What Each Clinical Anatomist Has to Know about Left Renal Vein Entrapment Syndrome (Nutcracker Syndrome): A Review of the Most Important Findings

Nutcracker syndrome (a Delphi consensus)

BACKGROUND

Nutcracker syndrome (NCS) describes the symptomatic compression of the left renal vein between the aorta and superior mesenteric artery. Whereas asymptomatic compression is a common radiological finding, patients with NCS can report a range of symptoms. There are no specific diagnostic criteria and interventions include a range of open surgical and endovascular procedures. Therefore, we wished to develop an international consensus document covering aspects of diagnosis, management, and follow-up for patients with NCS.

METHODS

A three-stage modified Delphi consensus was performed. A steering committee developed 37 statements covering 3 categories for patients with NCS: diagnosis, management, and follow-up. These statements were reported individually by 20 international experts in the management of venous disease, using a 5-point Likert scale. Consensus was defined if ≥70% of respondents rated the statement between 1 and 2 (agreement) and between 4 and 5 (disagreement). Those statements without consensus were recirculated in a second round of voting. A third round of the questionnaire was performed with 14 additional statements to clarify diagnostic values of NCS.

RESULTS

Responses were returned by 20 of 20 experts (100%) in round one and 17 of 20 (85%) in round two. Initial consensus was reached in 24 of 37 statements (65%) spread over all categories. Round two achieved a further consensus on 5 out of 10 statements (50%). No categories reported consensus on all statements. In round two consensus was reached in the category of follow-up (4/5 statements [80%]). The final round reached consensus on 5 out of 14 statements (36%). Experts agreed that imaging is obligated to confirm NCS. Experts did not agree on specific diagnostic cut-off values. There was a consensus that the first choice of operative treatment is left renal vein transposition and that the risk of stent migration outweighs the advantages of a percutaneous procedure.

CONCLUSIONS

Consensus was achieved on most statements concerning the assessment and management of NCS. This Delphi consensus identified those areas in which further research is needed, such as antiplatelet therapy, endovascular treatment, and renal autotransplantation. A rare disease registry to improve data and reports of patient outcomes is warranted.

Nutcracker syndrome: challenges in diagnosis and surgical treatment

BACKGROUND

Nutcracker syndrome (NCS) is an uncommon syndrome that presents with signs and symptoms caused by compression of the left renal vein (LRV), whereas 'nutcracker phenomenon' is solely used to refer to the anatomical configuration without clinical symptoms. Treatment for NCS may include non-operative management, open surgical intervention and in some instances endovascular stenting. We present a single-center retrospective case series of patients who presented with NCS managed with open surgical interventions.

METHODS

Single-center, retrospective review of patients managed from 2010-2021. We diagnosed NCS via a thorough clinical examination and additional cross-sectional imaging studies including magnetic resonance venography (MRV) and/or computed tomography venography (CTV). For further confirmation of the diagnosis, duplex ultrasound was frequently combined with contrast venography.

RESULTS

Thirty-eight patients were included in our study from 2010-2021 . Twenty-one (55.3%) patients presented with symptoms including flank pain, abdominal pain, hematuria and fatigue. The remaining 17 (44.7%) patients had nutcracker phenomenon. Within the group of patients diagnosed with NCS, 11 patients underwent LRV transposition. Symptoms related to NCS improved in 10 patients. Hematuria in one patient did not improve.

CONCLUSION

Transposition of the LRV is an effective treatment for NCS. Non-operative management is an option for those patients experiencing less severe or nonspecific clinical symptoms.

Scrotal Pain after Varicocelectomy: A Narrative Review

Varicocele is a frequently encountered urological disorder, which has a prevalence rate of 8 to 15% among healthy men. However, the incidence is higher in male patients with primary or secondary infertility, with up to 35 to 80% of varicocele cases occurring in this population. The clinical manifestations of varicocele typically include the presence of an asymptomatic mass that feels like a “bag of worms”, chronic scrotal pain, and infertility. Most patients with varicocele only undergo varicocelectomy after conservative treatments have failed. Unfortunately, some patients may still experience persistent scrotal pain due to a recurrence of varicocele, the development of hydrocele, neuralgia, referred pain, ureteral lesions, or nutcracker syndrome. Therefore, clinicians should consider these conditions as potential causes of postoperative scrotal pain, and take measures to address them. Several factors can assist in predicting surgical outcomes for patients with varicocele. Clinicians should consider these factors when deciding whether to perform surgery and what type of surgical intervention to use. By doing so, they can increase the likelihood of a successful surgical outcome and minimize the risk of complications such as postoperative scrotal pain.

Ovarian Morphometric and Histologic Characteristics and Correlation with Clinical Factors: A Cross-Sectional Study

Reproductive lifespan is determined by the reserve of ovarian follicles; their quality and quality determine the fertility potential at a given point in time for a particular individual. Inter-individual variations related to morphometry, laterality, medical history, demographic characteristics and ethnicity may impact ovarian histology, which however, has not been extensively studied or documented. The present cross-sectional study aims to investigate the potential association of clinical factors (age, medical and obstetric history) with ovarian morphometry and histology in females of reproductive age in the local population. The sample included 31 specimens of whole human ovaries, obtained from surgical/autopsy procedures in reproductive-aged women, processed at the Pathology Department. Morphometric characteristics were assessed, including shape, color, length, width, thickness and gross ovarian pathology. Random samples of specific dimensions were histologically examined to determine follicular counts. The results were analyzed statistically in correlation to morphometric characteristics and medical history. The majority of the patients had oval-shaped ovaries (77.8% right; 92.3% left; p = 0.368) of whitish color (38.9% right; 46.2% left; p > 0.999). Right ovaries had significantly greater length, width and volume (p-values 0.018, 0.040 and 0.050, respectively). Thickness was equivalent, as well as follicular distribution of all classes. Age correlated inversely with ovarian volume and primordial/primary follicular count on histology. Women with a caesarian-section history yielded significantly lower primordial/primary follicular counts. As estimated by ovarian histology, macroscopic and clinical factors may be significantly associated with actual ovarian reserve.

Fortuitous Discovery of Nutcracker Syndrome During Acute Appendicitis: A Case Report

Nutcracker syndrome (NCS) belongs to a group of rare vascular disorders. It refers to compression of the left renal vein (LRV) generally between the abdominal aorta (AA) and the superior mesenteric artery (SMA). It is one of the most unknown causes of chronic abdominal pain. Herein, we present the case of a young patient who came to the emergency department for acute abdominal pain. Patient's history revealed an uncharacterized chronic epigastric pain evolving for 13 years. The imaging showed acute appendicitis and NCS; the latter finding was the principal explanation for the patient's chronic pain. We hope that the concise and synthetized structure of this case report will help physicians acquire the necessary reflexes to notice and diagnose this already underdiagnosed syndrome.

Left renal vein entrapment in postural proteinuria: the diagnostic utility of the aortomesenteric angle

Nutcracker syndrome related to the left kidney vein compression is a cause of orthostatic proteinuria during childhood. Some studies have shown that the ratios between maximum velocities and anterior-posterior diameters of hilar and aortomesenteric segments of the left kidney vein between upright and supine positions must be more than 4 in order to make a Nutcracker syndrome diagnosis. Our aim was to investigate whether the use of a decrease in aortomesenteric angle between upright and supine positions in the presence of isolated orthostatic proteinuria can be a criterion for the diagnosis of Nutcracker syndrome. Relevant patient information, which included demographic data, clinical examination findings, laboratory data, urinary system ultrasound, and kidney color flow Doppler ultrasound results, were prospectively collected. Thirty-nine pediatric patients with orthostatic proteinuria were included in the study. Left kidney vein compression findings were demonstrated in 31 patients. The ratio of maximum velocities of hilar and aortomesenteric segments of the left kidney vein between upright and supine positions was above 4 in only 7 of our patients. Ratio of aortomesenteric angle between upright and supine positions was significantly decreased for patients with left kidney vein compression findings.  Conclusion: The use of a decrease in the ratio of aortomesenteric angle between upright and supine positions in the presence of orthostatic proteinuria, instead of the ratios for maximum velocities and anterior-posterior diameters of hilar and aortomesenteric segments, can be more helpful for the diagnosis of Nutcracker syndrome in the differential diagnosis of orthostatic proteinuria. What is Known: • Proteinuria may be a sign of an impending kidney disease • Nutcracker syndrome is a cause of orthostatic proteinuria. What is New: • Ratio of aortomesenteric angle between upright and supine positions > 0.6 can be used for Nutcracker syndrome diagnosis.

[Nutcracker syndrome: a rare cause of abdominal pain in adults that shouldn't be ignored: a case report]

De nos jours, la connaissance des anomalies vasculaires est primordiale pour tous les spécialistes en pratique clinique et peut prévenir de graves complications suite à des interventions précoces. Le syndrome de Casse-Noisette ou Nutcraker syndrome résulte d´une compression de la veine rénale gauche (VRG), généralement dans la fourchette formée par l´aorte abdominale et l'artère mésentérique supérieure (AMS), conduisant à la sténose de la partie aorto-mésentérique de la veine rénale gauche et dilatation de sa partie distale. La symptomatologie reste dominée par des douleurs lombaires, abdominales, pelviennes et hématurie. Son diagnostic est basé essentiellement sur les moyens d´imagerie moderne (tomodensitométrie, échographie-Doppler, phlébographie) et son traitement est controversé. Nous rapportons le cas d´une femme âgée de 43 ans, admise dans le cadre d´un bilan radiologique devant des douleurs épigastriques avec pesanteur pelvienne suite à un syndrome de Casse-Noisette.

Superior mesenteric artery syndrome: A review of the literature

Decreased intraabdominal fat can lead to intraabdominal compressive syndromes, such as superior mesenteric artery (SMA) syndrome. This phenomenon is rare but should be considered in a patient with recent rapid weight loss and acute gastrointestinal complaints. A delay in diagnosis and treatment can lead to severe complications, such as a gastric rupture. We report a case of SMA syndrome in a teenage male with recent intentional weight loss and intractable emesis, and the possible associations of SMA syndrome and Nutcracker syndrome.

Splenic vein enlargement, a rare cause of nutcracker syndrome

Abnormal enlargement of the splenic vein is one of the etiologies of nutcracker syndrome that should be considered when examining the causes of this syndrome. Because knowing rare etiologies can help correct diagnose and reduce mortality.

Haematuria without diagnosis? Think about the rare causes…

We describe a case of a 17-year-old man admitted in the emergency room with a 2-month history of intermittent macroscopic haematuria and left lumbar pain. Physical examination and vital signs were normal. Investigation indicated a recurrent non-glomerular haematuria. The Doppler ultrasound revealed a compression of the left renal vein with upstream dilatation which was subsequently confirmed by CT angiography. These findings are in keeping with a case of nutcracker syndrome (NutS). Although asymptomatic in most cases, it can be a rare cause of haematuria. The teenager was referred to paediatric nephrology and was treated conservatively with spontaneous resolution of macroscopic haematuria. With this case, we would like to highlight that in children or adolescents with haematuria without an apparent cause, a high level of suspicion and appropriate imaging are necessary for the diagnosis of NutS.

Nutcracker syndrome accompanied by hypertension: a case report and literature review

Nutcracker syndrome (NCS) refers to characteristic clinical symptoms that develop secondary to the nutcracker phenomenon (NCP), defined as compression of the left renal vein between the superior mesenteric artery and the aorta. A 22-year-old Chinese man presented with a 2-year history of hypertension and left flank pain after activity; his blood pressure fluctuated within 130–150/90–100 mmHg without treatment. He had microscopic hematuria (2+) and increased plasma renin activity. The findings of both color Doppler ultrasound and computed tomography angiography were consistent with a diagnosis of NCS. The patient had no history of familial hypertension or special medications. Secondary hypertension-related examinations showed no significant abnormalities. After placement of an endovascular stent in the left renal vein, normal blood flow resumed and the collateral circulation was reduced. Both the hypertension and flank pain were alleviated within 3 days after the intervention and did not reappear during the following 11 months. NCP/NCS accompanied by hypertension is very rare. The possibility of NCP/NCS should be considered when secondary hypertension cannot be explained by other factors. The mechanism by which hypertension is caused by NCP/NCS is rather complex and deserves further investigation.

Unusual coexistence of double inferior vena cava with nutcracker syndrome-a case report and review of the literature

Knowledge of vessel anomalies is significant for all specialists in clinical practice and may prevent serious complications following medical interventions. Here, the rare coexistence of a duplicated inferior vena cava (IVC) and nutcracker syndrome in a 42-year-old female patient with atypical abdominal pain is presented, using two complementary radiological techniques (colour Doppler ultrasonography and computed tomography angiography). The right renal vein was found to be compressed when passing between the superior mesenteric artery and the abdominal aorta. The lumen dimensions (width × height) of the right IVC and left IVC at the level of termination were 15.8 × 17.7 mm and 13.4 × 12.4 mm, respectively. Ultrasonography revealed low blood flow in the left IVC that was reversed, and thus blood travelled in the same caudal direction as in the aorta. In the right IVC, however, flow travelled in the cranial direction. The simultaneous existence of a duplicated IVC and nutcracker syndrome is an extremely rare vessel anomaly; nevertheless, this dual presence may result in clinical symptoms and would have an impact on medical operations and even minor medical procedures.

Combined Nutcracker and Ehlers-Danlos Syndromes: A Case Report

Introduction

Nutcracker syndrome refers to the clinical manifestations of left renal vein compression between the superior mesenteric artery and the abdominal aorta, causing urinary changes and low back pain.

Report

A 44 year old woman presented with low back and pelvic pain. Following the diagnosis of nutcracker syndrome, she underwent endovascular treatment with renal vein stent placement; however, the patient continued to complain of pain. Further examinations revealed left renal vein compression by the portal vein. The patient underwent a second procedure; however, improvement was temporary and her pain returned. Further investigation revealed previously undetected nephroptosis and hyperelasticity. A diagnosis of Ehlers-Danlos syndrome made, possibly explaining the mobility of viscera and unusual compression of the left renal vein by the portal vein.

Conclusion

Ehlers-Danlos syndrome can cause nutcracker syndrome and may give rise to visceral pain of mixed origin.

Gonadal vein transposition is a safe and effective treatment of nutcracker syndrome

BACKGROUND

Nutcracker syndrome (NCS) is a pelvic venous disorder that results from outflow obstruction of the left renal vein, most often due to a decreased aortomesenteric angle, leading to gonadal vein reflux, pain, and varices. Although a number of open and minimally invasive procedures to treat NCS have been described, the optimal management of this condition remains uncertain. To the best of our knowledge, we have presented the largest case series to date using gonadal vein transposition (GVT) to treat NCS.

METHODS

Patients considered for intervention to treat NCS underwent a rigorous and standardized workup, including axial imaging studies, catheter-based diagnostic procedures, and urinalysis. GVT has been the institutional first-line treatment of NCS for appropriate patients. With institutional review board approval, a retrospective review of patients who had undergone GVT for NCS was conducted.

RESULTS

From 2014 to 2019, 18 GVTs had been performed. Of the 18 patients, none had died or required reintervention, although 2 had required readmission. During a median follow-up of 178 days, complete symptom relief was achieved in 11 patients (61.1%), with 4 patients (22.2%) reporting partial symptom relief and 2 (11.1%) reporting transient symptom relief.

CONCLUSIONS

GVT is a safe and effective procedure to treat NCS in appropriately selected patients with outcomes that compare favorably with those of other described procedures. Appropriate patient selection for this procedure is critical and requires a rigorous and standardized approach to diagnosis and management.

Effect of visceral fat tissue on superior mesenteric artery configuration: Is it superior to BMI?

BACKGROUND/AIMS

To determine the effect of visceral fat volume measured via computed tomography (CT) images of umbilical slices on superior mesenteric artery (SMA) configuration, as compared with body mass index (BMI). In addition, this study aims to determine the effect of lumbar lordosis angle (LLA) on SMA configuration.

MATERIALS AND METHODS

The study included 310 patients who underwent abdominal CT. On CT images, the aortomesenteric angle (AMA), the distance between SMA and aorta at three levels, and LLA were measured. Visceral fat volume was measured using three consecutive images obtained at the level of the umbilicus. The relationship among AMA, and distances measured between SMA and aorta, and visceral fat tissue volume were determined. The effect of LLA on AMA and distances measured between SMA and aorta was analyzed.

RESULTS

There was a significant positive correlation between visceral fat volume, and patient age, AMA, distances between SMA and aorta, LLA, and BMI (p<0.001). There were not any significant differences in AMA, distances between SMA and aorta, BMI, or visceral fat volume between the patients with an LLA of 20°-45° and those with an LLA >45° (p>0.05). There was a significant positive correlation between BMI, and AMA, distances between SMA and aorta (p<0.001). There was a significant positive correlation between visceral fat volume, and AMA, distances between SMA and aorta (p<0.001).

CONCLUSION

Visceral fat tissue volume is more valuable than BMI for evaluating the SMA configuration.

3D-Printed PEEK Extravascular Stent in the Treatment of Nutcracker Syndrome: Imaging Evaluation and Short-Term Clinical Outcome

Minimally invasive options are safe and reliable alternatives for the treatment of nutcracker syndrome (NCS). After continued efforts, our team successfully devised a new and effective therapeutic method: 3D-printed extravascular stenting of the left renal vein. From December 2017 to May 2019, 28 patients (25 men and 3 women) from different parts of China between 18 and 37 years old (mean, 23.6 years) diagnosed with NCS were admitted for laparoscopic 3D-printed extravascular stenting treatment. The post-operative follow-up duration was 6-24 months (median, 16.3 months). Technical success of the operation was achieved in all patients. After treatment, the NCS symptoms all patients resolved or improved during the follow-up period, without relapse. Most symptoms, including macro-/microhematuria, proteinuria, and flank/abdominal pain, tended to resolve within 3-6 months after the surgery; other symptoms, such as left-sided varicocele, also showed varying degrees of improvement at different times post-operatively. Perioperative complications were noted in two patients, including transient and mild lymphatic leakage, without any adverse effects. All extravascular stents were visualized on computed tomography and Doppler ultrasound scans, and no migration or any side effects occurred during the entire follow-up period. Compared to endovascular stenting or polytetrafluoroethylene artificial vessel procedures, 3D-printed polyetheretherketone extravascular stenting has more advantages in terms of stent design and rigidity and approach rationality while successfully preventing stent migration and thrombosis. Therefore, this method may serve as an accurate and effective treatment for NCS patients.

Doppler US and CT Diagnosis of Nutcracker Syndrome

Nutcracker syndrome (NCS) is a syndrome caused by compression of the left renal vein (LRV), between the abdominal aorta and the superior mesenteric artery, resulting in hypertension of the LRV and hematuria. Doppler ultrasonography (US) has been commonly used for the diagnosis of NCS. However, several technical issues, such as Doppler angle and sample volume, need to be considered to obtain satisfactory results. In addition, morphologic changes of the LRV and a jetting phenomenon across the aortomesenteric portion of the LRV on contrast-enhanced computed tomography (CECT) are diagnostic clues of NCS. With proper Doppler US and CECT, NCS can be diagnosed noninvasively.

Nutcracker Syndrome Accompanying With Superior Mesenteric Artery Syndrome: A Case Report

Purpose:

The duodenum and the left renal vein (LRV) occupy the vascular angle made by the superior mesenteric artery (SMA) and the aorta. When the angle becomes too acute, compression of either structure can occur. Although superior mesenteric artery syndrome (SMAS) and renal Nutcracker syndrome (NCS) share the same pathogenesis, concurrent development has rarely been reported.

Case report:

A 38-year-old female patient with a past history of gastrojejunostomy operated 6 years ago due to SMAS. She referred to vascular clinic with sever intermittent left-sided loin pain during the last 6 years. Computed tomography (CT)-angiogram and selective LRV angiogram with pressure gradient confirmed the diagnosis of NCS. She was treated by LRV transposition with uneventful recovery and considerable relief of symptoms.

Conclusions:

NCS accompanying with SMAS is quite unusual. A patient, who first presents with clinical evidence of SMAS, could also simultaneously or sometime thereafter present with NCS and vice versa.

Nutcracker Syndrome in Children: Role of Doppler Ultrasonographic Indices in Detecting the Pattern of Symptoms

The purpose of this study was to evaluate the clinical characteristics of 44 pediatric patients who were diagnosed as having nutcracker syndrome (NCS). We also investigated the left renal vein Doppler ultrasonography (DUS) results, to determine whether or not there was an association between clinical symptoms and DUS findings among these patients. The clinical data from 44 pediatric patients who were diagnosed as having NCS from January 2008 to December 2015 were retrospectively reviewed. We grouped the patients according to the presenting symptoms as symptomatic (loin pain; macroscopic hematuria or both) and non-symptomatic (microscopic hematuria and proteinuria were detected incidentally) and evaluated the left renal vein DUS indices in these two groups separately. Asymptomatic NCS was found in 27 (61.4%) patients; 21 (47.7%) of whom were admitted for the evaluation of proteinuria. The most frequent presenting symptoms were left flank pain (20.5%) and macroscopic hematuria (13.6%); and 2 (4.5%) patients presented with a combination of left flank pain and macroscopic hematuria. The mean ratio of the diameter of the hilar portion of the left renal vein (LRV) to that of the aortomesenteric portion was 4.36 ± 1.55. The mean ratio of the peak velocity (PV) between the two sites of the LRV was 7.32 ± 2.68 (3.1–15.6). The differences in the ratio of the diameters were statistically significant between the two groups and significantly higher in children with asymptomatic NCS (p = 0.025). The PV ratios of the LRV (p = 0.035) were significantly higher in asymptomatic children with NCS than in the symptomatic group. Our study identifies that increased compression ratio of the LRV entrapment is most observed in orthostatic proteinuria and microscopic hematuria.