What is the diagnosis and treatment for Nutcracker syndrome (left renal vein compression)?

From the Guidelines

Percutaneous endoluminal left renal vein stenting is the preferred treatment for nutcracker syndrome due to its lower morbidity compared to surgical techniques. Nutcracker syndrome is a vascular compression disorder where the left renal vein becomes compressed between the abdominal aorta and superior mesenteric artery, causing increased pressure in the left renal vein. This compression leads to symptoms including flank pain, blood in the urine (hematuria), pelvic congestion in women, and varicoceles in men. Treatment depends on symptom severity, with mild cases often managed conservatively through weight gain to increase fat padding around the vessels, adequate hydration, and pain management. For moderate to severe cases, interventional approaches may be necessary, including endovascular stenting of the left renal vein, as supported by recent studies 1.

Some key points to consider in the management of nutcracker syndrome include:

• The use of percutaneous endoluminal left renal vein stenting as a preferred treatment option due to its minimally invasive nature and lower morbidity compared to open surgical techniques 1.
• The importance of individualizing treatment decisions based on symptom severity and impact on quality of life, as symptoms may worsen or improve over time.
• The role of diagnostic imaging, such as Doppler ultrasound, CT angiography, or MR angiography, in visualizing the compression and measuring pressure gradients across the renal vein.
• The potential benefits of surgical transposition of the left renal vein or bypass procedures in select cases, although these approaches are generally associated with higher morbidity 1.

Overall, the management of nutcracker syndrome requires a multidisciplinary approach, taking into account the patient's symptoms, medical history, and individual preferences, with the goal of improving quality of life and reducing morbidity and mortality.

From the Research

Definition and Diagnosis of Nutcracker Syndrome

• Nutcracker syndrome (NCS) is an extrinsic compression of the left renal vein (LRV) by the superior mesenteric artery (SMA) anteriorly and aorta posteriorly, resulting in renal vascular congestion manifesting as hematuria, proteinuria, orthostatic hypotension, pain, or even renal dysfunction 2.
• Diagnosis can be challenging and variable, frequently involving a combination of ultrasound Doppler, cross-sectional, and invasive imaging 2.
• Intravascular pressure measurements are often required to prove a renocaval pressure gradient to aid in a definitive diagnosis 2, 3.

Clinical Manifestations

• NCS can manifest with symptoms such as hematuria, flank pain, pelvic varicosities, or chronic pelvic congestion related to left renal vein (LRV) compression 4.
• Long-standing venous compression can encourage collateral drainage pathways through gonadal and pelvic veins, which may explain reported symptom and syndrome overlap with pelvic congestion syndrome 2.

Management and Treatment

• Conservative management is appropriate, especially in children, who tend to outgrow the disorder 2.
• Medical management with angiotensin converting enzyme inhibitors (ACEIs) is a useful therapy to manage orthostatic hypotension in the pediatric population 2.
• In adults, invasive therapies are more frequently pursued, aimed at relieving the extrinsic compression on the LRV 2.
• The standard of care is renal vein transposition, with renal autotransplantation reserved for recalcitrant cases 2, 5.
• Endovascular stenting is a less invasive option, providing encouraging results with good midterm patency rates and symptom relief 4, 5.
• Laparoscopic placement of an exovascular stent is a newer therapy intended to minimize trauma to the LRV 2.

Outcomes and Follow-up

• Symptom resolution was classified as complete, partial, and none on the basis of the interpretation of medical records on clinical follow-up, with 72.2% of patients having symptoms resolved or improved 4.
• Two-year primary and primary assisted patency was 85.2% and 100%, respectively, with no stent migration occurring 4.
• Long-term follow-up with scheduled ultrasound examinations should be maintained, especially in young patients 6.