Keywords
nutcracker syndrome - varicocele - left renal vein transposition - sub-Saharan Africa
Introduction
Nutcracker syndrome (NCS) refers to clinical symptoms caused by extrinsic compression
of the left renal vein (LRV).[1]
[2] It exists in two anatomical variants: anterior nutcracker syndrome (ANCS), where
the LRV is compressed between the superior mesenteric artery (SMA) and the aorta,
and posterior NCS, where a retroaortic LRV is compressed between the aorta and the
vertebral column.[3] The clinical spectrum is highly variable and diagnosis typically requires clinical
and radiological evidence of LRV compression.[2]
[4]
Although frequently benign, symptoms can be severely debilitating, necessitating surgical
intervention in selected cases.[1] We present the first documented surgical case of ANCS in Benin, managed via LRV
transposition with favorable postoperative outcomes.
Case Presentation
A 16-year-old previously healthy male with a low body mass index (BMI) of 16.49 kg/m2 presented with a 7-month history of left testicular pain exacerbated by physical
exertion. Examination revealed a tender, visible varicosity of the anterior pampiniform
plexus and microscopic hematuria without proteinuria. Scrotal Doppler ultrasound demonstrated
left testicular hypotrophy and a grade 3 varicocele, with left-sided pampiniform plexus
dilation evident in the supine position and accentuated in the upright position. Abdominal
Doppler ultrasonography performed in both supine and upright positions showed near-complete
narrowing of the LRV at the aortomesenteric clamp, with a characteristic “beak sign.”
The hilar-to-aortomesenteric LRV diameter ratio was 8, and the peak velocity ratio
between the aortomesenteric and hilar portions was 5. No dilation or abnormal flow
was noted in the inferior vena cava (IVC) or iliac veins. Contrast-enhanced abdominal
computed tomography (CT) angiography ([Fig. 1]) confirmed the diagnosis of ANCS, revealing an SMA aortic angle of 11 degrees, the
“beak sign,” and a hilar-to-aortomesenteric LRV diameter ratio of 6.5. The left gonadal
vein was dilated. Renal function tests were within normal limits. Initial conservative
management consisted of analgesics and nutritional support aimed at weight gain, administered
over 4 months. Symptoms worsened with pelvic pain and persistent microscopic hematuria.
Fig. 1 Contrast-enhanced computed tomography (CT) images showing anterior nutcracker syndrome.
The sagittal view demonstrates a narrowed aortomesenteric angle, and the axial view
reveals the classic “beak sign” due to compression of the left renal vein (LRV).
The patient underwent surgery via a midline supra- and infraumbilical laparotomy under
general anesthesia. Following systemic heparinization, lateral clamping of the IVC
was performed, and the LRV was transected and reimplanted 3-cm caudal to its original
insertion ([Fig. 2]). Postoperative anticoagulation with enoxaparin was administered for 72 hours. The
postoperative course was uneventful. Immediate Doppler ultrasound confirmed satisfactory
LRV patency without thrombosis, distortion, or stenosis. The patient was discharged
on postoperative day 8.
Fig. 2 Intraoperative images of left renal vein (LRV) transposition onto the inferior vena
cava (IVC). (A) Initial anatomical insertion site of the LRV before transposition. (B) Reimplanted LRV anastomosed to the IVC, 3-cm inferior to its original insertion
site.
At the 24-month follow-up, the patient reported no recurrent pain or testicular swelling.
Computed tomography angiography (CTA) showed no residual compression of the LRV by
the SMA, nor any evidence of intrinsic stenosis.
Discussion
Initially described anatomically by Grant in 1937 and later identified in humans by
El Sader and Mina in 1950, the term “nutcracker syndrome” was coined by de Schepper
in 1972. Its true prevalence remains unknown due to frequent asymptomatic presentation
and diagnostic ambiguity. It typically affects young to middle-aged adults, with a
slight female predominance (53.6%).[1]
[4] Several studies have reported an association between BMI and NCS.[1] Our patient, with a BMI of 16.49 kg/m2, supports this correlation.
NCS is often a diagnosis of exclusion.[2] Common presenting symptoms include microscopic hematuria (69.5%), flank or abdominal
pain (48.4%), pelvic pain (23.1%), and varicocele (15.8%)[2]—all of which were present in our patient.
ANCS diagnosis relies on multiple imaging modalities, including Doppler ultrasonography,
CTA, magnetic resonance angiography (MRA), intravascular ultrasound, and venography
with pressure gradient measurement.[1]
[2]
[4] Doppler ultrasonography is the first-line imaging modality for diagnosing nutcracker
syndrome (NCS), due to its accessibility, safety, and real-time hemodynamic assessment.
The key parameter is the peak systolic velocity ratio between the aortomesenteric
and hilar segments of the LRV. Diagnostic thresholds are ≥5.0 in adults (80% sensitivity,
94% specificity) and ≥4.7 in children (100% sensitivity, 90% specificity). Accurate
measurement requires optimizing the insonation angle (ideally 30–60 degrees) and adjusting
sample volume to fully include the SMA segment. Color Doppler enhances diagnostic
confidence by visualizing aliasing high-velocity jet flows. A Doppler-derived pressure
gradient > 3 mm Hg is considered pathognomonic.[5] CTA and MRA are valuable for visualizing LRV compression, gonadal vein dilation,
and pelvic congestion. A hilar-to-aortomesenteric LRV diameter ratio >4.9, “beak sign,”
and an SMA–aortic angle <35 degrees are highly suggestive.[2] In our case, combined Doppler ultrasound and CTA enabled accurate diagnosis, in
line with existing literature.[4] Furthermore, CTA was selected over MRA despite its ionizing nature, due to the unavailability
of magnetic resonance imaging in our setting.
Management of ANCS is debated due to the absence of consensus guidelines. Therapeutic
decisions depend on symptom severity. Conservative management is favored in patients
with mild symptoms (e.g., microscopic hematuria, orthostatic proteinuria), particularly
those under 18, as growth may alleviate LRV compression through increased retroperitoneal
fat and connective tissue.[1]
[2] This approach includes diet (notably weight gain), analgesia, and clinical monitoring.
Its aim is to relieve clinical symptoms and prevent potentially severe complications
such as chronic anemia or thrombosis of the LRV. Wang et al. reported favorable outcomes
with conservative therapy in two-thirds of patients.[6] Similarly, Sarikaya et al., in a prospective study involving 16 patients with moderate
symptoms followed for a median duration of 27.3 months, observed complete symptom
resolution in 28.5% of cases and improvement in 31.4%, despite the absence of significant
changes in imaging parameters.[7] Surgical intervention is reserved for refractory or severe cases and can be performed
via open or minimally invasive approaches. In our patient, surgery was warranted due
to persistent disabling pain after 4 months of conservative therapy and the infertility
risk linked to varicocele. This risk is supported by studies showing impaired spermatogenesis
in NCS-related varicocele and significant fertility improvement after microsurgical
spermatic–inferior epigastric vein anastomosis, with natural conception achieved in
80% of cases.[8]
Among available surgical options, open approaches—particularly LRV transposition—are
still regarded as the reference standard for the definitive management of ANCS. Other
procedures such as nephropexy, renal autotransplantation, or gonadocaval bypass have
also been described, but with more limited data. LRV transposition has shown durable
results, with a low incidence of major perioperative complications and a favorable
safety profile. In the Mayo Clinic series, there were no reported cases of renal failure
or mortality, and early symptom recurrence was uncommon (8.3%), mainly due to LRV
restenosis or occlusion, which were effectively managed by secondary interventions.
Over a mean follow-up of 36.8 months, the reintervention rate reached 22.2%, while
patency rates at 24 months remained high (74% primary, 97% primary-assisted, 100%
secondary).[2]
[3]
Endovascular techniques, such as LRV stenting and gonadal vein embolization, are less
invasive and preserve renal perfusion with faster recovery. However, their long-term
safety—especially in younger patients—remains uncertain. Complications like migration
(up to 6.6%), fracture, or occlusion may require surgical retrieval. Despite over
90% technical success and symptom relief, these risks, along with the lack of dedicated
venous stents and limited follow-up, restrict their use in pediatric populations.[2]
[4]
Laparoscopic extravascular stenting is a promising minimally invasive option, offering
direct operative control without LRV clamping. Small series report favorable hemodynamics
and symptom relief, although evidence remains limited and rare complications, such
as stent migration, have been noted.[2]
In our patient, the absence of symptoms 2 years after surgery, along with preserved
renal function and no radiological evidence of residual compression, aligns with the
existing literature and further supports the feasibility and efficacy of LRV transposition
in resource-limited setting.
Conclusion
Nutcracker syndrome is a rare and often underdiagnosed vascular compression disorder
with variable clinical presentations. While multiple therapeutic options exist, open
surgical transposition of the LRV remains the gold standard in selected cases. This
case highlights the efficacy and safety of open LRV transposition in sub-Saharan African
settings and adds to the global experience of nutcracker syndrome management.
