Failure of epidural opioid to control cancer pain in a patient previously treated with massive doses of intravenous opioid

A patient with disseminated cancer pain failed to obtain pain relief despite the intravenous infusion of hydromorphone at a rate equivalent to over 7 g of morphine/day. Temporary pain relief occurred with an epidural injection of the local anesthetic lidocaine. Subsequently, the patient failed to obtain pain relief with a dose of epidural hydromorphone equivalent to approximately 3 g of morphine epidurally/day. At this time a syndrome of agitation, sweating, tachycardia and severe muscle cramps developed in the lower half of the body. After eliminating the possibility of spinal cord compression by diagnostic CT scanning, the patient was treated by reducing the dose of hydromorphone and adding local anesthetic, which provided pain relief but did not eliminate the severe muscle spasms and other symptoms. The addition of oral clonidine followed by clonidine dermal patch rapidly and completely eliminated the other symptoms, suggesting that the response was due to too rapid withdrawal of opioid. Maintenance of pain relief required the simultaneous administration of epidural bupivacaine and hydromorphone. A low-dose infusion of epidural bupivacaine was continued for more than 3 weeks and during this entire period the patient showed no evidence of motor or sympathetic block.