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

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.

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.

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.

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.

V-IV.