The use of intraspinal opioids is an excellent alternative for patients obtaining poor relief with other techniques or who experience excessive side effects.Epidural and subarachnoid opioids offer pain relief with substantially lower total doses of opioids and fewer side effects, Continuous infusion techniques reduce drug requirements (compared with intermittent boluses), minimze side effects, and decrease the likelihood of catheter occlusion. Mycoclinic activity may be occassionally observed with intrathecal morphine or hydromorphone.

Epidural or intrathecal catheters can be placed percutaneously or implanted to provide long-term effective pain relief. Tunneling the catheters reduces the risk of infection. Epidural catheters can be attached to light-weight external pumps that can be worn by ambulatory patients. A temporary catheters must be inserted first to access the potential efficacy of the technique. Correct placement of the permanent catheters should be confirmed by fluoroscopy and radiocontrast. Completely implantable intrathecal catheters with externally programmable pumps can also be used for continuous infusion; their major disadvantage is cost. The reservoir of the implanted pump is periodically refilled percutaneously; an additional injection port allows injection into the catheters directly.

Implantable intrathecal systems are most appropriate for patients with a life expectancy of several months, whereas tunneled Epidural catheters are appropriate for patients expected to live for only weeks. Formation of an inflammatory mass at the tip of the catheters can occur and may reduce efficacy. The major problem with intraspinal opiods is tolerance. Generally a slow phenomenon, tolerance does develop rapidly in some patients. In such instances, adjuvant therapy may be used, including the intermittent use of local anesthetics or a mixture of opioids with local anesthetics. Clonidine is particularly useful for neuropathic pain. In high doses, is more likely to be associated with hypotension and bradycardia. Complications include local skin infections and Epidural abscess. Superficial infections can be reduced by the use of a silver-impregnated cuff close to the exit site. Other complications include hematoma, which may be immediate or delayed onset (days). The use of invasive Spinal techniques can be complicated by increased intracranial pressure. The risk-benefit ratio must be weighed carefully in terminal patients.