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Abstract
Aim Superior mesenteric artery (SMA) syndrome is a rare condition whereby external compression of the third part of the duodenum by the SMA results in duodenal obstruction. Nutcracker phenomenon refers to compression of the left renal vein by the SMA, an isolated radiological finding, with potential clinical manifestations such as left flank pain, haematuria, and left-sided varicocele. We describe very rare presentation of SMA syndrome with coexisting Nutcracker phenomenon in a child.
case presentation A 11-year-old male complaining of postprandial epigastric pain, emesis, anorexia and weight loss over two years. There was an absence of any previous medical or psychiatric diagnoses and no previous abdominal surgery.
Physical examination revealed an underweight and pale patient. The patient was clinically stable and abdominal examination revealed a soft abdomen with epigastric tenderness. Initial blood test results were unremarkable: white cell count, 9.6×109/L (4.2–11.2); C-reactive protein, 1 mg/L; haemoglobin, 135 g/L (114–150); sodium, 139 mmol/L (133–146); potassium, 4.1 mmol/L (3.5–5.3); eGFR, 83 mL/min (MDRD formula); amylase, 56 IU/L; lactate, 2.2 mmol/L (0.6–2.5); albumin, 2.9 g/dl. Urinalysis was negative for blood, leukocytes, and nitrites, but protein positive.
The disparity between the patient‘s clinical appearance, biochemical results, and initial imaging gave cause for clinical concern, and so the patient underwent a contrast enhanced computerised tomography (CT) scan. The CT scan revealed a grossly distended stomach, dilated proximal duodenum, and a narrowing of the third part of the duodenum between the angle of the superior mesenteric artery and abdominal aorta. There was also narrowing of the left renal vein underlying the superior mesenteric artery. A diagnosis of SMA syndrome with coexisting Nutcracker phenomenon was made.
Gastric decompression was instituted with a nasogastric tube insertion. Nutritional support was initially provided through combined TPN (total parenteral nutrition) and enteral means. Results of further investigations included an oesophagealgastroduodenoscopy which showed a normal duodenal cap and second part of the duodenum and a barium meal and follow through study with findings consistent with the diagnosis of SMA syndrome (Figur1-2).
Conclusion SMA syndrome is a rare cause of upper gastrointestinal obstruction. It may be associated with the Nutcracker phenomenon, with or without its own clinical manifestations. Clinicians should be aware of this diagnosis and consider it in cases of abdominal pain that are not in proportion to biochemical or clinical findings.
Figure 1 Axial CT section demonstrating the anatomy of Nutcracker phenomenon and SMA syndrome.
Figure 2 Barium study showing dilated proximal part and narrowed third part of duodenum.