Nutcracker phenomenon or nutcracker syndrome?
Sir,Liebl R [1] commented on the difference in definitions of nutcracker phenomenon and nutcracker syndrome: nutcracker phenomenon, asymptomatic dilatation of the left renal vein, should be differentiated from nutcracker syndrome, presenting with gross or microscopic haematuria, orthostatic proteinuria, varicocele and hypertension. In previous papers, however, these two terms have been used together in patients with clinical symptoms. Also, asymptomatic dilatation of the left renal vein frequently shown on two-dimensional ultrasound or computed tomography has been regarded as a finding of a normal variant [2]. Furthermore, Takebayashi et al. [3] demonstrated that nutcracker syndrome can exist even in non-distended left renal veins, and normal flow also can exist in distended left renal veins. Therefore, nutcracker phenomenon or syndrome should be defined only when the clinical symptoms are present along with compatible radiologic findings, although the terminology, ‘nutcracker’ itself means the anatomical compression of the left renal vein between the superior mesenteric artery and the aorta.
Furthermore, Liebl [1] cited that patients with nutcracker phenomenon are usually young and slim. Although our previous report [4] suggested that changes of body mass index in children with nutcracker syndrome might influence the aortomesenteric angle, there has been no report describing the relationship between nutcracker syndrome and physical characteristics. Therefore, further anthropometric studies should be performed to identify these associations.
Conflict of interest statement. None declared.
The Institute of Kidney Disease Department of Paediatrics Yonsei University College of Medicine Seoul Korea Email: jsyonse{at}yumc.yonsei.ac.kr
References
- Liebl R. Nutcracker phenomenon or nutcracker syndrome? Nephrol Dial Transplant 2005; doi:10.1093/ndt/gfh917
- Zerin JM, Hernandez RJ, Sedman AB, Kelsch RC. Dilatation of the left renal vein on computed tomography in children: a normal variation. Pediatr Radiol 1991; 21: 267–269[Medline]
- Takebayashi S, Ueki T, Ikeda N, Fujikawa A. Diagnosis of the nutcracker syndrome with color Doppler sonography: correlation with flow patterns on retrograde left renal venography. Am J Roentgenol 1999; 172: 39–43
[Abstract/Free Full Text] - Shin JI, Park JM, Lee SM et al. Factors affecting spontaneous resolution of hematuria in childhood nutcracker syndrome. Pediatr Nephrol 2005 May; 20: 609–613[Medline]
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