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Abrupt Onset Of Lower Extremity Paralysis After Infrarenal Abdominal Aortic Aneurysm Repair, A Case Of Spinal Cord Infarct 2014

Category General Spine Sayf Al-katib, MD Joe Harb, DO Ay-Ming Wang, MD Purpose Spinal cord infarction has a variety of etioliogies including vascular, traumatic and iatrogenic processes. A devastating complication of infrarenal aortic surgery, spinal cord infarct has been reported to have a 0.1-0.9% incidence. In this presentation, we present the MRI findings of acute spinal cord infarct after elective repair of an infrarenal abdominal aortic aneurysm. We will briefly review spinal cord anatomy and vascular supply and correlate imaging findings with clinical symptamotology. Materials & Methods A 77 year old caucasian male with past medical history of hypertension, coronary artery disease, chronic kidney disease and abdominal aortic aneurysm presented for elective repair of an infrarenal abdominal aortic aneurysm. The patient underwent elective repair via retroperitoneal approach as extension of the aneurysm was not amenable to an aortic endograft repair. Estimated blood loss during the procedure was three liters. The operative course entailed aortic clamping with 40 minutes of warm ischemia time. In the immediate postoperative period, the patient was noted to have lower extremity paralysis. An MRI of the thoracic spine was requested to evaluate for spinal cord insult. Axial and sagittal T1, T2 and DWI and sagittal STIR sequences of the thoracic spine was obtained approximately 9 hours after completion of surgery. Results T2 wieghted images show focal abnormal increased signal with expansion of the spinal cord at the conus medullaris over a three vertebral body segment length. Axial images demonstrate the signal abnormality limited to the central gray matter with an "owl eye" appearance. Diffusion weighted images show prominent focal restricted diffusion in the same distribution. The patient continued to have lower extremity paralysis after surgery; however, the patient had preserved sensation to light touch and proprioception. Conclusion Spinal cord infarct is a rare but devastating complication of aortic surgery. MRI with diffusion weighted imaging can provide a specific diagnosis when infarction is clinically suspected. Loss of motor function with preserved sensation is characteristic of gray matter infarct with sparing of the white matter tracts. Characteristic MRI findings of spinal cord infarct include abnormal T2 signal hyperinstensity in an "owl eye" distribution of the gray matter with cord expansion. If there is suspicion for spinal cord infarction, diffusion wieghted imaging should be included as part of the imaging protocol. References Cheshire WP et al: Spinal cord infarction: etiology and outcome. Neurology. 47(2): 321-30, 1996. Weidauer S et al: Spinal cord infarction: MR imaging and clinical features in 16 cases. Neuroradiology. 44(10): 851-7, 2002 Masson C et al: Spinal cord infarction: clinical and magnetic resonance imaging findings and short term outcome. J Neurol Neurosurg Psychiatry. 75(10):1431-5, 2004 Hobai IA et al: Perioperative spinal cord infarction in nonaortic surgery: report of three cases and review of the literature. J Clin Anesth. 20(4):307-12, 2008 Thurnher MM et al: Diffusion-weighted imaging, diffusion-tensor imaging, and fiber tractography of the spinal cord. Magn Reson Imaging Clin N Am. 17(2):225-44, 2009 Mommertz G et al: Brain and spinal cord protection during simultaneous aortic arch and thoracoabdominal aneurysm repair. J Vasc Surg. 49(4):886-92, 2009 Cheng MY et al: Concomitant spinal cord and vertebral body infarction is highly associated with aortic pathology: a clinical and magnetic resonance imaging study. J Neurol. 256(9):1418-26, 2009 Yuh WT, Marsh EE 3rd, Wang AK, Russell JW, Chiang F, Koci TM, Ryals TJ. MR imaging of spinal cord and vertebral body infarction. AJNR Am J Neuroradiol. 1992 Jan-Feb;13(1):145-54. Rovira A, Pedraza S, Comabella M, Alvarez J, Salgado A. Magnetic resonance imaging of acute infarction of the anterior spinal cord. J Neurol Neurosurg Psychiatry. 1998 Feb;64(2):279-81. Sibon I, Ménégon P, Moonen CT, Dousset V. Early diagnosis of spinal cord infarct using magnetic resonance diffusion imaging. Neurology. 2003 Dec 9;61(11):1622. Bammer R, Fazekas F, Augustin M, Simbrunner J, Strasser-Fuchs S, Seifert T, Stollberger R, Hartung HP. Diffusion-weighted MR imaging of the spinal cord. AJNR Am J Neuroradiol. 2000 Mar;21(3):587-91.