Chronic contained rupture of an abdominal aortic aneurysm manifesting as lower extremity neuropathy

A 60-year-old man presented with intense right knee and thigh pain as well as weakness in his right lower extremity. Two months prior, he had sudden onset of severe low back pain and presented to his local physician, where he was diagnosed with lumbar spondylolisthesis. The back pain remitted soon thereafter, but he subsequently developed right knee and thigh pain. Upon presentation to our hospital, he denied having lower back pain or abdominal pain and had intact pulses in his lower extremities. His abdomen was soft and without tenderness, but a pulsating mass was palpated in the periumbilical region. Computerized tomography scan revealed an abdominal aortic aneurysm (AAA) with a large pseudoaneurysm (11-cm maximum diameter) posterior to the AAA (A, Cover). Magnetic resonance imaging showed destruction of the L3 and L4 vertebral bodies by the pseudoaneurysm (B). During open surgical repair, a large defect (6 cm 4 cm) of the posterior wall of the AAA was seen, and the eroded vertebral bodies were visualized through this defect (C). Orthopedic surgeons were consulted and deemed that vertebral repair was not required. Aneurysm repair was elected, using a knitted Dacron bifurcated graft, 16 mm 8 mm in size. The patient’s right knee and thigh pain remitted postoperatively, and the patient had an uneventful postoperative course. Contained retroperitoneal rupture is a rare presentation of ruptured AAA and can present with a variety of symptoms, including femoral neuropathy. The femoral nerve arises within the psoas major and emerges from its lateral border to run between the psoas major and the iliacus behind the iliac fascia. Thus, the location of the femoral nerves makes it vulnerable to compromise in the context of retroperitoneallycontained abdominal aortic rupture and may therefore result in symptoms of femoral neuropathy. Vertebral erosion is also reported as a complication of contained retroperitoneal rupture, usually accompanied by lower back pain. In this case, lower back pain was not prominent. Clinicians should consider this rare etiology in patients with isolated lower limb neuropathy of unexplained origin.