GASTROINTESTINAL MOTILITY AND FUNCTIONAL BOWEL DISORDERS, SERIES #3 GASTROINTESTINAL MOTILITY AND FUNCTIONAL BOWEL DISORDERS, SERIES #3

Richard W. McCallum, MD, FACP, FRACP (Aust), FACG Superior Mesenteric Artery Syndrome

Yi Jia Omar Sosa Richard W. McCallum

INTRODUCTION uperior mesenteric artery (SMA) syndrome was 33%.12-15 In the usual clinical setting its nonspecific first described in 1842 by Rotikansky during an presentations can result in under-diagnosis and severe Sautopsy for compression.1 Wilkie outcomes.16,17 in 1921 defined the patho-physiological changes of The recognition of SMA syndrome as a distinct the third (transverse) portion of the duodenum when clinical entity remains controversial because it can be obstructed by arteriomesenteric compression and used confused with other anatomic or motility-related causes the term “chronic duodenal ileus”.2 He published the of duodenal obstruction.4,5,18 The left renal vein may also first comprehensive SMA syndrome case series of 75 be entrapped and compressed between the aorta and patients in 1927.3 Since then, approximately 500 cases the SMA, a clinical setting referred to as “nutcracker of SMA syndrome have been reported.4,5 syndrome”.5 The symptoms of SMA syndrome do not SMA syndrome, also known as Wilkie disease, always correlate well with abnormal anatomic findings duodenal arterial mesenteric compression, duodenal on radiologic studies, and may not resolve completely ileus, aortomesenteric artery compression, and after treatment.4,18,19 It was often regarded as a diagnostic cast syndrome, is an uncommon and sometime life dilemma and a diagnosis of exclusion. In this article we threatening gastrointestinal-vascular disorder.6-8 Some will review the pathophysiology, symptoms, diagnosis studies report the incidence of SMA syndrome to be and treatment of SMA syndrome. 0.013-0.3% of the general population.9,10 Approximately 0.013-0.78% of routine upper GI barium studies identify Pathophysiology SMA compression suggesting this diagnosis.11 75% of Anatomically, the third portion of the duodenum the patients reported with SMA syndrome are aged 10- typically crosses caudal to the origin of SMA, passing 30 years and predominantly females.4,9,10 A delay in the between the aorta and the superior mesenteric artery diagnosis of SMA syndrome can result in malnutrition, at the level of 3rd lumbar vertebral body, and being electrolyte inbalance, gastric perforation, pneumatosis suspended by its attachment to the ligament of Treitz and hypovolemia, with a reported mortality rate up to (Figure 1). SMA normally arises from the anterior aspect of the aorta at the level of the L1 vertebral body, Yi Jia, M.D., Ph.D. Omar Sosa, M.D. Richard W. and is enveloped in fatty and lymphatic tissue. It forms McCallum, M.D. Texas Tech University Health a takeoff angle of approximately 45° (normal range 38- Sciences Center, Paul L. Foster School of Medicine, 65°) from the abdominal aorta with the normal mean Department of Internal Medicine, El Paso, TX aorto-mesenteric distance of 10-28 mm.17,20,21

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Figure 1. Anatomy of Superior Mesenteric Artery, Duodenum, and Figure 2. Small bowel series with oral contrast could Aorta. The third part of the duodenum crosses caudal to the origin show significant prolonged retention of barium proximal of SMA, passing between the aorta and the superior mesenteric to the third portion of duodenum with distal narrowing at artery and suspended by its attachment to the ligament of Treitz. the 4th part, while the jejunum looks normal in caliber.

Any factor that decreases this takeoff angle and instrumentation or body casting resulting in prolonged narrows the aorto-mesenteric distance can compress the post operation recovery. This procedure can displace third part of the duodenum as it passes between the SMA the origin of the superior mesenteric artery by anteriorly and the spine posteriorly, resulting in SMA relative lengthening of the spine, reducing the aorto- syndrome. In the case of SMA syndrome, this takeoff mesenteric takeoff angle and decreasing the mesenteric angle can be sharply narrowed to approximately 6-25° artery’s lateral mobility, which is also termed as “cast and the aorto-mesenteric distance can be decreased to syndrome”.14,31-33 It has been demonstrated that the 2-8 mm, causing entrapment of the third part of the incidence of SMA syndrome after surgical procedures duodenum and mechanical obstruction at the level of the for correction of spinal deformities varies between 0.5 third and fourth parts of the duodenum (Figure 2).6,18,20,22 and 4.7%.14,34-36 Predisposing conditions for SMA syndrome that Group C is a function of intraabdominal anatomy, can change the aorto-mesenteric angle have been either congenital or acquired, such as compression or categorized into three groups. Group A is a function mesenteric tension (e.g. aortic ), low origin of of weight loss. Significant weight loss leading to loss the superior mesenteric artery, following esophagectomy of the mesenteric fat pad and accompanying decreased where gastric pull up into the chest changes the upper body mass index is the most common cause of SMA GI anatomy and peritoneal adhesions.37-39 A congenital syndrome. Reduction of the retro-peritoneal fat, which short ligament of Treitz may pull the duodenum up lies between the duodenum and the spine allows the towards the insertion of the aorto-mesenteric angle SMA to compress the duodenum against the vertebrae. predisposing to SMA and malrotation of the small In the absence of an appropriate fatty support, the angle bowel is another predisposing factor.40 at which the SMA leaves the aorta promotes more compression of the third portion of the duodenum.23,24 Symptoms This weight loss can be a consequence of medical, SMA syndrome patients may present acutely or more psychological or surgery disorders, malignancy, insidiously with progressive nonspecific symptoms, malabsorption syndromes, human immunodeficiency the severity depending on the degree of duodenal viral infection, trauma, anorexia, burns, bariatric obstruction.19 Acute presentations can be related to post- surgery, diabetes mellitus and eating disorders.7,25-30 traumatic surgery and often develop from 6-12 days Group B is attributed to external causes, such after surgery, and are explained by hyperextension of the as the corrective spinal surgery for scoliosis with SMA compressing the duodenum, sometimes combined

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33,34 with prolonged periods in surgical casts. Another Table 1. Differential Diagnosis of Clinical Entities pattern of presentation is in the setting of substantial “Mimicking” SMA Syndrome weight loss that could be related to an eating disorder, limited oral intake or disorders or cachexia Functional bowel disorders and duodenal, of malignancy or serious depression. A more insidious small bowel dysmotility presentation that may be seen by gastroenterologists Diabetic gastroparesis involves a long history of abdominal symptoms, where the link to compression of the duodenum is Chronic pancreatitis overlooked.41 Patients with mild obstruction may have only postprandial epigastric pain and early Systematic autoimmune disease satiety, while those with more advanced obstruction may have severe , postprandial , Chronic mesenteric ischemia bilious emesis and weight loss.6,41 These symptoms are associated with reduced food intake related to delayed Idiopathic intestinal pseudo-obstruction gastric emptying from the retropulsion of food from the duodenal compression with the accompanying Megaduodenum compensatory reversed peristalsis. A key aspect of the history that needs to be elicited is that the symptoms are Connective tissue diseases (scleroderma) definitely exacerbated by a meal and are better when fasting or overnight. Other aspects of the history include Post prandial pain of unknown origin worsening if lying on the right side or supine, and relief by the Hayes maneuver (pressure applied below the Irritable bowel syndrome umbilicus in cephalad and dorsal direction), lying prone, knee-chest, or left lateral decubitus positioning.4,10,42 Dyspepsia These positions of alleviation remove tension from the mesentery and SMA, elevating the root of the SMA Peptic ulcer and increasing the aorto-mesenteric angle and distance. Findings on physical examination are nonspecific but H. pylori gastritis can include , a succussion splash, and high-pitched bowel sounds. Because of the nonspecific nature of the symptoms, bezoar, gastric dilation with a risk of perforation and clinicians need a high degree of suspicion in order pneumatosis, which could portend a fatal outcome.12,15,44 to diagnose SMA syndrome. The diagnosis is often Some patients may be receiving chronic narcotics for delayed and arrived at through the process of excluding pain relief, which will further inhibit duodenal and other etiologies of intestinal lumen obstruction.41 The gastric motility promoting postprandial vomiting.42 differential diagnosis of SMA syndrome includes other causes of bowel obstruction, duodenal dysmotility Diagnosis and gastroparesis such as diabetic gastroparesis, The diagnosis of SMA syndrome is usually established chronic pancreatitis, systematic autoimmune disease, by combinations of abdominal radiographs with barium chronic mesenteric ischemia, idiopathic intestinal study, ultrasonography, Computed tomographic (CT) pseudo-obstruction, megaduodenum, often caused by angiography, and magnetic resonance imaging (MRI).45-47 connective tissue diseases, especially scleroderma.10,43 Although less high technology and more “old school”, Post prandial pain of unknown origin, irritable bowel we still recommend an upper GI barium study with syndrome, dyspepsia, including peptic ulcer and H. a small bowel follow through and Doppler blood pylori gastritis may also be the working diagnosis in flow assessment as the initial diagnostic evaluations patients with nonspecific symptoms (Table 1). of SMA syndrome. Another advantage of abdominal Delay in recognition of SMA syndrome can often radiographs and ultrasound is the low cost. Their result in complications, such as severe electrolyte findings may demonstrate a dilated proximal duodenum abnormalities, malnutrition, obstructing duodenal (continued on page 16)

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(continued from page 14) with an abrupt termination of the barium column in the third and fourth part of the duodenum proximal to the ligament of Treitz with a normal jejunal caliber beyond the ligament of Treitz.10 In addition, this oral contrast study could show significantly prolonged retention of barium proximal to the third portion of duodenum and hold up before entering the jejunum as well as dilation of the proximal duodenum and stomach associated with retrograde flow of contrast from reverse peristalsis (Figure 3).19 It is key to have an informed radiologist performing the small bowel series and the clinician needs to be involved and interacting to help interpret the findings with the radiologist. Follow up EGD to investigate these radiographic findings can reveal old Figure 3. CT and MRI angiography with three-dimen- food in the stomach, duodenal dilation with or without sional reconstruction can calculate the aorto-mesenteric bezoar formation, and obstruction at the end of the third angle and also the distance of the aorto-mesenteric part of duodenum. take off as well as the amount of intra-abdominal and Conventional arteriography was traditionally retroperitoneal fat tissue to diagnose SMA syndrome. performed simultaneously with the barium study to demonstrate the superior mesenteric artery superimposed define if the aorto-mesenteric angle is ≤25° and the upon the barium-filled duodenum with the decreased aorto-mesenteric distance is ≤8 mm. Other features aorto-mesenteric angle.4 Ultrasound is a noninvasive to note are high fixation of the duodenum by the method to evaluate the mesenteric artery anatomy and ligament of Treitz, or abnormally low origin of the measure the aorto-mesenteric angle.45,48 Positional superior mesenteric artery or anomalies of the superior maneuvers, such as having patients in the lateral mesenteric artery. decubitus or even standing, may identify alterations Patients with SMA syndrome usually have in the aorto-mesenteric angle. undergone extensive gastrointestinal evaluation and has recently been effective in demonstrating in more procedures over a period of time, including upper detail and better definition the anatomic abnormalities gastrointestinal endoscopy and , to associated with SMA syndrome.49 exclude malabsorptive, ulcerative and inflammatory More advanced imaging studies, such as CT and intestinal conditions. These procedures are expensive, MRI angiography, are often ordered in the setting of have potential risk for patients, and add to the overall patients with variable abdominal pain with nausea and economic burden associated with diagnosing this vomiting and unclear diagnosis.47 These noninvasive elusive entity.5,40 When faced with a diagnostic dilemma images can provide additional anatomic details such of unknown etiology of abdominal pain or nausea and as the compressed bowel in relation to vessels, and vomiting, the gastroenterologist should take or re-take a calculate the aorto-mesenteric angle and the amount thorough history and review the imaging studies keeping of intra-abdominal and retroperitoneal fat tissue.10,46 in mind some less common entities in the differential Recently three-dimensional reconstruction has revealed diagnosis, such as the possibility of undiagnosed SMA. increased blood flow velocity through the SMA and may unexpectedly reveal other possible causes of Treatment the abdominal pain, such as abdominal aneurysm Initial conservative treatment with reversal of any (Figure 4).47 precipitating factor is recommended in all patients The diagnosis of SMA syndrome should come to with superior mesenteric artery syndrome.5,10 Initial mind in patients with clinical features of duodenal gastric decompression by nasogastric tube aspiration obstruction and imaging results revealing duodenal can reduce the dilated stomach and proximal duodenum obstruction in the third portion with active retrograde and help to monitor fluid balance.5 Patients with acute peristalsis. More studies should then be pursued to SMA syndrome usually have electrolyte imbalances,

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Figure 4. The symptoms of SMA Syndrome, are due to narrowed Figure 5. Surgical operations for SMA syndrome. A. Strong’s aorto-mesenteric angle variably defined as less than 25 degrees, procedure. B. Gastrojejunostomy. C. Duodenojejunostomy is and reduced aorto-mesenteric distance which is less than 8-10 accomplished without division. This is the preferred surgery; mm. This is best appreciated on a CT scan with contrast. or with D. Not recommended as the best option since there is division of the 4th portion of the duodenum. Reproduced with permission from: Scovell S, Hamdan A. Superior which should be monitored and corrected aggressively. mesenteric artery syndrome. In: UpToDate, Post TW (Ed), Nutritional support and attempts to increase weight are UpToDate, Waltham, MA. (Accessed on [DATE].) Copyright © 2014 important initial considerations. These approaches may UpToDate, Inc. For more information visit: www.uptodate.com include an enteral nasojejunal feeding tube if it can be successfully passed through the narrowed duodenum, concerns for adequacy of wound healing after surgery. or a laparoscopic placement of a jejunal feeding tube The most common surgical operation for SMA beyond the ligament of Treitz may be necessary for a syndrome is duodenojejunostomy, in which the short period of 3 to 6 months. Total parenteral nutrition compressed portion of the duodenum is actually is not recommended because of complications. All these bypassed by constructing an anastomosis between the 2nd measures are aimed at increasing the fat pad between portion of the duodenum and proximal jejunum anterior the spine and duodenum.49,50 to the superior mesenteric artery. Duodenojejunostomy Patients with suspected eating disorders need can reestablish the bowel continuity with a success rate professional nutritional and psychiatric evaluation > 90%.16 (Figure 5C, the preferred surgery) Another to help achieve optimal calorie replacement.5 Pro- version of this duodenojejunostomy is division of motility medications, such as metoclopramide, are not the 4th part of the duodenum. (Figure 5D) This is not appropriate since increasing upper GI motility when the recommended best option but rather the approach duodenal obstruction is present increases the pain of leaving the duodenum-jejunal continuity intact is component. Antiemetics can be supportive. Younger the preferred surgery. Surgical complications include patients in particular with acute SMA syndrome would bleeding, leakage or stricture at the anatomies site.51 benefit from conservative treatment, which should be Long term concerns include small bowel bacterial instituted for at least 3 to 6 months.5,8 overgrowth in the “blind loop” created in the bypassed Specific indications for surgery in patients with 3rd and 4th parts of duodenum. chronic SMA syndrome include failed conservative Another surgical option is gastrojejunostomy treatment, long-standing symptoms, continuing weight (bypass the obstruction by bringing up loop of jejunum loss due to abdominal pain, nausea and vomiting and to the stomach and anastomosis) (Figure 5B). This reduced food intake, and marked duodenal dilatation may be a potential consideration when adhesions from with stasis.5,40 (Figure 5) Co-management with previous surgeries prevent adequate access to create dieticians and psychiatry consultation when appropriate the Duodeno-jejunal anastomosis. Another surgical are recommended to ensure the best outcomes including approach is the Strong’s procedure (duodenal derotation

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GASTROINTESTINAL MOTILITY AND FUNCTIONAL BOWEL DISORDERS, SERIES #3 with lysis of the ligament of Treitz).8,22,52 However, with these clues, the possibility of SMA syndrome has this procedure is now largely of historic interest to come to mind, so the next logical step is to get a “road and has a higher failure rate to relieve the duodenal map” and obtain an upper GI and small bowel series. obstruction.5 Successful laparoscopic techniques for the If the clinical suspicion is borne out by a suggestive duodenojejunostomy and Strong procedures have been contrast study then more sophisticated noninvasive described.53,54 Although current literature is limited to imaging can be pursued to demonstrate the specific case reports and small studies, laparoscopic approaches features we have summarized in this review. SMA offer a less invasive surgical option. An important point syndrome patients need initial conservative treatment to address is that all of these surgeries have one thing in where reversible aspects, particularly nutrition, are common; the SMA itself is never displaced, re-routed the focus. Surgical options are effective for non- or surgically altered. This is a key anatomic feature of responding patients, although complete resolution of the surgeries. all symptoms may not always be achieved. The role Long term outcomes in SMA syndrome patients of explanation, education and practicing the “art of after surgery are limited in the literature. One series medicine” are all important features in the total care of 16 patients found significant weight gain, but most and outcome of these patients. Making a diagnosis in symptoms remained unchanged except for decreased a patient who has been told there is no explanation vomiting.4 The need to address eating disorders, for the abdominal pain, nausea and vomiting is very bulimia, and underlying psychiatric issues is a key satisfying, particularly when there is a treatable and aspect of post-surgery management. A recent series of reversible entity involved. Such is the world of SMA 8 patients described improved symptoms but no weight syndrome, an often overlooked entity. n gain.5 Surgical morbidity and mortality can be affected by other comorbidities, e.g. diabetes, and end-stage References renal disease.55 1. Rokitansky C. Handbuch der pathologischen Anatomie. 1st ed. Wien: Braunmuller and Seidel. 1842;3:181. CONCLUSION 2. Wilkie DPD. Chronic duodenal ileus. Br J Surg. 1921;9(34):204- Superior mesenteric artery (SMA) syndrome is 214. 3. Wilkie DPD. Chronic duodenal ileus. Am J Med Sci. an uncommon but well recognized clinical entity 1927;173:643–649. characterized by compression of the third portion of the 4. Ylinen P, Kinnunen J, Hockerstedt K. Superior mesenteric artery syndrome. A follow-up study of 16 operated patients. J Clin duodenum between the aorta and the superior mesenteric Gastroenterol. Aug 1989;11(4):386-391. artery. This can result in an acute presentation or more 5. Merrett ND, Wilson RB, Cosman P, Biankin AV. Superior mes- enteric artery syndrome: diagnosis and treatment strategies. J commonly chronic nonspecific symptoms explained by Gastrointest Surg. Feb 2009;13(2):287-292. duodenal obstruction with decreased aorto-mesenteric 6. Baltazar U, Dunn J, Floresguerra C, Schmidt L, Browder W. angle and distance. The SMA syndrome has a spectrum Superior mesenteric artery syndrome: an uncommon cause of intestinal obstruction. South Med J. Jun 2000;93(6):606-608. of symptoms, which can be referred to as “great 7. Adson DE, Mitchell JE, Trenkner SW. The superior mesenteric mimickers” of a GI motility disturbance. The main GI artery syndrome and acute gastric dilatation in eating disorders: a report of two cases and a review of the literature. Int J Eat motility conditions that would be encompassed are: Disord. Mar 1997;21(2):103-114. delayed gastric empting; dilated duodenum suggesting 8. Biank V, Werlin S. Superior mesenteric artery syndrome in chil- dren: a 20-year experience. J Pediatr Gastroenterol Nutr. May intestinal pseudo-obstruction; unexplained nausea and 2006;42(5):522-525. vomiting and abdominal pain, suggesting the spectrum 9. Jain R. Superior mesenteric artery syndrome. Curr Treat Options Gastroenterol. Feb 2007;10(1):24-27. of cycle vomiting syndrome on one hand, and irritable 10. Welsch T, Buchler MW, Kienle P. Recalling superior mesenteric bowel syndrome on the other hand. This is a great artery syndrome. Chin Med Assoc. 2007;24(3):149-156. challenge to the physician in practice. 11. Anderson JR, Earnshaw PM, Fraser GM. Extrinsic compres- sion of the third part of the duodenum. Clin Radiol. Jan We recommend that clinicians focus on the 1982;33(1):75-81. following “clinical pearls”: 1) unexplained abdominal 12. Lim JE, Duke GL, Eachempati SR. Superior mesenteric artery syndrome presenting with acute massive gastric dilatation, pain provoked by eating and accompanied by nausea gastric wall pneumatosis, and portal venous gas. Surgery. Nov and vomiting; 2) endoscopic evidence of retained food 2003;134(5):840-843. 13. Ko KH, Tsai SH, Yu CY, Huang GS, Liu CH, Chang WC. in the stomach and a dilated proximal duodenum; 3) a Unusual complication of superior mesenteric artery syndrome: slow scintigraphic gastric emptying result (Retention spontaneous upper gastrointestinal bleeding with hypovolemic of >60% of isotope at 2hrs and >10% at 4hrs). Armed shock. J Chin Med Assoc. Jan 2009;72(1):45-47.

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14. Crowther MA, Webb PJ, Eyre-Brook IA. Superior mesenteric Surg Am. Oct 2006;88(10):2252-2257. artery syndrome following surgery for scoliosis. Spine (Phila Pa 37. Iwaoka Y, Yamada M, Takehira Y, et al. Superior mesenteric 1976). Dec 15 2002;27(24):E528-533. artery syndrome in identical twin brothers. Intern Med. Aug 15. Kensinger CD, Mukherjee K, Nealon WH, Solorzano CC. 2001;40(8):713-715. Superior mesenteric artery syndrome presenting with pneu- 38. Tseng CK, Su WB, Lai HC, et al. Superior mesenteric artery moperitoneum and pneumomediastinum. Am Surg. Jun syndrome caused by celiac axis compression syndrome: a case 2013;79(6):E240-242. report and review of the literature. Eur J Gastroenterol Hepatol. 16. Fromm S, Cash JM. Superior mesenteric artery syndrome: Jun 2008;20(6):578-582. an approach to the diagnosis and management of upper gas- 39. Cho KR, Jo WM. Superior mesenteric artery syndrome after trointestinal obstruction of unclear etiology. S D J Med. Nov esophagectomy with cervical esophagogastrostomy. Ann Thorac 1990;43(11):5-10. Surg. Nov 2006;82(5):e37-38. 17. Lunca S, Rikkers A, Stanescu A. Acute massive gastric dilata- 40. Bandres D, Ortiz A, Dib J, Jr. Superior mesenteric artery syn- tion: severe ischemia and gastric necrosis without perforation. drome. Gastrointest Endosc. Jul 2008;68(1):152-153. Rom J Gastroenterol. Sep 2005;14(3):279-283. 41. Payawal JH, Cohen AJ, Stamos MJ. Superior mesenteric artery 18. Hines JR, Gore RM, Ballantyne GH. Superior mesenteric artery syndrome involving the duodenum and jejunum. Emerg Radiol. syndrome. Diagnostic criteria and therapeutic approaches. Am J Apr 2004;10(5):273-275. Surg. Nov 1984;148(5):630-632. 42. Kwan E, Lau H, Lee F. Wilkie’s syndrome. Surgery. Feb 19. Cohen LB, Field SP, Sachar DB. The superior mesenteric artery 2004;135(2):225-227. syndrome. The disease that isn’t, or is it? J Clin Gastroenterol. 43. Anderson FH. Megaduodenum. A case report and literature Apr 1985;7(2):113-116. review. Am J Gastroenterol. Dec 1974;62(6):509-515. 20. Wayne ER, Burrington JD. Duodenal obstruction by the superior 44. Fuhrman MA, Felig DM, Tanchel ME. Superior mesenteric mesenteric artery in children. Surg. Nov 1972;72(5):762-768. artery syndrome with obstructing duodenal bezoar. Gastrointest 21. Ozkurt H, Cenker MM, Bas N, Erturk SM, Basak M. Endosc. Mar 2003;57(3):387. Measurement of the distance and angle between the aorta and 45. Unal B, Aktas A, Kemal G, et al. Superior mesenteric artery syn- superior mesenteric artery: normal values in different BMI cat- drome: CT and ultrasonography findings. Diagn Interv Radiol. egories. Surg Radiol Anat. Oct 2007;29(7):595-599. Jun 2005;11(2):90-95. 22. Strong EK. Mechanics of arteriomesentric duodenal obstruc- 46. Konen E, Amitai M, Apter S, et al. CT angiography of supe- tion and direct surgical attack upon etiology. Ann Surg. Nov rior mesenteric artery syndrome. AJR Am J Roentgenol. 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Arch Orthop Trauma Surg. syndrome complicating dialysis patients with peritoneal failure 1981;98(1):7-11. – report of 3 cases. Clin Nephrol. Feb 2011;75 Suppl 1:37-41. 32. Schwartz A. Scoliosis, superior mesenteric artery syndrome, and adolescents. Orthop Nurs. Jan-Feb 2007;26(1):19-24; quiz 25-16. 33. Zhu ZZ, Qiu Y. Superior mesenteric artery syndrome follow- ing scoliosis surgery: its risk indicators and treatment strategy. World J Gastroenterol : WJG. Jun 7 2005;11(21):3307-3310. REPRINTS 34. Altiok H, Lubicky JP, DeWald CJ, Herman JE. The superior mesenteric artery syndrome in patients with spinal deformity. Special rates are available for Spine (Phila Pa 1976). Oct 1 2005;30(19):2164-2170. quantities of 100 or more. 35. Tsirikos AI, Jeans LA. Superior mesenteric artery syndrome in For further details visit our website: children and adolescents with spine deformities undergoing cor- rective surgery. J Spinal Disord Tech. Jun 2005;18(3):263-271. www.practicalgastro.com 36. Braun SV, Hedden DM, Howard AW. Superior mesenteric artery syndrome following spinal deformity correction. J Bone Joint

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