1520 - A Case Report of May-Thurner Syndrome Causing Sciatic Mononeuropathy

Focal sciatic mononeuropathy in the setting of May-Thurner syndrome and iliofemoral deep venous thrombosis (DVT) 

Case Description:

A 27-year-old male was hospitalized for septic shock secondary to peritonsillar abscess. Hospital course was complicated by atrial fibrillation with rapid ventricular response, renal failure requiring hemodialysis, and respiratory failure requiring intubation. Patient experienced persistent left leg pain and weakness and was ultimately discharged home. Patient was re-admitted with worsening pain and difficulty with ambulation and was found to have atrophy of biceps femoris and weakness in knee extension. CT femur revealed left common iliac vein compression by right common iliac artery with associated left common iliac DVT. Electromyography and nerve conduction study confirmed a focal sciatic mononeuropathy distal to the biceps femoris, likely secondary to May-Thurner syndrome. Ultimately, he required stenting of left iliac vein and placement of inferior vena cava filter. 

 

Discussions:

May-Thurner syndrome is an uncommonly diagnosed condition wherein an anatomical variant –  the right common iliac artery compressing the left common iliac vein against the lumbar spine – can lead to decreased blood flow and venous congestion with an increased risk for DVT. May-Thurner syndrome has been shown to be present in over 20% of the population, however it is rarely considered in the differential diagnosis for patients with DVTs, especially if those patients have other risk factors for DVT. Given the structural characteristics of the compression, systemic anticoagulation alone is not effective at preventing DVT. Patients often require iliac vein stenting to prevent further compression, venous congestion, and thrombosis.

Conclusions:

This case potentiates the value of thorough differential diagnoses in patients with acute onset iliofemoral DVT, especially in the absence of other risk factors. Failure to identify etiology of DVT in a patient with May-Thurner syndrome could lead to chronic venous stasis, pulmonary emboli, or even iliac vein rupture if not corrected.