Name of journal: World Journal of Nephrology esps manuscript no: 11830 Columns: Minireviews Nutcracker syndrome

TREATMENT

NCS is a type of spectral disease and varies in severity and symptoms, reflecting degrees of LRV compression, LRV hypertension and the compensatory stage related to the development of collaterals^[11]. The management of NCS depends upon the clinical presentation and the severity of the LRV hypertension. The treatment options are ranged from surveillance to nephrectomy. Treatment decision should be based on the severity of symptoms and their expected reversibility with regard to patient’s age and the stage of the syndrome^[27]. Mild and tolerable symptoms can be followed conservatively. However, recurrent gross hematuria with anemia, severe flank pain, renal functional impairment, and inefficacy or aggravation of conservative treatment of the persistent orthostatic proteinuria after 24 mo of follow-up might require surgical treatment^[18].

Spontaneous resolution by physical development during childhood is possible^[18]. Conservative approach with observation during minimum 2 years without medication is the best option for patients younger than 18 years old. Seventy-five percent of patients with hematuria have complete resolution during this time^[7]. Angiotensin inhibitors could be effective in patients with especially severe and prolonged orthostatic proteinuria^[1].

Surgical procedures are used for treatment in patients with severe symptoms. Nephropexy, intravascular and extravascular stent implantation, transposition of the LRV or SMA, gonadocaval bypass, renal autotransplantation and nephrectomy are surgical procedures.

Open surgical techniques for anterior NCS include LRV transposition, LRV transposition with patch venoplasty, patch venoplasty without LRV transposition, LRV transposition with saphenous vein cuff, gonadal vein transposition and saphenous vein bypass^[28]. LRV transposition is the most frequent and most effective technique in which LRV is transposed distally to the IVC. The LRV is transected and re-anastomosed to the IVC in a more distal location and in a tension-free end-to-side fashion. LRV transposition with patch venoplasty is used in conditions as permanent distortion of the vein with prolonged compression of the LRV or overstretched LRV because of the prominent aorta. The great saphenous vein is used as a patch to augment the LRV-IVC confluence after transposition of the LRV. Patch venoplasty without LRV transposition technique is used when transposition is not favorable because of the short renal vein is short or it is not improve the external compression of the vein. In LRV transposition with saphenous vein cuff technique the saphenous vein is used to form a cuff extension to the LRV to create tension-free anastomosis. Decrease of pelvic congestion and decompression of LRV can be obtained by left gonadal vein transposition. Saphenous vein also can be used for the bypass of the decompressed segment of the LRV^[28].

Anterior transposition of LRV is used for posterior variant of NCS. In this technique LRV is excised with a small rim of the caval wall, and transposed to IVC, in a proximal position, via anteaortic routing^[29].

Surgical placement of an external stent to the LRV is another surgical approach to NCS ^[5]. Endovascular stenting is an alternative treatment option. It can be preferred to open surgery because of the long period of renal congestion, additional anastomoses and extensive dissection requirement of the open surgery. Thrombosis, stent migration, fracture and restenosis are the complications of the endovascular stenting but they are rare^[30].