Secondary vascular alterations in nutcracker phenomenon and its variants on multidetector CT

Objectives: Nutcracker phenomenon is caused by the compression of left renal vein between the superior mesenteric artery and the aorta. There are also variants namely the ‘posterior nutcracker phenomenon’ where the posteriorly located retroaortic or circumaortic left renal vein is compressed between the aorta and the vertebral body. The aim of this  study is to define vascular alterations in veins other than the left renal vein secondary to anterior and posterior nutcracker phenomena and emphasize their contribution to diagnosis.  

Methods: Computed tomography images of 57 patients with nutcracker phenomenon were retrospectively nvestigated fort he presence of secondary vascular alterations. In addition, 169 patients with a retroaortic and  32 patienys with a circumaortic left  renal vein variation were searched for thepresence of a posterior nutcracker phenomenon and associated secondary vascular findings.

Results: Dilatation of left gonadal (n: 15, 26%), left lumbar or ascending lumbar (n: 9, 16%), hemiazygos (n: 4, 7%), left suprarenal (n: 4, 7%), and inferior phrenic (n:2, 4%) veins were seenin anterior nutcracker phenomenon. Pelvic varices/varicoceles pseudothrombosis in the left renal vein were present in 7(12%) and 4 ( 7%) patients, respectively.. There was a appearance in 4 patients. 14 % of 169 patients with a retroaortic left renal vein  and  16 % of 32 patients with circumaortic left renal vein showed a posterior NC phenomenon and associated vascular alterations. 

Conclusions: Awareness of the secondary vascular findings in nutcracker phenomenon may aid in the diagnosis and guide management.