpatient stay following scoliosis surgery) as well as chronic form (i.e. developing throughout the course of a lifetime and advancing due to environmental triggers, life changes, or other illnesses). At least 70% of cases can typically be treated with medical treatment, while the rest require surgical treatment. [9][15][24]Medical treatment should be attempted first in all cases, except for cases where emergency surgery is necessary upon presentation. [15] A six-week trial of medical treatment is recommended in pediatric cases. [9] The goal of medical treatment for SMA Syndrome is resolution of underlying conditions and weight gain. Medical treatment may involve nasogastric tube placement for duodenal and gastric decompression, mobilization into the prone or left lateral decubitus position, [25] the reversal or removal of the precipitating factor with proper nutrition and 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). Pro-motility agents such as metoclopramide may also be beneficial. [26] Symptoms typically improve after restoration of weight, [27]except when reversed peristalsis persists, or if regained fat refuses to accumulate within the mesenteric angle. [22] Most patients seem to benefit from nutritional support with hyperalimentation irrespective of disease history. [28]If medical treatment fails, or is not feasible due to severe illness, surgical intervention is required. The most common operation for SMA syndrome, duodenojejunostomy, was first proposed in 1907 by Bloodgood. [11]Performed as either an open surgery or laparoscopically, duodenojejunostomy involves the creation of an anastomosis between the duodenum and the jejunum, [29] bypassing the compression caused by the AA and the SMA. [1] Less common surgical treatments for SMA syndrome include Roux-en-Y duodenojejunostomy, gastrojejunostomy, anterior transposition of the third portion of the duodenum, intestinal derotation, division of the ligament of Treitz (Strong's operation), and transposition of the SMA. [30] Both transposition of the SMA and lysis of the duodenal suspensory muscle have the advantage that they do not involve the creation of an intestinal anastomosis. [13]The possible persistence of symptoms after surgical bypass can be traced to the remaining prominence of reversed peristalsis in contrast to direct peristalsis, although the precipitating factor (the duodenal compression) has been bypassed or relieved. Reversed peristalsis has been shown to respond to duodenal circular drainage—a complex and invasive open surgical procedure originally implemented and performed in China. [22]In some cases, SMA Syndrome may occur alongside a serious, life-threatening condition such as cancer or AIDS. Even in these cases, though, treatment of the SMA Syndrome can lead to a reduction in symptoms and an increased quality of life. [31][32]
PrognosisEdit
Delay in the diagnosis of SMA syndrome can result in fatal catabolysis (advanced malnutrition), dehydration, electrolyte abnormalities, hypokalemia, acute gastric rupture or intestinal perforation (from prolonged mesenteric ischemia), gastric distention, spontaneous upper gastrointestinal bleeding, hypovolemic shock, aspiration pneumonia, or sudden cardiovascular collapse. [1][19][33]
A 1-in-3 mortality rate for Superior Mesenteric Artery syndrome has been reported by a small number of sources. [34][35] However, after extensive research, original data establishing this mortality rate has not been found, indicating that the number is likely to be unreliable. While research establishing an official mortality rate may not exist, two recent studies of SMA syndrome patients, one published in 2006 looking at 22 cases [15] and one in 2012 looking at 80 cases, [24] show mortality rates of 0% [15] and 6.3%, [24] respectively. The expected outcome for SMA syndrome treatment is generally considered to be excellent. [15]
EpidemiologyEdit
SMA syndrome is extremely rare, evident in only 0.3% of upper-gastrointestinal-tract barium studies. [4]
However, unfamiliarity with this c
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