A Model Example: Coexisting Superior Mesenteric Artery Syndrome and the Nutcracker Phenomenon

Abstract

Superior mesenteric artery (SMA) syndrome is a rare cause of gastrointestinal obstruction, caused by external compression of the third part of the duodenum by the SMA. It may be associated with the Nutcracker phenomenon: external compression of the left renal vein. To our knowledge, there are few reports in the literature describing the coexistence of these two conditions and so we take this opportunity to highlight a rare cause of the acute abdomen that might otherwise be overlooked in cases of nonspecific abdominal findings and potentially unremarkable initial investigations. We report a case of SMA syndrome and Nutcracker phenomenon in a 19-year-old female who presented to our emergency department with a short history of epigastric pain and emesis. The SMA syndrome is thought to develop as the result of an abnormally narrow angle between the proximal SMA and the aorta, for which a number of predisposing factors have been described. Surgical options exist; however, the SMA syndrome is typically managed conservatively in the first instance, consistent with the approach described in this case. The Nutcracker phenomenon may give rise to the Nutcracker syndrome in the presence of typical clinical manifestations; however, these did not feature in this case.

A Rare Case of Coexisting Superior Mesenteric Artery Syndrome and Nutcracker Phenomenon

“…2 A significantly decreased AMD of 3 mm and decreased AA of <15 degrees has been previously reported in patients with nutcracker syndrome. [2][3][4] A decreased AA may be due to rapid weight loss resulting in reduced fat and lymphatic tissue at the origin of the SMA, decreasing the ability to cushion the duodenum and protect it from compression. 2,3 In the current case, the patient's significant weight loss, particularly of intra-abdominal fat, was thought to be a contributing factor to the unusual vascular compression of the duodenum.…”

“…Other factors can include anatomical abnormalities such as a short ligament of Treitz, pressure from external sources such as body casts and postoperative complications from procedures such as abdominal aortic aneurysm repairs, scoliosis surgeries, ileo-anal pouch anastomoses and total proctocolectomies. 3,4 For most patients with SMA syndrome, conservative management-including the correction of electrolyte imbalances along with appropriate enteral or parenteral nutrition-usually results in sufficient weight gain and symptomatic improvement. 3 Surgical procedures such as a duodenojejunostomy or the surgical release of the Treitz ligament are reserved for cases which do not respond to conservative treatment.…”

“…3 Surgical procedures such as a duodenojejunostomy or the surgical release of the Treitz ligament are reserved for cases which do not respond to conservative treatment. [2][3][4] Nutcracker phenomenon refers to the compression of the left renal vein between the SMA and the abdominal aorta.…”

“…4 Although the terms 'nutcracker syndrome' and 'nutcracker phenomenon' are sometimes used interchangeably, some symptoms may be unassociated and certain anatomical findings may represent a normal variant; hence, the term 'nutcracker syndrome' should be reserved for patients with characteristic clinical symptoms associated and demonstrable morphological features. [2][3][4] Besides the classic (i.e. anterior) nutcracker syndrome, other anatomical variants have been described.…”

“…anterior) nutcracker syndrome, other anatomical variants have been described. 4,5 Posterior nutcracker syndrome involves compression of the left renal vein between the abdominal aorta and vertebral spine, whereas combined nutcracker syndrome refers to a duplication of the vein causing compression of either the anterior branch between the abdominal aorta and SMA or posterior branch between the abdominal aorta and haematuria and a second clinical examination did not reveal any left-sided varicoceles.…”