RETURN TO ABSTRACT LISTING


Background
Nutcracker syndrome is a rare vascular compression syndrome with varied and nonspecific presenting symptoms of left flank pain, pelvic pain, hematuria/proteinuria, gonadal varices, nausea, vomiting and weight loss. Patients may present with left renal vein thrombosis. It is a rare condition with exact incidence unknown. There is a slight female predominance and an association with a thin body habitus. It may also occur in conjunction with Superior Mesenteric Artery (SMA) syndrome. Nutcracker syndrome is differentiated from the nutcracker phenomenon based on the presence of characteristic findings without the symptoms. Surgical treatment options include: left renal vein transposition, gonadal vein transposition, SMA transposition, autologous kidney transplantation, nephrectomy. Endovascular treatment options include: endovascular stent graft placement.

Educational Goals / Teaching Points
Discuss the pathophysiology and clinical presentation of nutcracker syndrome. Review the types of nutcracker syndrome: anterior versus posterior. Identify the diagnostic measurements and imaging characteristics of nutcracker syndrome on computed tomography (CT) and ultrasound. Understand the clinical and therapeutic implications of accurately diagnosing nutcracker syndrome. Learn the various surgical and endovascular treatment options and their post-operative appearance on CT and US. Discuss postoperative complications.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Nutcracker syndrome occurs in two different types. Anterior (left renal vein is compressed between the aorta and superior mesenteric artery [SMA]), and posterior (retro aortic left renal vein compressed between the aorta and vertebral body). Key radiographic measurements include (reduced aortic-SMA angle, pressure gradient greater than 3mm Hg on renal venography, compression ratio greater than 2.25 of pre-compressed to compressed left renal vein, elevated left renal vein velocities on doppler ultrasound). Key imaging findings include (collateral vessels and/or gonadal varices). Pictorial review of postsurgical treatments include left renal vein transposition, gonadal vein transposition, and SMA transposition.

Conclusion
Follow up imaging may demonstrate decreased left renal vein pre-compressed diameter. Radiologists should be aware of the different surgical techniques and be readily able to recognize the postoperative imaging features of nutcracker syndrome. There is a higher morbidity associated with open surgical interventions and complications include deep vein thrombosis, retroperitoneal hematoma, paralytic ileus and adhesions resulting in mechanical ileus. More data is needed on long term outcomes for minimally invasive techniques such as endovascular stenting, such as stent migration, stent patency and durability.