NUTCRACKER SYNDROME: A RARE AND UNDERDIAGNOSED PATHOLOGY ? OUR EXPERIENCE, REVIEW OF THE LITERATURE AND PROPOSAL OF A NEW ANATOMICAL CLASSIFICATION OF NUTCRACKER SYNDROME

Abstract

Objective: Evaluate our experience with treated patients with the diagnosis of Nutcracker Syndrome, literature review and proposal of a new classification for the Nutcracker Syndrome

Introduction: The Nutcracker syndrome (NCS) can result from the left renal vein (LRV) compression between the superior mesenteric artery and the aorta (Anterior NCS), or more rarely by compression of the LRV between the aorta and the lumbar vertebra when the vein passes behind the aorta, (posterior NCS). The association of the two anomalies can occur when a circunaortic renal vein exists. The prevalence of NCS is unknown, but it appears to be rare and under diagnosed.

Methods and Materials: A retrospective descriptive analysis case by case, based on the clinical and imagiological records related to seven patients diagnosed with Nutcracker Syndrome, in the period between January-2011 and March- 2017, in our center . The diagnosis was made by clinical suspicion, after exclusion of other more common etiologies, and the observation of a significant hemodynamic stenosis of the venous kidney drainage by computed tomography. We observed 7 patients, 57,1% (4 patientes) females, with a mean age of 21,7 years with 85,7% in their second or third decade of life. Posterior NCS were observed in 42,9% (3 patients), anterior NCS in 28,6% (2 patients), antero-posterior NCS in 14,3% (1 patient), and compression of a left side vena cava by the aorta when it crosses to right side in 14,3% (1 patient). The most common symptom was macroscopic hematúria (71,4%), followed by flank pain exacerbated by exercise (28,6%) and congestion pelvic syndrome in 14,3%. Tree patients were submitted to surgery, two were treated with a renal auto transplant and one a left ilio-caval stenting. One patient submitted to an auto transplant necessitated a nephrectomy secondary to a renal venous thrombosis. The other four patients followed a conservative management and surveillance. After a mean follow-up of 2,7 years, five patients were asymptomatic, one had a self-limited haematuria episode, and another kept asymptomatic proteinuria.

Discussion/Conclusion: The diagnosis of NCS can be made at any age, particularly in the second and third decade of life and is reported to be more frequent in females. In our experience we observed a female/male ratio of 1,3, and a high proportion of posterior NCS (42,9%). The posterior NCS type was the most common type of NCS, going against the literature that reports only 19 cases since 2017. We describe a fourth type of Nutcracker Syndrome, that we call other anatomic type of NCS and we propose a new anatomical classification of NCS. A policy of wait and see, decreased the necessity of surgery to near one half of the patients (42,9%). The choice of renal auto transplant was due to our long and good experience in kidney transplantation, with more than 2500 cases done. The nephrectomy was done by laparoscopy to reduce the invasiveness, and we should pay attention to the tension of the renal vein, as it can result in thromboses as was one of our cases. Despite the recent reports of good results with stenting of the renal vein, we keep concern about the durability of the stents in this young population and it isn’t our first choice.