Intrathecal hematoma following epidural blood patch: An alternative mechanism to intrathecal puncture.

Intrathecal blood after a percutaneous epidural blood patch is a known complication, one that has been previously attributed to inadvertent needle tip position in the subarachnoid space. We present two cases with imaging confirmation of an alternative mechanism, one that includes blood transferring from the epidural space to the subarachnoid space through a pre-existing dural defect.