Spontaneous dissection of the superior mesenteric artery (SMA) is a rare condition. Here we report 2 cases of spontaneous SMA dissection causing acute abdomen. Bowel infarction did not occur in either case despite total occlusion or severe stenosis of the SMA;we successfully managed isolated SMA dissection without surgical intervention. Our nonoperative management regimen for spontaneous SMA dissection consisted of intestinal rest with fasting, administration of a vasodilator, and blood pressure control. Surgical intervention should be unnecessary unless complications, such as intestinal infarction and abdominal angina, occur.</p

Ishida, Atsuhisa

Kuinose, Masahiko

Tamaki, Takahiko

Totsugawa, Toshinori

Tsushima, Yoshimasa

Yoshitaka, Hidenori

Okayama University Scientific Achievement Repository

Acta Medica OkayamaVolume 63, Issue 3 2009 Article 6JUNE 2009Spontaneous dissection of the superiormesenteric artery as a rare cause of acuteabdomen:report of two casesToshinori Totsugawa∗ Masahiko Kuinose† Atsuhisa Ishida‡Takahiko Tamaki∗∗ Hidenori Yoshitaka†† Yoshimasa Tsushima‡‡∗Department of Cardiovascular Surgery, The Sakakibara Heart Institute of Okayama,†Department of Cardiovascular Surgery, The Sakakibara Heart Institute of Okayama,‡Department of Cardiovascular Surgery, The Sakakibara Heart Institute of Okayama,∗∗Department of Surgery, The Sakakibara Heart Institute of Okayama,††Department of Cardiovascular Surgery, The Sakakibara Heart Institute of Okayama,‡‡Department of Cardiovascular Surgery, The Sakakibara Heart Institute of Okayama,Copyright c©1999 OKAYAMA UNIVERSITY MEDICAL SCHOOL. All rights reserved.Spontaneous dissection of the superiormesenteric artery as a rare cause of acuteabdomen:report of two casesToshinori Totsugawa, Masahiko Kuinose, Atsuhisa Ishida, Takahiko Tamaki,Hidenori Yoshitaka, and Yoshimasa TsushimaAbstractSpontaneous dissection of the superior mesenteric artery (SMA) is a rare condition. Herewe report 2 cases of spontaneous SMA dissection causing acute abdomen. Bowel infarction didnot occur in either case despite total occlusion or severe stenosis of the SMA;we successfullymanaged isolated SMA dissection without surgical intervention. Our nonoperative managementregimen for spontaneous SMA dissection consisted of intestinal rest with fasting, administrationof a vasodilator, and blood pressure control. Surgical intervention should be unnecessary unlesscomplications, such as intestinal infarction and abdominal angina, occur.KEYWORDS: acute abdomen, spontaneous dissection, superior mesenteric artery, nonoperativemanagementSpontaneous Dissection of the Superior Mesenteric Artery  as a Rare Cause of Acute Abdomen: Report of Two CasesToshinori Totsugawaa＊,  Masahiko Kuinosea,  Atsuhisa Ishidaa,  Takahiko Tamakib,   Hidenori Yoshitakaa,  and Yoshimasa TsushimaaDepartments of aCardiovascular Surgery,  and bSurgery,   The Sakakibara Heart Institute of Okayama,   Okayama 700ﾝ0823,  JapanSpontaneous dissection of the superior mesenteric artery (SMA) is a rare condition.  Here we report 2 cases of spontaneous SMA dissection causing acute abdomen.  Bowel infarction did not occur in either case despite total occlusion or severe stenosis of the SMA; we successfully managed isolated SMA dis-section without surgical intervention.  Our nonoperative management regimen for spontaneous SMA dissection consisted of intestinal rest with fasting,  administration of a vasodilator,  and blood pressure control.  Surgical intervention should be unnecessary unless complications,  such as intestinal infarction and abdominal angina,  occur.Key words: acute abdomen,  spontaneous dissection,  superior mesenteric artery,  nonoperative managementpontaneous dissection of the superior mesen-teric artery (SMA) is a rare condition.  The etiology and natural history of spontaneous SMA dis-section have not been well studied because of the scarcity of reported cases.  However,  the development of diagnostic imaging technology has led to an increased number of reports,  including mild and asymptomatic cases [1ﾝ3].  It is possible that many patients with isolated SMA dissection have been overlooked in the treatment of acute abdomen due to lack of recognition.  Here,  we report 2 cases of spon-taneous SMA dissection and argue its status as a cause of acute abdomen.Case Reports　 Case 1. A 51-year-old man who had received medication for hypertension experienced a sudden onset of epigastralgia in January 2006.  Although endoscopic examinations revealed no remarkable ﬁnd-ings,  he continued to complain of persistent abdominal pain.  He was diagnosed as having isolated SMA dis-section by computed tomography (CT) scan and was transferred to our hospital 2 weeks after symptomatic onset.  On admission,  the patient presented persistent abdominal discomfort with mild pain.  His heart rate was 64beats/min,  and his blood pressure was 150/90mmHg.  Physical examination revealed no peritoneal irritation,  and a vascular bruit was audible above the navel.  Laboratory investigations produced no signiﬁcant ﬁndings except for liver dysfunction due to chronic hepatitis.  An enhanced CT scan revealed spontaneous SMA dissection beginning approximately 2cm from the ostium and a partially thrombosed false SActa Med.  Okayama,  2009Vol.  63,  No.  3,  pp.  157ﾝ160CopyrightⒸ 2009 by Okayama University Medical School.Case Report http ://escholarship.lib.okayama-u.ac.jp/amo/Received November 14, 2008 ; accepted January 29, 2009. ＊Corresponding author. Phone : ＋81ﾝ86ﾝ225ﾝ7111; Fax : ＋81ﾝ86ﾝ223ﾝ5265E-mail : toshinoritotsugawa@mac.com (T. Totsugawa)1Totsugawa et al.: Spontaneous dissection of the superior mesenteric artery as a rarProduced by The Berkeley Electronic Press, 2009lumen that completely compressed the true lumen by 5cm (Fig.  1A).  However,  distal blood ﬂow was pre-served via the mesenteric marginal artery,  and bowel infarction did not occur despite 2 weeks of total occlu-sion of the SMA.  Therefore,  the patient was managed nonoperatively after admission.  A vasodilator,  pros-taglandin E1,  was administered continuously at a dose of 0.02µg/kg/min for 5 days.  Abdominal pain gradu-ally subsided within 1 week,  and the patient was allowed to take foods 11 days after admission.  He was discharged 22 days after admission because his symp-toms were not exacerbated by eating.  Follow-up examinations revealed that the intramural hematoma was completely absorbed and that the caliber of the occluded main trunk of SMA was restored (Fig.  1B,  C).  He remains well without any recurrent symptoms.　 Case 2. A 56-year-old man who had a history of hypertension was admitted to a local hospital in February 2006 with sudden onset of abdominal pain.  A CT scan disclosed isolated dissection of the SMA,  and the patient was subsequently referred to our hospital.  On admission,  his abdominal pain was improved by treatment with analgesics.  His heart rate was 72beats/min,  and his blood pressure was 146/86mmHg.  There were no remarkable ﬁndings on physical examination except for vascular bruit over the epigastrium.  Laboratory tests showed no abnormali-ties.  A CT scan with contrast media revealed a dilated SMA divided into 2 lumina by an intimal ﬂap and an intramural hematoma beginning approximately 1cm from the oriﬁce (Fig.  2A).  A portion of the true lumen of the dissected SMA was highly compressed by a thrombosed false lumen; however,  the mesenteric marginal artery served as a collateral vessel on the distal side of the SMA.  He was treated conserva-tively,  taking into consideration the clinical course of case 1.  A vasodilator,  prostaglandin E1,  was admin-istered continuously at a dose of 0.02µg/kg/min for 4 days.  The patient was allowed to take foods 9 days after admission and did not develop abdominal angina.  158 Acta Med.  Okayama　Vol.  63,  No.  3Totsugawa et al.Fig. 1　 A,  A CT scan after admission showed a dissected false lumen of the SMA compressing the true lumen (arrows) and complete obstruction of the SMA for 5cm (double arrow line and slice 4).  There was a dilated mesenteric marginal artery originating proximal to the occlusion (arrowheads),  and distal branches of the SMA were observed via the collateral artery; B,  Three months later,  the thrombosed false lumen was almost completely absorbed; this led to the opening of the main trunk of the SMA (arrowheads and slice 4); C,  A CT scan 18 months after onset demonstrated complete restoration of the SMA trunk with absorption of the thrombosed false lumen (arrow-heads).2Acta Medica Okayama, Vol. 63 [2009], Iss. 3, Art. 6http://escholarship.lib.okayama-u.ac.jp/amo/vol63/iss3/6A CT scan 2 weeks later demonstrated improvement of the narrowing of the true lumen (Fig.  2B).  The patient was discharged 25 days after admission.  A CT scan 10 months after onset revealed absorption of the thrombosed false lumen and restoration of the caliber of the main trunk of the SMA (Fig.  2C).  He continues to be in good condition.Discussion　 Although the etiology of spontaneous dissection of the SMA may include arteriosclerosis,  ﬁbromuscular dysplasia,  congenital connective tissue disorders,  and trauma,  the deﬁnitive cause is unclear in most cases [4].  The clinical symptoms of isolated SMA dissec-tion usually include acute-onset abdominal pain at the epigastrium or,  in some cases,  chronic abdominal pain,  which is sometimes related to food intake.  Additionally,  patients may occasionally be asymptom-atic [1,  2].  Spontaneous SMA dissection used to be diagnosed by angiography; more recently,  CT scans have become the most reliable diagnostic modality.  A previous report demonstrated that increased attenua-tion of the fat around the SMA is a useful ﬁnding even on a thick-section plain CT scan [3].  Contrast-enhanced CT scans should be considered for diﬀeren-tial diagnosis in the case of acute abdomen with such ﬁndings on CT scans.　 There is currently no established guideline for isolated SMA dissection.  Miyamoto et al.  reported that 24 out of 55 patients with spontaneous SMA dis-section were treated conservatively.  Obstruction of the main SMA trunk does not always result in bowel infarction because of the existence of the mesenteric marginal artery.  The distal blood ﬂow can be pre-served if branches located proximal to the stenosis serve as collateral vessels.  In the present cases,  intestinal necrosis did not occur despite total obstruc-tion or severe narrowing of the SMA; furthermore,  the obstructed and narrowed main trunk of the SMA was ﬁnally restored.  These ﬁndings suggest that sur-gical intervention may not be necessary unless compli-159Spontaneous SMA dissectionJune 2009Fig. 2　 A,  A CT scan after admission revealed the dissected SMA (arrows).  A portion of the true lumen was severely compressed by the thrombosed false lumen (slice 3),  and the mesenteric marginal artery acted as a collateral vessel for the distal side of the SMA (arrowheads); B,  Two weeks later,  the intramural hematoma was mildly resolved with dilatation of the SMA trunk (slice 3); C,  A CT scan 10 months after onset demonstrated complete restoration of the SMA trunk with absorption of the thrombosed false lumen (arrows).  A por-tion of the main trunk of the SMA showed a slight aneurysmal dilatation,  which will require careful follow-up (slice 3).3Totsugawa et al.: Spontaneous dissection of the superior mesenteric artery as a rarProduced by The Berkeley Electronic Press, 2009cations such as intestinal infarction and abdominal angina occur.  Our nonoperative management regimen for spontaneous SMA dissection consisted of the fol-lowing elements: conﬁrmation of the existence of mesenteric collateral vessels on CT angiography;  intestinal rest with fasting; administration of a vaso-dilator,  such as prostaglandin E1,  until the patientʼs symptoms subside; and blood pressure control to a systolic blood pressure of around 120mmHg.  We should also recognize that surgical intervention is necessary in the presence of the following indica-tions: bowel infarction or aneurysmal rupture of a dissected SMA in the acute phase,  persistent symp-toms refractory to conservative therapy in the sub-acute phase,  and enlargement of a dissecting aneurysm or abdominal angina accompanying food intake in the chronic phase [5].  Recently,  endovascular stenting has been reported as a treatment for SMA dissection [4,  6].  Endoluminal intervention is obviously less invasive than open surgery unless intestinal infarction occurs; endovascular stenting may become a valuable option for mesenteric revascularization in the near future.　 We conclude that isolated SMA dissection should be recognized as a cause of acute abdomen and that conservative therapy should ﬁrst be taken into consid-eration.  Accumulation of further information is indispensable for establishment of an optimal manage-ment regimen for spontaneous SMA dissection.References 1. Nakamura K,  Nozue M,  Sakakibara Y,  Kuramoto K,  Satoh M,  Kobayashi S,  Kashimura H,  Fukutomi H,  Todoroki T and Fukao K: Natural history of a spontaneous dissecting aneurysm of the proximal superior mesenteric artery: report of a case.  Surg Today (1997) 27: 272ﾝ274. 2. Hyodoh H,  Hyodoh K,  Takahashi K,  Yamagata M and Kanazawa K: Three-dimensional CT imaging of an isolated dissecting aneu-rysm of the superior mesenteric artery.  Abdom Imaging (1996) 21: 515ﾝ516. 3. Suzuki S,  Furui S,  Kohtake H,  Sakamoto T,  Yamasaki M,  Furukawa A,  Murata K and Takei R: Isolated dissection of the superior mesenteric artery: CT ﬁndings in six cases.  Abdom Imaging (2004) 29: 153ﾝ157. 4. Miyamoto N,  Sakurai Y,  Hirokami M,  Takahashi K,  Nishimori H,  Tsuji K,  Kang JH and Maguchi H: Endovascular stent placement for isolated spontaneous dissection of the superior mesenteric artery: report of a case. Radiat Med (2005) 23: 520ﾝ524. 5. Sparks SR,  Vasquez JC,  Bergan JJ and Owens EL: Failure of nonoperative management of isolated superior mesenteric artery dissection Ann Vasc Surg (2000) 14: 105ﾝ109. 6. Froment P,  Alerci M,  Vandoni RE,  Bogen M,  Gertsch P and Galeazzi G: Stenting of a spontaneous dissection of the superior mesenteric artery: a new therapeutic approach? Cardiovasc Intervent Radiol (2004) 27: 529ﾝ532.160 Acta Med.  Okayama　Vol.  63,  No.  3Totsugawa et al.4Acta Medica Okayama, Vol. 63 [2009], Iss. 3, Art. 6http://escholarship.lib.okayama-u.ac.jp/amo/vol63/iss3/6

Spontaneous dissection of the superior mesenteric artery as a rare cause of acute abdomen:report of two cases

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