Dural puncture and subdural injection: a complication of lumbar transforaminal epidural injections.

CASE REPORT Two cases are presented in which the complication of dural puncture is documented in the context of a lumbar transforaminal epidural steroid injection. The hazard of dural puncture during transforaminal epidural injections, the anatomy of the dural and thecal sac, the potential for subdural injections, and relevant literature are reviewed. DESIGN Report of two cases. BACKGROUND Lumbar transforaminal epidural steroid injections are a commonly employed procedure for the treatment of lumbar radiculopathy. The optimal target point lies at the "6 o' clock" position of the pedicle. Contrast is injected to confirm proper placement of the needle and correct flow of the medication through the epidural space. Despite apparent proper placement of the needle, a potential complication exists of puncturing the dura while performing this procedure. Spinal injectionists should recognize the subsequent contrast patterns associated with this complication. CONCLUSION Subdural and intrathecal spread of contrast is rarely seen with transforaminal injections and thus can be easily overlooked. Becoming familiar with the images presented in these cases may help alert the interventionalist of a dural puncture, and thus avoid injection of medications into the intrathecal and subdural spaces.