The Retrodural Space of Okada Accessed During Cervical Transforaminal Epidural Steroid Injection

The retrodural space of Okada is a potential space that lies between the anterior surface of the vertebral lamina and the posterior surface of the ligamentum flavum, which may also offer a communication between ipsilateral adjacent facet joints, contralateral facet joints and the interspinous ligament. Access of the space of Okada and contrast filling patterns have been described in the literature during various spinal injections, but to our knowledge not during a cervical transforaminal injection [1, 2]. The following images were obtained while performing a left C6–C7 transforaminal epidural steroid injection. During the procedure, the retrodural space of Okada was incidentally accessed and visualized following injection of contrast medium, which also revealed a communicating interspinous bursa. Given known anatomy, needle placement posteriorly at the upper or mid-foraminal level may increase the chance of accessing the retrodural space of Okada via the facet joint capsule at the superioanterior...