Absent Inferior Vena Cava Resulting in Exercise-Induced Epidural Venous Plexus Congestion and Lower Extremity Numbness A Case Report and Review of the Literature

Study Design. Case report and clinical discussion. Objective. To describe a unique etiology for a patient presenting with exercise-induced lower extremity numbness found to have agenesis of the infrarenal inferior vena cava (IVC) and a large vein draining the confluence of the iliac veins through the L4 foramen into the epidural plexus. Summary of Background Data. Epidural venous abnormalities are infrequently determined to be the etiology of nerve root compression syndromes. Such cases have been described in patients with absent IVC with thrombosis. We are unaware of any previously described cases of absent IVC with a primary route of venous return through the epidural venous plexus, resulting in symptoms in the absence of thrombosis. Methods. We describe a case of a 34-year-old man who presented complaining of numbness of legs as well as cauda equina symptoms occurring during exercise. He was found to have infrarenal absence of the IVC with the confluence of the iliac veins forming a large draining vein which entered the L4 foramen into the epidural venous plexus. Pre- and postexercise magnetic resonance imaging scans were performed to compare change in the size of the plexus. Results. Postexercise magnetic resonance imaging showed notable increase in the volume of the epidural venous plexus of the lower lumbar spine. The patient was referred to neurosurgery and vascular surgery, which did not intervene. On follow-up 2 years later, the patient developed significant right deep venous thrombosis and was found to be heterozygous for factor V Leiden mutation. Conclusion. This case demonstrates the breadth of anatomic and physiologic understanding a clinician must draw on when approaching patients with nerve root compression symptoms. It is also pertinent to consider performing a hypercoagulable work-up in patients with vascular deformations, as this may prevent future thrombosis.