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A 27-year-old man presents to a Radiodiagnostic and Radiotherapy Unit in Catania, Italy, for investigation of rapid weight loss. He reports that he has lost 10 kg in the past 3 months; his only other symptom is pain in his upper abdomen after eating.

The patient is underweight, with a body mass index of 17.37 (height is 1.75 m, weight is 63 kg).

Clinicians perform an ultrasound examination with B-mode, color, power, and duplex Doppler of the abdomen, using an Aplio XG (Toshiba) ultrasound device, with a 3.5 MHz convex and a 7.5 MHz linear probe.

Ultrasound findings include the following:

• Reduced aorto-mesenteric angle (18°), measured at the origin, and aorto-mesenteric distance (7 mm) measured at 2 cm from the origin

• Compression of the left renal vein between the superior mesenteric artery and aorta (diameter <3 mm)

• Left renal vein diameter of about 11 mm scan, and a maximum speed of about 12.1 cm/s (scan performed at the renal hilum)

• Scans performed in the pampiniform plexus reveal the presence of left varicocele

The patient's varicocele is not producing any clinical symptoms such as pain in the groin, lumbar, or testicles, nor is there any testicular swelling. Likewise, laboratory tests show no evidence of hematuria or proteinuria.

A subsequent computed tomography (CT) examination is performed and excludes side pathologies. Findings confirm compression of the duodenum (Wilkie syndrome) and compression of the left renal vein ("nutcracker syndrome").

Clinicians place an endovascular stent in the left renal vein. At that point, the ultrasound shows an increased aorto-mesenteric angle (56°), patency of the stent with a maximum flow of 15.1 cm/s, caliber reduction (11 mm), and in­creased flow (29.9 cm/s) of the left renal vein, as well as varicocele regression. In the following days, the patient's postprandial pain gradually decreases.

Discussion

Clinicians reporting this of a patient with both Wilkie syndrome and nutcracker syndrome explain that the case is notable for the combination of these two rare syndromes and the unusual symptoms that resulted, and that ultrasound examination was key to making the diagnosis of nutcracker syndrome.

These two rare vascular pathologies are caused by an anomalous course of the superior mesenteric artery such that, at the origin, it presents angulations with the abdominal aorta of less than 22 degrees and a distance between that and the aorta of less than 8 mm.

In nutcracker syndrome, the reduced aorto-mes­enteric angle compresses the left renal vein, resulting in congestion of the venous outflow from the left kidney and consequent varicocele. In Wilkie syndrome, also known as superior mesenteric artery syndrome, the reduced aorto-mesenteric angle and reduced aorto-mesenteric distance causes duodenal compression resulting in sub-occlusive crisis, vomiting, and postprandial pain.

The syndrome may be congenital but is more frequently acquired. The latter form usually develops after rapid weight loss causes a reduction of the fat surrounding the abdominal aorta and superior mesenteric artery. Thus, the risk is increased in people with anorexia, and in those with other conditions that result in rapid or significant weight loss, such as excessive exercise and gastric bypass surgery.

Other include spinal cord injury, abdominal trauma or surgery (e.g., surgery for scoliosis in younger patients), certain cancers, aortic aneurysm, chronic inflammation, and extensive burns that have resulted in fat and muscle wasting.

Symptoms

Symptomatology is non-specific and is shared by many other abdominal pathologies; the most frequent signs are belching, abdominal fullness, postprandial pain, biliary re­flux, and biliary vomiting and nausea. The nature of symptoms depends on the degree of duodenal obstruction -- i.e., mild obstruction may cause only epigastric pain after meals, while more significant blockage can result in weight loss, nausea, and bilious vomiting.

Authors of one noted that symptoms of nutcracker syndrome are often aggravated by physical activity, with hematuria as the most common symptom, followed by pain, which is often worsened by sitting, standing, walking, or vibrations, such as due to a bumpy ride in a vehicle. Additionally, gonadal vein syndrome is characterized by abdominal or flank pain that occasionally radiates to the back of the thigh and buttock. Other symptoms include varicocele, orthostatic proteinuria, orthostatic intolerance, and chronic fatigue.

Diagnosis

Nutcracker syndrome is best diagnosed with ultrasound; this highly sensitive diagnostic modality allows clinicians to measure the angle and aorto-mesenteric distance, evaluate the degree of congestion of the left renal vein, and assess for the left varicocele. Ultrasonographic diagnostic criteria are standardized and well described in the literature, the case authors note.

Ultrasound has many advantages, including the absence of ionizing radiation and its repeatability and low cost. Ultrasound, however, does not allow a complete diagnostic assessment, since the study of duodenal compression must be used in conjunction with other methods such as magnetic resonance enterography, fluoroscopy, and endoscopy. Ultrasound may not be an effective diagnostic approach in patients with elevated intestinal meteorism; in these cases, a CT scan allows clinicians to assess both vascular alterations and duodenal compression.

In this patient's case, nutcracker syndrome was diagnosed based on the ultrasound finding of an aorto-mesenteric angle reduction (less than 22°) and an aorto-mesenteric distance reduction (less than 8 mm), associated with flow congestion in the left renal vein with consequent left varicocele. The diagnosis of Wilkie syndrome was made based on CT evidence of stenosis of the third distal duodenum.

The case authors note that their patient's presentation with intense postprandial pain and without vomiting was unusual, given that the syndrome almost always presents with an emetic crisis. Still, there have been other cases with similar symptoms, although with associated dyspepsia. As a result of the unusual presentation, the range of diagnostic hypotheses was broad, and included pancreatitis, gastritis, gastric ulcer, duodenal ulcer, cholelithiasis, hiatal hernia, diverticulitis, and gastroesophageal reflux.

Treatment

Conservative treatment with a high-calorie diet is the preferred approach, and may be sufficient when symptoms are mild. Weight gain can restore the normal layer of perivascular adipose tissue and normal angulation of the aorto-mesenteric angle.

More severe cases may require surgical treatment and endovascular stenting. The elective surgical treatment consists of resection of the first duodenal loop and retrovascular duodenum and in the pack­aging of the anastomosis between the duodenum and the second duodenal loop, which are carried anteriorly.

Endovascular stenting involves placement of a stent in the left renal vein to correct the aorto-mesenteric angle and restore regular flow.

If a high-calorie diet fails to restore a normal aorto-mesenteric angle, the next best option is the interventional procedure, which is less invasive, less expensive, and involves a shorter hospital stay compared with surgery, the case authors note. However, due to the complications of endovascular stenting, especially the migration and occlusion of the stent, controversies still exist about the optimal treatment.

The case clinicians conclude that based on this experience, assessment of patients with weight loss and postprandial pain should be extended to the examination of the aorto-mes­enteric angle to confirm or exclude any vascular compression.

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