Nutcracker syndrome

What is Nutcracker syndrome?

Nutcracker syndrome is a rare disease caused by compression of the left renal vein between the abdominal aorta and the superior mesenteric artery. This causes an increase in pressure between the left renal vein (LRV) and the inferior vena cava of up to 3 mm Hg, when the normal value should be below 1 mm Hg. This, in turn, causes the septa between the veins to rupture, producing unilateral left renal hematuria, i.e., internal fistulas and renal bleeding.

Most cases with symptoms occur between the third and fourth decade of life, affecting more women than men, with most cases reported in the Far East.

There are three types of Nutcracker syndrome:

  • Nutcracker or anterior Nutcracker syndrome. This is the most common form, when compression of the left renal vein occurs on the side of the aorta and mesenteric artery.
  • Posterior nutcracker syndrome. In this case the renal vein is trapped and compressed between the spinal column and one of the two arteries.
  • Combined Nutcracker syndrome. This is a rare case, where the left renal vein is pinched in its anterior branch by the two arteries, while the posterior branch is pinched between the spine and the aorta.

Prognosis of the disease

It is a disease that is usually benign and has no major complications, and the prognosis is usually good. However, sometimes there may appear some complications at renal level that can be very disabling and even lead to the patient’s life. One situation that could occur is that, if there is recurrent and regular bleeding, the patient could suffer from anemia, nephropathy and even altered blood pressure and arterial pressure.

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Symptoms of Nutcracker syndrome

The symptoms of Nutcracker syndrome are either gynecological or urological. Urological symptoms include:

  • Unilateral macroscopic or microscopic hematuria, i.e., visible in the urine or under the microscope.
  • Varicose veins in the legs
  • Abdominal pain on the left side
  • Varicocele

Gynecological symptoms (often referred to as “pelvic congestion syndrome”) include:

  • Dysmenorrhea or dysregulation of the menstrual cycle
  • Postcoital pain
  • Dyspareunia
  • Lower abdominal pain
  • Dysuria
  • Pelvic, buttock, vulvar or thigh varicose veins
  • Emotional disturbances

Medical tests for Nutcracker syndrome

The diagnosis must be very meticulous and the specialist must take a detailed clinical history of the patient. In addition, there are complementary tests that can be of great help, such as a Doppler ultrasound, a computed tomography (CT) scan of the abdomen with contrast, cystoscopy, intravenous urography, cystouretero-renoscopy, manometry of the LRV, angioresonance angiography and phlebography.

What are the causes of Nutcracker syndrome?

Symptoms appear when the pressure level in the renal vein increases, damaging the septa between veins and the renal apparatus, with blood entering the urine. At the same time this would cause venous circulation to other places, such as the gonadal and urethra.

The causes are not clear but it could be caused by alterations at the embryonic level. Although it is more common in people from the Far East, there is no proven link to genetic inheritance, so most cases are “sporadic”.

In children, it can sometimes occur as a result of growth-related changes in the body. In adults, there are several hypotheses:

  • Abnormalities such as duplications of the renal vein.
  • Presence of tumors or inflammations that push the arteries, so that they compress the left renal vein.
  • A too low body mass (the fat in this area makes more space between both arteries).
  • Hyperlordosis or a problem in reference to the position of the kidneys in response to changes in posture.
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Can it be prevented?

Nutcracker syndrome cannot be prevented but, as noted above, it is usually a benign condition.

Treatments for Nutcracker’s syndrome

Nutcracker syndrome is usually a benign disease, with the exception of a few cases, where it is life threatening. In most cases observation and monitoring of the patient’s condition will be sufficient. In other cases some intervention will be necessary, usually surgical. Among the most common operations is the implantation of an intravascular or extravascular stent, which is a device that allows the affected vessel to be kept open. If there is a very large renal bleeding, blood transfusions may be necessary. In other extreme cases, a kidney transplant or a renal vein bypass may be required.

What specialist treats it?

The specialist who treats Nutcracker syndrome is, as a rule, the vascular surgeon, but nephrologists, urologists and gynecologists may also diagnose this pathology.