[Repeated inadvertent subdural catheterization: a case report].

We had a patient who had repeated inadvertent subdural catheterization. Eighty-two year old woman with post herpetic neuralgia had a continuous epidural anesthesia for the relief of pain. An epidural catheter was inserted at the Th 5-6 interspace using a paramedian approach. Fifteen minutes after 4 ml test dose of 1% lidocaine injection, she developed circulatory depressions and massive sensory block. The exact position of the catheter and the distribution of the local anesthetic agent were confirmed by radiographic contrast material. The catheter was observed in the subdural space. Anesthesia was therefore continued with an injection of 1.5 ml mepivacaine. After one month, epidural catheterization was done in the same patient. The catheter was inserted in subdural space again. The subdural injection has been implicated in a case in whom there has been extensive spread of an epidural block. The diagnosis of subdural block can be made by a subsequent injection of contrast medium, since an unusual clinical course might be seen. Subdural space has a poor blood supply, and injected medium may stay in this space for considerable period of time. Subdural catheterization in epidural anesthesia probably occurs more frequently than previously recognized.