P3.N278: When too much weight loss went wrong – Median arcuate ligament syndrome in a teenager after rapid weight loss

Introduction: Teenage patients presenting with abdominal pain, nausea, vomiting, and weight loss pose a diagnostic challenge due to the broad spectrum of potential etiologies. Here, we present a case of a 19-year-old female exhibiting the above symptoms following rapid weight loss, ultimately diagnosed with median arcuate ligament syndrome (MALS).

Case Description: A 19-year-old female with chronic daily marijuana use and a history of obesity presented to the pediatric emergency department (ED) with sharp postprandial abdominal pain accompanied by nausea, vomiting, bloating, diarrhea, and unintentional weight loss of 30 pounds over the last 5 weeks. Previous visits to outside EDs resulted in unremarkable abdominal ultrasound, with diagnoses of gastroenteritis and cannabinoid hyperemesis syndrome made respectively. Despite cessation of marijuana use for the past 2 weeks, symptoms persisted, prompting the ED visit due to oral intolerance.
On presentation, the patient was tachycardic with a heart rate in the 140s and had a body mass index (BMI) of 23.5 kg/m². Physical examination revealed an ill-appearing patient with dry oral mucosa, skin mottling, diffuse abdominal tenderness, and hyperactive bowel sounds. Laboratory examination revealed significant hemoconcentration, electrolyte derangement with hypokalemia and hypochloremia, and acute kidney injury. There was no leukocytosis. Lipase levels and inflammatory markers including CRP and ESR were within normal limits. COVID-19, flu swab, and GI PCR were negative. Urine drug screen was positive for cannabinoids. Further history revealed intentional weight loss over the past year through drastic fasting and increased exercise, resulting in a loss of approximately 150 pounds in one year prior to symptom onset. An abdominal CT was performed, demonstrating thickening of the median arcuate ligament and narrowed celiac axis origin with a J-shaped configuration (Figure 1). Subsequent duplex arterial ultrasound again revealed a hooked/J configuration of the celiac trunk with increased peak systolic velocities and high resistance waveforms, indicative of compression and high-grade stenosis of the celiac artery. A diagnosis of median arcuate ligament syndrome was made.

Discussion: MALS is a rare disorder characterized by compression of the celiac artery by the median arcuate ligament, a fibrous band of the diaphragm. The classic triad of symptoms includes postprandial abdominal pain, weight loss, and sometimes an abdominal bruit. Other associated symptoms include nausea, vomiting, delayed gastric emptying, and diarrhea. Diagnosis typically requires confirmation by vascular imaging and is often one of exclusion. There have been reports associating MALS with rapid weight loss after bariatric surgery. While MALS predominantly affects middle-aged women, our case highlights its occurrence in a teenage patient following rapid weight loss.

Conclusion: Diagnosing MALS in pediatric patients can be challenging due to its rarity and diverse symptomatology. Nevertheless, it is imperative for Med-Peds physicians to consider MALS as a potential diagnosis in young patients presenting with abdominal pain of unclear etiology.