Expanding the Clinical Spectrum of Pediatric Nutcracker Syndrome: A Case of Nonrenal Presentation.

Nutcracker Syndrome—How Well Do We Know It?

PurposeTo estimate the incidences of left renal vein (LRV) entrapment by right renal artery (RRA), a phenomenon primarily reported as case reports.MethodsThe cross-sectional study consecutively screened renal vessel CT data of 38 (Renal) patients with nephropathy and 305 (Non-renal) patients with peripheral arterial diseases in a teaching hospital in northeast China between November 2018 and March 2023. The LRV compression by adjacent anatomical structures, including but not limited to RRA and multiple compression-related parameters, were investigated through multiplanar analysis of the CT data.ResultsThe overall LRV entrapment rates by adjacent structures were 41.93% (12/31) and 24.00% (6/25), the rates of RRA-sourced LRV compression 22.58% (7/31) and 20.00% (5/25), and the rates of compression by superior mesenteric artery (SMA) 16.13% (5/31) and 4.00% (1/25) in the Renal and Non-renal groups, respectively, with no significance. The venous segments distal to the RRA-compressed site had a significantly larger transectional lumen area than those of the non-compressed veins in both groups (3.09 ± 1.29 vs. 1.82 ± 0.23, p < 0.001 and 4.30 ± 2.65 vs. 2.12 ± 0.55, p = 0.006; maximum-to-minimum area ratios in Renal and Non-renal groups, respectively). Nearly 80% of RRAs were found arising anteriorly rightwards instead of passing straight to the right.ConclusionRRA-sourced LRV compression was not rare, and its incidence was higher than that of the compression by SMA in both patient cohorts. RRA could be a more common compression source than SMA concerning LRV entrapment. Further investigations involving different populations, including healthy individuals, are needed.

Chronic abdominal pain and haematuria in internal medicine: do not forget about the Nutcracker syndrome.

Background and Aims Clinically, left renal vein (LRV) entrapment is almost equivalent to the nutcracker phenomenon (NCP). However, there is still much uncertainty and debate about the prevalence of NCP and its diagnostic criteria. As a particular type of LRV entrapment, the LRV compression by the right renal artery (RRA) was primarily reported as case reports. The study was designed to investigate the RRA-sourced LRV compression in two selected patient cohorts. Method The cross-sectional study consecutively selected 38 hospitalized kidney patients diagnosed with membranous nephropathy (Renal group) and 305 peripheral vascular inpatients or outpatients (Non-renal group) in the Second Affiliated Hospital of Harbin Medical University in China from November 2018 to March 2023. The patients with computed tomography (CT) of renal veins or abdominal aorta were included in both groups if axial CT imaging could visualize the renal vessels and was with regular and adequate layer thinness to perform multiplanar reconstruction analysis. Any potential situations that might cause positional or course changes in proximal RRA or LRV due to pathological reasons were excluded from the study. The CT data of LRV compression by different anatomical sources, including but not limited to RRA, was analyzed. Results With other anatomical compression sources excluded, there were 22.58% (7/31) and 20.00% (5/25) LRVs compressed by the RRAs in the Renal and Non-renal groups, respectively, with no significant difference (p = 1.0). The distal segments of the LRVs compressed by RRAs have a significantly larger lumen area than those of non-compressed veins (p &amp;lt; 0.01 in both groups). The overall incidence of NCP was calculated as 10.71% (6/56). Complex compressions, namely those LRV compressions by another adjacent structure besides RRA, coincided in 7.14% of the total cases (4/56). Conclusion Our study showed that it was not rare for the proximal RRA to compress the end of LRV. The detected incidence of RRA-sourced LRV compression was twice that of the entrapment related to the superior mesenteric artery, the mainstay of NCP. Though this finding came from two relatively small subject populations, it challenged the present connotation of LRV entrapment. Further repetitive studies are needed to test if such a phenomenon prevails in different populations, including healthy individuals. Legends for all figures: Green thick arrows, RRA; green arrowheads, superior mesenteric artery (SMA); red-edged white arrows, left renal artery (LRA); white short-shafted arrows, LRV; white long-shafted arrows, inferior vena cava (IVC); transparent or white arrowheads, compressed sites.

Objectives: Nutcracker phenomenon is caused by the compression of left renal vein between the superior mesenteric artery and the aorta. There are also variants namely the ‘posterior nutcracker phenomenon’ where the posteriorly located retroaortic or circumaortic left renal vein is compressed between the aorta and the vertebral body. The aim of this study is to define vascular alterations in veins other than the left renal vein secondary to anterior and posterior nutcracker phenomena and emphasize their contribution to diagnosis. Methods: Computed tomography images of 57 patients with nutcracker phenomenon were retrospectively nvestigated fort he presence of secondary vascular alterations. In addition, 169 patients with a retroaortic and 32 patienys with a circumaortic left renal vein variation were searched for thepresence of a posterior nutcracker phenomenon and associated secondary vascular findings. Results: Dilatation of left gonadal (n: 15, 26%), left lumbar or ascending lumbar (n: 9, 16%), hemiazygos (n: 4, 7%), left suprarenal (n: 4, 7%), and inferior phrenic (n:2, 4%) veins were seenin anterior nutcracker phenomenon. Pelvic varices/varicoceles pseudothrombosis in the left renal vein were present in 7(12%) and 4 ( 7%) patients, respectively.. There was a appearance in 4 patients. 14 % of 169 patients with a retroaortic left renal vein and 16 % of 32 patients with circumaortic left renal vein showed a posterior NC phenomenon and associated vascular alterations. Conclusions: Awareness of the secondary vascular findings in nutcracker phenomenon may aid in the diagnosis and guide management.

Nutcracker syndrome, also called left renal vein entrapment syndrome, is a cause of non-glomerular hematuria with difficulties in diagnosis. Multidetector computed tomography (MDCT) is a powerful tool to prevent unnecessary diagnostic procedures. To retrospectively determine the prevalence of nutcracker phenomenon and nutcracker syndrome seen in MDCT in consecutive patients. The institutional review board approved the study and waived the requirement for informed consent. Abdominal contrast-enhanced MDCT scans were reviewed from 1000 consecutive patients. MDCT scan assessment included renal vein diameter measurements and evaluation for the presence of anterior or posterior left renal vein entrapment. Electronic medical records and urine analysis reports of patients with left renal vein entrapment were reviewed. Student's t test was used to assess differences in renal vein diameter in patients with left renal vein entrapment. Left renal vein entrapment was observed in 10.9% (109), retro-aortic left renal vein in 6.5% (65), entrapment of left renal vein between superior mesenteric artery and aorta in 4.1% (41), and circumaortic left renal vein in 0.3% (3) of patients. Mean diameters of right (8.8 ± 1.9 mm) and unentrapped left (8.9 ± 1.8 mm) renal veins were not significantly different (P = 0.1). The mean diameter of anterior entrapped left renal veins (10.3 ± 2 mm) was significantly greater (P = 0.04) than contralateral renal veins (8.6 ± 2.1 mm) in their widest portion. In 8.8% of patients with the left renal vein entrapment, urine analysis showed isomorphic hematuria or proteinuria with no other known cause. Varicocele and pelvic congestion were seen in 5.5% of patients with the left renal vein entrapment. Left renal vein entrapment is not a rare entity and renal nutcracker phenomenon might be underdiagnosed.

Left Renal Vein Compression: A Cause for Right-Sided Flank and Leg Pain

Left renal vein compression between the aorta and the superior mesenteric artery at an acute angle of the origin of the latter (“the nutcracker syndrome”) often leads to phlebohypertension in the left renal vein causing a combination of structural and functional changes in the kidneys and pelvic organs, different clinical manifestations such as left-sided varicocele, hematuria, pelvic venous congestion syndrome, the development of renal failure. The objective of the research: to determine indications for surgical and conservative treatment of aorta mesenteric compression. Materials and methods. The study included 210 patients (142 men and 68 women) with suspected “nutcracker syndrome” who were referred to vascular surgeons for a consultation by urologists and gynecologists during the period from 1999 to 2020, mainly from the western regions of Ukraine (about 11 million population). The age of the patients ranged from 12 to 52. All patients were interviewed for specific complaints: pain in the left lumbar region and left half of abdomen, inability to eat large amounts of food, hematuria, proteinuria, hemospermia, erectile dysfunction, left sided varicocele in men, and left sided pudendal varicosity and dysmenorrhea in women. All referred patients with suspected “nutcracker syndrome” underwent color Doppler ultrasound to determine the presence of pathological reflux in the left renal and gonadal veins by measuring peak systolic velocities in order to confirm or exclude that pathology. The patients with confirmed left renal vein stenosis underwent CT angiography. Results. According to color Doppler ultrasound, different degree of aorta mesenteric compression was confirmed in 138 (65.7%) patients (83 men and 55 women), critical left renal vein stenosis was observed in 35 of them. Two patients were diagnosed with the retroaortic left renal vein (“posterior nutcracker”). According to observations, clinical manifestations of AMC syndrome severe forms occurred in case of an increase in the diameter of the distal part of the LRV compared to its proximal segment by 3-6 times as well as in case of an increase in peak systolic velocity in the stenosed proximal segment by 6-14 times (by 8.7 times on average) compared to the left renal vein distal segment. Conclusions. Color Doppler ultrasound with determination of peak systolic velocities and diameters of the left renal and gonadal veins, pathological reflux in them must be the obligatory diagnostic stage in the patients with suspected AMC. The choice of treatment approach should be made taking into account clinical and laboratory indices, as well as the assessment of AMC severity according to instrumental data (ultrasound, CT angiography, MRA, etc.). The severity of pathomorphological changes in the pelvic organs and their consequences proves the need to eliminate phlebohypertension in the left renal and gonadal veins. LRV transposition proves its effectiveness in the remote postoperative period.

Sirs, Compression of the left renal vein (LRV) between the aorta and the superior mesenteric artery (SMA), known as the nutcracker phenomenon (NCP), can cause gross or microscopic hematuria, flank pain, proteinuria, or a combination of these clinical features [1, 2, 3]. The phenomenon causes hypertension of the LRV, consequently causing LRV compression, left gonadal vein varices, and unilateral hematuria [2, 4]. A recent report documented orthostatic proteinuria associated with the NCP [1, 5, 6, 7]. We describe two siblings with microscopic hematuria caused by NCP. These patients were a 3-year-old brother and a 5-year-old sister born to healthy non-consanguineous parents. Their family history manifested no renal diseases. Microscopic hematuria was first indicated in both patients by an annual screening urinalysis at their kindergarten. Their respective blood chemistries and urinary calcium/creatinine ratios were normal. Urine was normal except for sediment containing 5–20 red cells per high-power field. Repeated urine cultures showed no pathological organisms. Urinary red cell morphology revealed predominantly (>90%) isomorphic cells. Serum complement, IgA, IgG, and IgM concentrations, as well as antistreptolysin O titer, antinuclear antibody, antidouble-stranded DNA antibody, and rheumatoid factor were in the normal range. Ultrasonography of the kidneys showed marked dilatation of the LRV in the hilar portion and severe compression of the LRV between the aorta and the SMA, which was an indirect finding that is typical of NCP. Entrapment of the LRV is not easily detectable using conventional means. Selective renal venography, with the measurement of the gradient pressure between the LRV and the inferior vena cava, or intra-arterial digital subtraction angiography has been used for the diagnosis of NCP [8]. Doppler ultrasonography, three-dimensional helical computed tomography, and magnetic resonance angiography have been employed recently as useful noninvasive diagnostic tools [1, 3, 4, 5]. Abnormal branching of the SMA from the aorta is suggestive of the fundamental pathophysiology of NCP [1]. Nevertheless, it remains unclear why so few patients have experienced compression of the LRV and why LRV hypertension causes hematuria. Additional studies have demonstrated a new variant of NCP with different anatomical details [9]. The urinary red cell morphology is not sufficiently reliable to distinguish a glomerular source of bleeding from a non-glomerular source [2]. Clarification of non-glomerular hematuria in patients with NCP, who also have other co-existing renal disorders causing hematuria, is more complicated. Concomitant IgA nephropathy or membranous nephropathy associated with the NCP has been reported [2]. NCP is not a hereditary disease: occurrence of NCP within the same family or in close relatives is rare. NCP may have occurred coincidentally, causing hematuria in both siblings. Alternatively, they may have had underlying familial benign hematuria in association with NCP despite a negative family history. Further evaluation is necessary to elucidate the etiology of non-glomerular hematuria of these siblings.

Background: Nutcracker syndrome (NCS) is a rare and often underdiagnosed vascular compression disorder, primarily involving the entrapment of the left renal vein (LRV) between the superior mesenteric artery and the abdominal aorta. This study presents a retrospective study of nine patients diagnosed with NCS who underwent surgical intervention, aiming to explore diagnostic challenges and surgical management outcomes. Methods: We conducted a retrospective analysis of nine patients diagnosed with NCS and treated surgically at our institution from 2021 to 2024. Data collected included patient demographics, clinical presentations, diagnostic findings, surgical procedures, and postoperative outcomes. Results: The cohort consisted of six females (aged 24–30 years) and three males (aged 14–22 years) diagnosed with NCS and treated surgically at our institution between 2021 and 2024. The main presenting symptoms included chronic abdominal pain, hematuria, and urogenital symptoms. The diagnosis was confirmed using ultrasonography and computed tomography angiography, which revealed narrowed aorta-mesenteric angles (18°–45°) and LRV compression. All patients underwent LRV reimplantation through a midline transperitoneal approach. Postoperative recovery was uneventful, with normal venous flow observed on Doppler studies between postoperative days 3 and 4. Patients experienced significant symptom improvement and were discharged within 4–6 days postsurgery. Conclusion: This case series demonstrates that LRV reimplantation is an effective surgical approach for managing NCS. Early diagnosis with appropriate imaging and timely surgical intervention can lead to favorable outcomes in a diverse patient population. Further research is warranted to assess the long-term efficacy of this surgical technique.

We found that patients with orthostatic protein-uria had entrapment of the left renal vein (LRV) by the aorta and superior mesenteric artery (SMA). Of 15 patients studied, ultrasonographic examination showed 13 cases of typical LRV entrapment with prestenotic dilatation, and 2 cases of mild LRV compression between the aorta and SMA. Intra-arterial digital subtraction angiography and monitoring of pull-back pressure from LRV to the inferior vena cava (IVC) were performed on 2 patients with 4+ proteinuria. Accumulation of contrast medium was seen with mild back-flow to the collateral veins, and pressure gradients between LRV and IVC were 4 mmHg and 8 mmHg, respectively. Eighty school-children formed a control group and were investigated ultrasonically. Nine showed typical LRV entrapment, among whom 3 had moderate to massive orthostatic proteinuria. The discovery of LRV entrapment in patients with orthostatic proteinuria gives definite evidence of LRV congestion and may be possibly a cause of massive protein secretion from the left kidney.

Objectives The aims of the study were to identify whether left renal vein (LRV) entrapment was more prevalent in IgA nephropathy (IgAN) and Henoch–Schönlein purpura nephritis (HSPN) compared with other types of renal diseases, and the association of LRV entrapment with glomerular incidental IgA and galactose-deficient-IgA1 (Gd-IgA1) deposition. Methods A total of 797 patients with biopsy-proven kidney diseases have been screened for LRV entrapment by color Doppler ultrasound, and the prevalence of LRV entrapment in different types of renal diseases were then analyzed. Propensity score matching analysis was used to adjust for age, gender, and body mass index. Immunostaining of Gd-IgA1 with KM55 was performed in paraffin-embedded sections of renal biopsy specimens. Results LRV entrapment was diagnosed in 47 patients (6%) with several kinds of renal diseases in our cohort. A total of 32 (68%) LRV entrapments were combined with expanded IgAN (idiopathic IgAN and HSPN). The prevalence of LRV entrapment in expanded IgAN was significantly higher than that in non-expanded IgAN (17 vs. 2%, p < 0.001), even after adjustment for age, gender, and body mass index by propensity score matching analysis (13 vs. 2%, p < 0.001). Removing expanded IgAN and LN, glomerular incidental IgA deposition was observed to be significantly more common in patients with LRV entrapment compared with patients without it (43 vs. 9%, p < 0.001). Furthermore, in glomerular diseases with incidental IgA deposits, significantly much larger proportion of patients with LRV entrapment were positive for glomerular Gd-IgA1 in contrast to patients without LRV entrapment (5/5 vs. 5/17, p = 0.01). Conclusions LRV entrapment coexisted with several kinds of renal diseases, with a significantly higher prevalence in patients with idiopathic IgAN and HSPN. In patients of LN and IgAN-unrelated disease with LRV entrapment, glomerular IgA and Gd-IgA1 deposition was more common compared with patients without LRV entrapment.

The use of multidetector computed tomography (MDCT) in routine abdominal explorations has increased the detection of the nutcracker phenomenon, defined as left renal vein (LRV) compression by adjacent anatomic structures. The embryology and anatomy of the nutcracker phenomenon are relevant as a background for the nutcracker syndrome, a rare cause of hematuria as well as other symptoms. MDCT examples of collateral renal vein circulation (gonadal, ureteric, azygous, lumbar, capsular) and aortomesenteric (anterior) and retroaortic (posterior) nutcracker phenomena in patients with no urologic complaint are shown as well as studies performed on patients with gross hematuria of uncertain origin. Incidental observation of collateral veins draining the LRV in abdominal MDCT explorations of asymptomatic patients may be a sign of a compensating nutcracker phenomenon. Imbalance between LRV compression and development of collateral circulation may lead to symptomatic nutcracker syndrome.

Background: One of the causes of gross hematuria is nutcracker syndrome or renal vein entrapment. The computerized tomography (CT) scan can demonstrate the precise left renal vein (LRV) compression between the aorta and the superior mesenteric artery. These modalities are usually applied for initial investigations. At present, there is no definite cutoff point to diagnose nutcracker syndrome in patients who present with asymptomatic microscopic hematuria (AMH). Objective: To study whether the nutcracker syndrome might be associated with AMH and to determine the definite cutoff point to diagnose nutcracker syndrome. Materials and Methods: The authors retrospectively reviewed the CT scans of patients diagnosed with AMH and had no abnormal urological findings from standard investigations compared with patients in a control group who had normal urine exams and no urological abnormalities from CT scans. CT scan assessment included the diameter ratio of the LRV at the aortomesenteric angle and the renal hilar, the aortomesenteric distance, and the aortomesenteric angle. Results: Forty-eight patients diagnosed with AMH were included in the present study. The diameter ratio of the LRV at the aortomesenteric angle and the renal hilar in the AMH group was 0.7 compared to 0.9 for the control group (p=0.001). The mean aortomesenteric angle in patients with AMH was 45.9 degrees compared to 54.8 degrees in the control group (p=0.004). The mean aortomesenteric distance in patients with AMH was 1.36 cm compared to 1.56 cm in the control group (p=0.032). Conclusion: These data showed the significant difference in the diameter ratio of the LRV at the aortomesenteric angle and the renal hilar, the aortomesenteric angle, and the aortomesenteric distance between patients with AMH and the normal population. Therefore, the nutcracker syndrome may be associated with AMH. Keywords: Microscopic hematuria, Nutcracker, Left renal vein

Nutcracker phenomenon or renal vein entrapment is classically seen as a compression of renal vein in between abdominal aorta and superior mesenteric artery with patients being asymptomatic or clinically manifested in the form of nutcracker syndrome as proteinuria, hematuria, flank pain, pelvic congestion in women, and varicocele in men. In this report, we are presenting a case of rare variant of nutcracker phenomenon along with brief review of anatomy, pathophysiology, public health, and clinical significance of nutcracker syndrome. On a routine dissection of an adult male cadaver, we noticed an unusual arrangement of the structures at the hilum of the left kidney showing entrapment of renal vein between left anterior inferior and posterior segmental renal arteries. The variation in the course of left anterior inferior segmental renal artery leads to compression of left renal vein at renal hilum. Therefore, we have named this rare abnormal anatomical entity as hilar nutcracker phenomenon. The structures in the right renal hilum are normal. The objective of this paper is to report an unusual but important variant of nutcracker phenomenon and also give collective knowledge of such anatomical variations in renal vasculature that will help in diagnosing and treating such rare renal disorder.