Teaching Case

A 72-year-old male without any known past abdominal surgery, presented to the emergency department with mild-to-moderate left-sided abdominal pain, nausea, and a single episode of vomiting. The pain was severe enough to wake him up and worsened after eating lunch. The patient was afebrile and had normal vital signs.

Abdominal contrast-enhanced CT scan in the portal venous phase showed a large retroperitoneal hematoma in the epigastric region that on the right side is extended along the caudate part of the right liver lobe and on the left side to the left hypochondrium, without any sign of active bleeding (Figures 1a, 1b). In addition, a "Hooked" shaped Celiac artery was shown as a result of stenosis in the root and post-stenotic dilatation of the artery (Figure 1c). Subsequent CT angiography confirmed Median Arcuate Ligament Syndrome (MALS)  and showed aneurysmal dilatation in the celiac and pancreaticoduodenal arteries (Figures 2a, 2b).

Background

Median arcuate ligament syndrome (MALS) occurs when the central fibrous band of the diaphragm (MAL), which attaches to the right and left crura, crosses over and compresses the celiac artery base. This results in characteristic radiographic and clinical features. Stenosis of the celiac artery increases the compensatory blood flow in the collaterals between the superior mesenteric artery (SMA) and the celiac artery (such as the pancreaticoduodenal artery/gastroduodenal artery/dorsal pancreatic artery), which indicates a higher risk of aneurysm, dissection, and rupture in these collaterals and intra-abdominal bleeding [1, 2, 3].

Clinical Perspective

Symptoms of the syndrome consist of postprandial abdominal pain, nausea, vomiting, and weight loss [7]. In the case of subsequential retroperitoneal bleeding, the most common presentation is abdominal or flank pain with or without radiation into the groin or pelvis. Progression of retroperitoneal bleeding can lead to anxiety and tachycardia in the early phase and hypotension, confusion, and hypothermia later. Physical examination, in some cases, may demonstrate a palpable abdominal mass [4].

Imaging Perspective

CT angiography with the possibility of 3D reconstruction is the modality of choice for diagnosing MALS and celiac artery dissection; however, MR angiography, sonography, and conventional angiography can also be used [6]. 3D reconstruction of CT angiography shows a “hooked” appearance, which is characteristic of median arcuate ligament syndrome. The hook sign is composed of a combination of the pressure point of the MAL and post-stenotic dilatation of the celiac artery. In about 10-24% of the population, the ligament may cross the proximal portion of the celiac axis without any clinical symptoms [5].

Outcome

Endovascular aneurysm embolization is the first-choice treatment for visceral aneurysms [6]. Subsequently, the median arcuate ligament (MAL) should be incised to prevent the recurrence of the aneurysm and the risk of adhesive bowel obstruction [8]. Laparotomy, laparoscopic surgery, and retroperitoneal endoscopic surgery have been reported [8].

In our case, interventional radiology was consulted, and the pancreaticoduodenal artery was coil-embolized (Figures 3, 4). A control CT angiography of the abdomen after 3 months showed the coil-embolized pancreaticoduodenal artery without any flow or leakage. The patient is referred to surgeons for MAL treatment with laparoscopy or open surgical decompression of the celiac trunk to prevent the reformation of compression, but the patient refused because he means that all his symptoms had disappeared after the primary interventional treatment.

Take Home Message / Teaching Points

The above case is a reminder to consider MALS as one of the differential diagnoses of retroperitoneal hematoma in a patient who develops sudden onset postprandial abdominal pain, nausea, and vomiting with vital signs within the normal range.