Abstract ID: A4
Abstract Title: Anatomy of the Cervical Radicular Arteries: Implications for Cervical Transforaminal Injection
Poster Type: Either
ABSTRACT BODY
Introduction: Rare, catastrophic spinal cord infarction has been reported after cervical transforaminal injection of steroid (CTFIS).(1-3) Steroid injection into a radicular artery is the proposed mechanism; the steroid serving as an embolus, occluding vessels to the spinal cord and leading to major neurological sequelae. We performed a cadaveric dissection to elucidate the anatomy of the radicular artery and propose modifications to the technique for CTFIS to minimize the risk of intraarterial injection.
Methods: After IRB approval, a cadaver was injected with latex to aid in arterial visualization. Prior to death, this patient had undergone vertebral arteriography. These arteriograms were utilized to determine the course of the radicular artery through the intervertebral foramina. Removal of the vertebral bodies and anterior portion of the dura mater allowed visualization of the anterior spinal artery, which was then traced from the spinal cord through the foramina.
Results: In this specimen, three radicular arteries enter the foramina adjacent to the left C5, right C6 and right C8 nerve roots to join the anterior spinal artery. Two enter adjacent to both C7 roots to supply the posterior spinal arteries. The right C7 and C8 radicular arteries enter the lateral aspect of the foramina and penetrate the dural sleeve within the inferior foramina, below the exiting nerve root. Both arteries follow a tortuous course within the foramina. The radicular artery entering on the right at C8 arises from the subclavian artery and is large enough to be punctured by a 22 g needle (Fig 1). The right C6 radicular artery seen on angiography (Fig 2) arises from the vertebral artery.
Discussion: This study was limited to dissection of one specimen; yet, several important findings can be applied to CTFIS. Radicular arteries joining the anterior spinal artery to perfuse the spinal cord enter the cervical foramina at numerous vertebral levels on both sides of the neck. The caliber of many of these vessels is larger than a 22 g needle. Radicular arteries enter the foramina just inferior to the exiting nerve root and follow a tortuous course along the inferior and anterior aspect of the root until penetrating the dura to join the anterior or posterior spinal artery. Radicular arteries arising from the vertebral artery lie over the most anteromedial aspect of the foramina, while those arising from the deep or ascending cervical arteries traverse the entire extent of the foramina. Radicular arteries arising from the deep and ascending cervical arteries are of greatest clinical significance because they course through the entire foramen. A transforaminal technique with needle placement parallel to the axis of the exiting nerve root along the posterior most aspect of the foramen, midway from the inferior to superior limits of the foramen will avoid the most common locations of the radicular arteries. The needle should pass no more than half way from the lateral to medial extent of the foramen to avoid the risk of penetrating the vertebral artery and its radicular branches.
References: 1. Anesthesiology 2004;100:1595-600.; 2. Pain 2003;103:211-5.; 3. Pain 2001;91:397-9.
ATTACHED FILES
Reg Anesth Pain Med 2004; 29(2):A4