Case Presentation: Our patient is a 75-year-old gentlemen with past medical history notable for prostate adenocarcinoma with bony metastases diagnosed two months prior and managed with docetaxel-leuprolide-abiraterone triple therapy. After his most recent docetaxel infusion, he presented with worsening nausea, without emesis, and decreased oral intake. Since the diagnosis of prostate cancer, he experienced a 15-lb weight loss and intermittent abdominal pain.Physical examination was notable for normal vital signs , and a soft and non-distended abdomen with epigastric tenderness to palpation. Complete metabolic panel and complete blood count laboratory results were stable. CT scan of the abdomen and pelvis revealed a distended duodenum measuring 5.4 cm at the level of the SMA with an aortomesenteric distance of 6.0 mm, suggestive of SMA syndrome. No other acute pathology was noted. The patient did not tolerate nasogastric tube placement for gastric decompression. After goals of care discussion with the patient, general surgery was consulted to place gastrojejunostomy (GJ) tube for decompression and enteral nutrition. The patient tolerated advancement of enteral feeding, did not develop refeeding syndrome, and advanced oral intake. He was discharged home with nutritional support. Despite multiple readmissions over subsequent months for metastatic bone pain, he regained weight and was able to have his GJ tube removed, tolerating oral nutrition without abdominal pain.
Discussion: Superior Mesenteric Artery (SMA) Syndrome is rare, with an estimated incidence between 0.013% and 0.3%. The third portion of the duodenum passes underneath the SMA, between the SMA and the aorta, with a normal angle between the vessels of 38-65°. The mesenteric fat pad, which correlates to body mass index, maintains this space. Loss of mesenteric fat between the SMA and aorta leads to compression of the duodenum and upstream dilation that results in symptoms of nausea, vomiting, and decreased oral intake. Common predisposing risk factors in adults include trauma, severe burns, malabsorptive disorder, eating disorders, and notably in this case, malignancy. Diagnosis is made from imaging that demonstrates duodenal obstruction, a decreased aortomesenteric angle and distance, and, in some cases, anatomical abnormalities such as a low take-off of the SMA.Diagnosis of SMA syndrome requires a high degree of suspicion given that it presents with non-specific symptoms. In patients undergoing treatment for malignancy, symptoms of weight loss, nausea, and decreased oral intake may be attributed to the primary malignant process or chemotherapeutic agents, thereby obscuring this underlying cause. Further evaluation of poorly controlled symptoms should include abdominal imaging, including computed tomography.Early identification of SMA syndrome is critical as patients may require correction of electrolyte abnormalities and hypovolemia or develop severe complications including gastrointestinal obstruction or perforation. If patients respond well to supportive measures, including nutritional support, major surgical intervention, most commonly laparoscopic duodenojejunostomy, is rarely required.
Conclusions: SMA syndrome is a rare condition that presents with non-specific symptoms that may delay diagnosis. However, with early identification and intervention, SMA syndrome has an overall favorable prognosis, and term-limited enteral nutrition support may improve quality of life for patients with advanced malignancy.