Nutcracker syndrome in a child with familial Mediterranean fever (FMF) disease: renal ultrastructural features

Nutcracker syndrome in children: Appearance, diagnostics, and treatment - A systematic review

BACKGROUND

The nutcracker syndrome (NCS) is defined by compression of the left renal vein (LVR) and may present with a wide variety of symptoms. Due to its rarity in pediatric patients, incidence, diagnostics and performed therapy regimen are widely undefined. To this date, there are only case reports and small collectives of pediatric patients described but comprehensive research is lacking.

METHODS

A systematic literature research on pediatric NCS was carried out on Medline and Scopus databases according to PRISMA principles using predefined search terms and inclusion criteria. The PROSPERO registered review (CRD42021237415) identified patients' characteristics regarding age, sex, clinical symptoms, applied diagnostic methods and treatment options.

RESULTS

In total 47 articles were included. Overall, 423 children (218 boys and 205 girls) with diagnosed NCS were included in the analysis. Mean age was 12.0 (boys 12.9, girls 12.0) years. Hematuria was most common presentation (55.5%), followed by proteinuria (49.9%). Classical flank pain was only detected in 19.1% of patients. Sonographic evaluation was the most commonly used diagnostic tool (99%). Invasive diagnostic studies were performed in 97 children. 86.8% patients were treated conservatively and 94.9% showed complete resolution (42.8%) or at least improvement (52.2%) of symptoms. Type of operative treatment comprised of open surgery with transposition of LRV, endovascular stenting and laparoscopy.

CONCLUSIONS

Overall, data quality regarding NCS in children is poor. However, conservative approach in pediatric patients is recommended and should be regarded first treatment option. Diagnostic and treatment should follow a defined algorithm when NCS is suspected. Sufficient observation and follow-up must be assured in all patients to get significant results in this heterogenous syndrome.

LEVEL OF EVIDENCE

V-IV.

Nutcracker syndrome: a potentially underdiagnosed cause of proteinuria in children with familial Mediterranean fever

INTRODUCTION

Familial Mediterranean fever (FMF) is the most common hereditary autoinflammatory disease with an increased risk for secondary amyloidosis. Since lifelong colchicine has been the treatment of choice that prevents renal amyloidosis, non-amyloid kidney diseases are more frequently considered in the differential diagnosis of proteinuria. Nutcracker syndrome (NCS) can be one of the confounding causes. This long-term retrospective study aimed to evaluate the causes of proteinuria in a pediatric cohort of patients with FMF and discuss changing trends in recent years .

METHODS

Demographic, clinic, and laboratory data were extracted from electronic medical records of patients with FMF. All urine tests of the study population were reviewed. Patients were evaluated for persistent proteinuria and grouped according to the etiology of proteinuria.

RESULTS

A total of 576 patients with FMF were identified with a mean follow-up of 6.3 years in the last 10 years; 8% had persistent proteinuria. The etiology was NCS in 67.5% of the patients with proteinuria, and renal amyloidosis was less commonly encountered (15%) without any new diagnosis for the last 8 years. Non-amyloid kidney diseases were also diagnosed in 17.5% of the patients. Patients with NCS had significantly lower BMI than other patients in the cohort and less subclinical inflammation, higher hemoglobin concentration, and milder levels of proteinuria with normal serum albumin and eGFR than other patients with proteinuria.

CONCLUSION

Nutcracker syndrome is the leading cause of proteinuria in children with FMF nowadays, and it should be kept in mind during the evaluation of proteinuria in these patients. A higher resolution version of the Graphical abstract is available as Supplementary information.

Evaluation of Renal Parenchyma Elasticity With Acoustic Radiation Force Impulse Quantification in Nutcracker Syndrome and Comparisons With Grayscale Doppler Sonography and Laboratory Findings

OBJECTIVES

We sought to evaluate renal parenchymal elasticity with Virtual Touch quantification of acoustic radiation force impulse imaging in nutcracker syndrome and to compare shear-wave velocity (SWV) values with grayscale Doppler sonography and laboratory findings.

METHODS

Thirty-eight healthy volunteers and forty-three nutcracker syndrome patients were enrolled in this prospective study. SWV values for both kidneys in nutcracker syndrome patients and healthy volunteers were evaluated. Grayscale Doppler ultrasound and laboratory findings were obtained and compared with SWV values in both nutcracker syndrome patients and healthy volunteers.

RESULTS

In nutcracker syndrome patients, SWV values for the left kidney were significantly lower than those for the right kidney (n = 43; 1.93 ± 0.43 m/s vs 2.53 ± 0.45 m/s [P < .001]). Healthy volunteers' SWV values for both kidneys had no statistically significant differences. There was a statistically significant difference between nutcracker syndrome patients and healthy volunteers for the SWV values and body mass index values. There was no statistically significant correlation between SWV values of nutcracker syndrome patients and age, gender, glomerular filtration rate, body mass index, vein diameter ratio, peak velocity ratio, or resistive indices.

CONCLUSIONS

Acoustic radiation force impulse imaging offers new, additional information on the affected left kidney parenchymal changes in nutcracker syndrome patients.

Clinical course of children with nutcracker syndrome

OBJECTIVE

To evaluate the clinical properties of patients with nutcracker syndrome (NCS).

MATERIALS AND METHODS

The medical records of the patients with NCS were retrospectively investigated, and the patients' sex, age, presenting symptoms, urinalysis findings, associated diseases, and body mass indexes were recorded.

RESULTS

A total of 23 nonconsanguineous patients (11 male and 12 female patients, mean age 141 ± 36 months). Two patients had posterior NCS. Seventeen patients presented with 1 or >1 symptom. Fatigue and lassitude (n = 1), flank pain (n = 8), abdominal pain (n = 7), varicocele (n = 2), and macroscopic hematuria (n = 9) were the presenting symptoms. Only 6 patients had received a diagnosis of NCS from the urinalysis findings, which revealed microscopic hematuria or non-nephrotic proteinuria. The urinalysis findings disclosed isolated proteinuria in 6, hematuria plus proteinuria in 8, and macroscopic hematuria in 9 patients. Orthostatic proteinuria was detected in 7 patients. In patients with regressed hematuria and proteinuria, the body mass index was markedly increased at the end of the follow-up period relative to at diagnosis (at diagnosis 16.9 ± 4.0 kg/m(2); at the end of the follow-up period 18.6 ± 4.6 kg/m(2); P = .028).

CONCLUSION

The diagnosis of NCS should be considered in the presence of symptoms such as proteinuria and hematuria and should be absolutely ruled out before attempting renal biopsy. An apparent correlation between an increased body mass index and regression of symptoms was seen.

Newly-identified symptoms of left renal vein entrapment syndrome mimicking orthostatic disturbance

BACKGROUND

In addition to the urinary abnormalities, symptoms of left renal vein entrapment between the aorta and superior mesenteric artery (left renal vein entrapment syndrome, LRVES) may include abdominal and flank pain as well as chronic fatigue. We investigated various LRVES symptoms in this study.

METHODS

In 53 pediatric LRVES patients treated at our department, 22 had a score of 5 points or higher on orthostasis. Initial evaluation of LRVES by abdominal ultrasonography showed a stenotic-to-prestenotic vein diameter ratio of 0.2 or less. Definitive diagnosis was made by computed tomography and magnetic resonance angiography. Cortisol, catecholamine (CA), and brain natriuretic peptide (BNP) were also measured.

RESULTS

The frequency of LRVES was 2.5 times higher in girls than in boys. Low or very low body mass indexes were seen in both sexes. The most common initial finding was urine abnormalities, followed by dizziness and malaise. In 6 patients, orthostasis precluded school attendance. Ten patients had orthostasis scores above 12. Patients unable to attend school had either low levels of plasma or urinary cortisol. Midodrine significantly decreased orthostasis scores. Some patients required treatment with fludrocortisone. Plasma CA, renin, and BNP levels were all normal.

CONCLUSIONS

Locally excessive venous pressure may cause reversible adrenal dysfunction with transitory Addisonian symptoms. Children with cryptogenic malaise or severe orthostasis should be evaluated for LRVES.

Renal vein obstruction and orthostatic proteinuria: a review

OBJECTIVES

The cause of orthostatic proteinuria is not clear but may often relate to obstruction of the left renal vein in the fork between the aorta and the superior mesenteric artery (=renal nutcracker). However, reports dealing with proteinuria only marginally refer to this possible cause of orthostatic proteinuria. We analysed the corresponding literature.

RESULTS

Five reports addressed the frequency of renal nutcracker in 229 subjects with orthostatic proteinuria. Their age ranged between 5.2 and 17 years (female-to-male ratio: 0.96:1.00). Imaging studies demonstrated renal nutcracker in 156 (68%) subjects. Renal nutcracker was also demonstrated in 9 anecdotal reports for a total of 53 subjects with postural proteinuria. Very recently, 13 Italian subjects with orthostatic proteinuria associated with renal nutcracker were reassessed 6 years after the initial diagnosis: in nine subjects, both orthostatic proteinuria and renal nutcracker had disappeared; in three, both orthostatic proteinuria and renal nutcracker had persisted; and in one, orthostatic proteinuria had persisted unassociated with renal nutcracker.

CONCLUSIONS

These data provide substantial support for renal nutcracker as a common cause of orthostatic proteinuria.