Nutcracker Syndrome
Nutcracker syndrome (NCS) represents a constellation of symptoms caused by extrinsic compression of the left renal vein (LRV) by surrounding anatomic structures (most commonly between the aorta and the overlying superior mesenteric artery (SMA)) or by stretching and traction on the LRV, with consequent reduction of the LRV outflow. The most frequent presenting symptoms are microscopic or gross hematuria and left flank pain. In advanced stages, pelvic congestion develops with concomitant lower extremity, posterior thigh, and/or gluteal varicosities, varicocele in men (typically left-sided), as well as vulvar/labial varices in females. Currently there is no gold standard diagnostic modality, and diagnosis is most commonly achieved through dedicated clinical examination and characteristic findings on cross-sectional imaging and venography. In certain cases, LRV compression is diagnosed incidentally when no symptoms are present; this is referred to as “nutcracker phenomenon.” A decision to intervene is based on a combination of clinical presentation, radiologic findings and patients’ preference and is recommended in symptomatic patients only. Traditionally, treatment modalities consisted of surgical procedures such as LRV transposition or vein bypass, that were associated with relatively high efficacy and acceptable complication rates. Endovascular treatment with LRV stenting has been successfully introduced relatively recently, although no long-term outcomes data are available for more accurate assessment of endovascular approach. In the proximal future, it is reasonable to expect that development of dedicated venous stents will result in expansion of endovascular treatment modalities in the management of NCS patients.
