Exaggerated epidural blockade resulting from unusual spread of bupivacaine in a patient with low back pain.

A 75-year-old woman with chronic low back pain was given bupivacaine and methylprednisolone epidurally through a catheter in the L1-L2 interspace. An unusual spread of bupivacaine resulted in a block from the C4 to the L1 dermatome with no relief of back pain. Injection of a radiopaque dye and subsequent X rays showed a similar spread. The possible causes are discussed.