Nutcracker phenomenon and nutcracker syndrome

Abstract

Nutcracker phenomenon refers to compression of the left renal vein, most commonly between the aorta and the superior mesenteric artery, with impaired blood outflow often accompanied by distention of the distal portion of the vein. The nutcracker syndrome (NCS) is the clinical equivalent of nutcracker phenomenon characterized by a complex of symptoms with substantial variations. Depending on specific manifestations, NCS may be encountered by different medical specialists. Although it may be associated with substantial morbidity, the diagnosis of NCS is often difficult and is commonly delayed. Diagnostic and treatment criteria are not well established, and the natural history of NCS is not well understood. We performed an initial review of the literature through MEDLINE, searching from 1950 to date and using the keywords nutcracker syndrome, nutcracker phenomenon, and renal vein entrapment. We performed additional reviews based on the literature citations of the identified articles. We attempted to elucidate clinical relevance of these conditions and their prominent features and to summarize professional experience.

FIGURE 1.

Schematic representation of nutcracker phenomenon. Hilar portion of the left renal vein and the gonadal vein are distended. Distended lumbar and azygous collaterals may be seen in some cases.

FIGURE 2.

Computed tomographic venogram showing nutcracker phenomenon. Left renal vein is compressed between the aorta and the superior mesenteric artery (white arrow). Left renal vein (black arrowhead) with distended hilar portion (black arrow).

FIGURE 3.

Computed tomographic venogram (digital reconstruction) showing grossly distended gonadal vein (white arrow) in the same patient as in Figure 2. Compression point marked by black arrow.