Subdural air collection: a likely source of radicular pain after lumbar epidural.

This case conference reports two cases of epidural anesthesia in which air was used to identify the epidural space during a loss-of-resistance placement technique. Both patients subsequently complained of severe pain and subdural air was demonstrated in case 1 by computed tomography and in case 2 by magnetic resonance imaging. The possible causes of the pain syndrome experienced by both patients are discussed.