Fact-sheet: Superior mesenteric artery syndrom
Updated on 09/17/2021 at 12:16 PM
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Definition
-Digestive compression:
Extrinsic and intermittent compression of the third portion of the duodenum (D3) between the superior mesenteric artery and the aorto-spinal plane.
Aorto-mesenteric pincer: fatty cellular space located between the aorta and the SMA. Contains D3, and sometimes the SMV, which may cross the SMA at this level.
Predisposing factors:
-changes in lordosis (spinal trauma and surgery, brace wear)
-anatomic: hypertrophy of the ligament of Treitz, short ligament of Treitz
-thinness (post-sleeve, prolonged ICU stay, anorexia nervosa)
-other: mesenteric lymphadenopathy, AAA
-Vascular compression:
Compression of the left renal vein in the aorto-mesenteric pincer (anterior nutcracker) or between the aorta and the vertebral body (posterior nutcracker)
definition: hilar renal vein diameter/pincer renal vein diameter >5
Clinical features
Acute form: rare, severe high obstruction chronic form: 90% of cases, nonspecific and intermittent digestive symptoms, epigastric pain, bilious vomiting, nocturnal in the supine position, relieved by sitting up and left lateral decubitus -vascular compression: asymptomatic microscopic hematuria, macroscopic hematuria, abdominal or left flank pain sometimes accompanied by nausea or vomiting, orthostatic proteinuria. Reflux into the left gonadal vein may sometimes induce a pain syndrome exacerbated by sitting or standing: pelvic congestion syndrome in women, often associated with pelvic varices with dyspareunia, dysuria, dysmenorrhea, and left varicocele with testicular pain in men.
Radiography
Upper GI series: duodenal dilation, linear cutoff of contrast material at the level of D3
Ultrasound
Dilation of D2, preserved peristalsis, reduced space between the SMA and the aorta
CT
Reduced aorto-mesenteric space:
-distance <8 mm at the level of D3 (mean distance between the aorta and the SMA at the level of D3 passage, measured in the axial and oblique sagittal planes),
-aorto-mesenteric angle <20° (angle of the SMA origin in a sagittal plane)
Management
Treatment:
-medical first-line: parenteral or enteral nutritional support
-surgical for refractory forms: in children (Strong's procedure): division of the ligament of Treitz to lower D4, or internal bypass such as duodenojejunostomy
-treatment of vascular compression:
.ACE inhibitors
.Depending on symptoms, transposition of the left renal vein or the superior mesenteric artery
.Nephrectomy