Working Diagnosis:
The working diagnosis was congenital absence of the inferior vena cava with extensive iliac and femoral venous thrombosis, collateral venous engorgement, and secondary lumbar nerve root compression causing left-sided radiculopathy.

Treatment:
After the vascular abnormality was recognized, interventional radiology was consulted for endovascular management. Interventional radiology performed venography Case Photo #3 followed by bilateral lower extremity venous thrombectomy for occlusive thrombi involving the superficial femoral, common femoral, external iliac, and lumbar venous systems. This was followed by inferior vena cava and bilateral common iliac vein reconstruction with stent placement Case Photo #4 . After endovascular treatment, the patient completed six months of clopidogrel and will continue on lifelong anticoagulation with apixaban.

Outcome:
The patient improved after endovascular treatment. His low back pain and left leg weakness resolved, and motor strength returned to normal. He gradually resumed his routine daily activity. Further laboratory evaluation included extensive hypercoagulability workup by hematology which was unrevealing and did not identify a separate inherited thrombophilia. Follow-up imaging showed patent stents without recurrent thrombosis. Ongoing management is focused on stent patency, prevention of recurrent thrombosis, and surveillance for return of neurologic or vascular symptoms.

Author's Comments:
Congenital absence of the IVC is rare, but it can become clinically significant when venous return from the lower body is redirected through collateral pathways. These collateral veins may enlarge under pressure and may become thrombosed. When they form near the lumbar spine and pelvis, they can compress or irritate adjacent nerve roots and create a radicular pattern that resembles a classic syndrome of disc disease.

This case is memorable because of its typical sports medicine presentation with a spine-related complaint, but it evolved into a vascular problem that could have easily been overlooked. It is an important reminder that young age does not always equate to benign back pain, and a normal-appearing lumbar disc does not conclude the diagnostic workup when the patient has significant exam findings such as motor weakness.

The most important turning point in this case was respecting the discrepancy between the patient's symptoms and the initial findings. Furthermore, in this patient, the absence of leg swelling and pre-existing thrombophilia made the final diagnosis even easier to miss. In practice, that means slowing down when the expected or most likely explanation does not fully fit the clinical presentation. For clinicians evaluating athletes, laborers, and active young adults, this case reinforces a simple but important point: treat progressive radiculopathy seriously, scrutinize the imaging, and consider extraspinal causes on the differential diagnosis when the usual suspects are absent.

Editor's Comments:
This case illustrates an interesting clinical presentation of lumbar radiculopathy with a twist that includes significant impacts on management. Lumbar radiculopathy related to disc disease is common. Other pathologic conditions causing nerve root compression should also be included in the differential diagnosis for radiculopathy (e.g., displaced bony fragments, synovial cysts, epidural hematoma or abscess, neoplastic processes) and are generally elucidated by magnetic resonance imaging. Vascular anomalies resulting in epidural varices are equally important but relatively rare causes of lumbar radiculopathy. Similar to the case reported by Floman et al (2007), it may be hypothesized that obstruction of the inferior vena cava and other deep venous structures resulted in flow- and pressure-related changes in the valveless epidural vessels. The proximity of these dilated vessels to neural structures then caused nerve root compression mimicking other more common causes of lumbar radiculopathy but requiring CT imaging for diagnosis.

The authors are commended for pursuing an alternative diagnosis when their initial suspicions were disproven. Cognitive bias in medicine refers to systematic errors in clinical reasoning that lead to diagnostic error. The ability to shift gears and “slow down” in an effort to avoid cognitive bias and encourage a more deliberate diagnostic approach in this case led the authors to pursue additional imaging which confirmed a primary vascular condition. Their diligence afforded the patient a timely diagnosis and management with an optimal short-term outcome.

References:
1. Lambert M, Marboeuf P, Midulla M, Trillot N, Beregi JP, Mounier-Vehier C, Hatron PY, Jude B. Inferior vena cava agenesis and deep vein thrombosis: 10 patients and review of the literature. Vasc Med. 2010;15(6):451-459.

2. Floman Y, Smorgick Y, Rand N, Bar-Ziv J. Inferior vena cava thrombosis presenting as lumbar radiculopathy. Am J Phys Med Rehabil. 2007;86(11):952-955.

3. Hallan DR, McNutt S, Reiter GT, Thamburaj K, Specht CS, Knaub M. Dilated epidural venous plexus causing radiculopathy: a report of 2 cases and review of the literature. World Neurosurg. 2020;144:231-237.

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