|
Nutcracker syndrome (NS), also called left renal vein entrapment
syndrome, is defined by non-glomerular hematuria originating from
the left collecting system caused by compression of the left renal
vein between the aorta and the proximal superior mesenteric artery.
The compression of the left renal vein leads to an elevation of
left renal venous pressure and the formation of ureteral and renal
pelvic venous varicosities and the development of collateral veins.
The etiology of nutcracker syndrome has been suggested to be the
abnormal branching of the superior mesenteric artery from the aorta.
The pathophysiology of nutcracker syndrome is not fully understood.
Presumably, the increased pressure in the left renal vein causes
rupture of the thin-walled varices surrounding the collecting system
in the renal fornix causing bleeding into the left upper urinary
tract. The incidence of nutcracker syndrome is unknown; however,
the frequency of the syndrome seems to be similar in both genders.
The most common clinical signs and symptoms of nutcracker syndrome
include microscopic hematuria with or without proteinuria and macroscopic
hematuria. Some patients also demonstrate symptoms of increased
hematuria with orthostatism. Physical symptoms of nutcracker syndrome,
although rare, can include lower abdominal pain, flank pain, and
symptoms of orthostatic disturbances (e.g. tachycardia, dizziness).
Male patients can develop a left varicocele.
Urine erythrocyte morphological studies combined with recent advances
in imaging techniques, have led to early detection of nutcracker
syndrome among patients with idiopathic persistent hematuria. This
disease has been diagnosed using venographic imaging, which measures
the pressure gradient between the left renal vein and the inferior
vena cava, and using intra-arterial digital subtraction angiography.
Magnetic resonance imaging (MRI) provides a non-invasive method
for diagnosing nutcracker syndrome. MR imaging in the coronal and
sagittal planes allows for exceptional definition of vascular anatomy
and can demonstrate left renal vein entrapment and compression and
the development of the collateral veins.
Treatment of nutcracker syndrome depends on the severity and consequences
of the bleeding. Patients with intermittent and rare episodes of
hematuria and no anemia may only require close follow-up and iron
supplementation as needed. However, surgery must be considered in
the rare cases of nutcracker syndrome where gross hematuria is persistent
or frequently recurs and causes anemia and/or is accompanied by
left flank pain. Surgical procedures that have improved congestion
of the left renal vein include resection of pre-arotic fibrous tissue,
a renocaval venous reimplantation, placement of a synthetic wedge
into the bifurcation of the superior mesenteric artery, autotransplant
convalescence, and an artificial bypass from the left renal vein
to the inferior vena cava. These procedures have resulted in complete
resolution of hematuria within several months post surgery.
References:
- Semelka, Richard. Abdominal-Pelvic MRI. New York: Wiley-Liss
Inc, 2002. pp. 903-904.
- Lidove O, Orozco R, et al. A Young Woman with Intermittent
Macroscopic Haematuria. Nephrology Dialysis Transplantation.
2001; 16: 853-855.
- Takemura T, Iwasa H, et al. Clinical and Radiological Features
in Four Adolescents with Nutcracker. Pediatric Nephrology.
2000; 14: 1002-1005.
- Takashi U, Ko M, et al. A Case of Nutcracker Syndrome Presenting
with Hematuria in Pregnancy. Nephron. 2002; 91: 764-765.
- Hohenfellner M, Steinbach F, et al. The Nutcracker Syndrome:
New Aspects of Pathophysiology, Diagnosis, and Treatment.
The Journal of Urology. 1991; 146: 685-688.
|
;)
;)