September-October 2017

Intraforaminal Location of Thoracolumbar Radicular Arteries Providing an Anterior Radiculomedullary Artery Using Flat Panel Catheter Angiotomography

Gregg Pic

Lydia Gregg

We chose this research topic after noting that previous studies of the intraforaminal location of radicular arteries providing an anterior radiculomedullary artery (ARMA) were limited by 1) the field of view investigated, 2) the use of the cadaveric materials, or 3) the inability to specify whether the studied vessels were radicular branches providing an ARMA, a different artery, or even veins within the neural foramen. In contrast, the flat panel catheter angiotomography (FPCA) acquisitions that we reviewed for this study were performed in concert with diagnostic spinal angiography, which confirmed the presence of an ARMA in all of the included cases. This enabled us to investigate the position of radicular arteries providing an ARMA using multiplanar analysis of the border of the neural foramen in vivo.

Our study adds to the literature suggesting that thoracolumbar radicular branches that specifically provide an ARMA are generally located in the anterosuperior quadrant of the neural foramen. The data imply that using the posterolateral approach for transforaminal epidural steroid injections (TFESIs), which allows placing the needle tip away from the spinal cord arterial supply, may reduce the risk of injury to the spinal cord.

This study highlights misconceptions that have led to a slow rejection of the subpedicular or so-called “safe triangle” approach to TFESI—most importantly, the incorrect notions that the approach helps prevent vascular injuries in addition to nerve damage and that arterial opacification can be reliably detected during contrast injections performed prior to steroid injection.

We presented this study at the 54th Annual ASNR Meeting in Washington, D.C. A number of physicians approached us afterward to express that they had been performing TFESI using the subpedicular approach and were, until that point, unaware of the frequent presence of the spinal cord’s arterial supply within the targeted area. We also presented the work at the 71st Annual Association of Medical Illustrators Meeting and were contacted afterward regarding the anatomic value of the paper due to the frequent need for medical illustrators to produce illustrations for medical malpractice cases involving the neural foramen. We hope the study and the graphic illustrations accompanying the paper will continue to inform both physicians

and medical illustrators of the intraforaminal location of these important arteries.

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