Atypical Superior Mesenteric Artery Syndrome in an Elderly Male Without Classic Risk Factors.

Superior mesenteric artery syndrome (SMAS) is a rare cause of proximal intestinal obstruction caused by compression of the distal third portion of the duodenum between the aorta and superior mesenteric artery (SMA) due to loss of mesenteric fat. This is typically seen in younger patients with rapid weight loss or spinal deformity correction. We report an atypical case of SMAS that occurred in an 80-year-old male who presented with progressive nausea, unintentional weight loss over six months, and vomiting. Despite gastrojejunostomy tube placement, symptoms persisted and were complicated by peritonitis as a result of tube migration. Imaging revealed an aortomesenteric distance of 4.2 mm, proximal duodenal dilation, and a narrowed aortomesenteric angle. All of which are consistent with SMAS. This was attributed to gradual mesenteric fat loss from chronic undernutrition. This case highlights that SMAS may occur in elderly patients without rapid weight loss, scoliosis correction, or prior surgery and may present as a chronic rather than acute condition. Clinicians should maintain a high index of suspicion in older adults with unexplained vomiting and gradual weight loss to allow for early diagnosis, prevent procedural complications, and optimize nutritional recovery.