Injectate Volumes Needed to Reach Specific Landmarks in Lumbar Transforaminal Epidural Injections

ObjectivesTo identify the volumes of contrast material needed to reach specific landmarks during lumbar transforaminal epidural injections (L-TFEIs).DesignProspective, nonrandomized, observational human study.SettingAcademic/private pain management practice.PatientsSixty-nine patients undergoing L-TFEIs were investigated. Sixty patients were included in this study.InterventionsL-TFEIs were performed with the use of contrast-enhanced fluoroscopic visualization.Main Outcome MeasurementsAfter the appropriate spinal needle position was confirmed, up to 5.0 mL of nonionic contrast material was slowly injected. Under biplanar fluoroscopic guidance, contrast volumes were recorded as flow reached specific anatomic landmarks: ipsilateral neural foramen, ipsilateral disks superior and inferior to the injected level, and across the midline of the spinous process.ResultsAfter 1.1 mL of contrast was injected, 100% of L-TFEIs spread to the medial aspect of the superior pedicle (PED) of the corresponding level of injection. After 2.8 mL of contrast was injected, 95% of L-TFEIs spread to the superior aspect of the superior intervertebral disk (IVD) of the corresponding level of injection. After 3.6 mL of contrast was injected, 95% of L-TFEIs spread to the inferior aspect of the inferior IVD of the corresponding level of injection. After 3 mL of contrast was injected, 88% of L-TFEIs spread to cover both the superior and inferior IVDs of the corresponding level of injection. After 4 mL of contrast was injected, 93% of L-TFEIs spread to cover both the superior and inferior IVDs of the corresponding injection. After 4 ml of contrast was injected, 55% of L-TFEIs spread beyond the midline of the spinous process, but barely.ConclusionThis study demonstrates injectate volumes needed to reach specific anatomic landmarks in L-TFEIs. A volume of 4.0 mL of injectate reaches both the superior aspect of the superior IVD and the inferior aspect of the inferior IVD 93% of the time.