Intraspinal drug infusion employs an infusion device, such as the Medtronic or the Arrow implantable pumps, to internally administer the opioid morphine into the intrathecal or epidural spaces of the spinal column.  It often reduces many of the side effects (nausea) associated with oral drug administration. Morphine, which binds to neuro-receptors to inhibit the transmission of pain signals, has historically been one of the most important drugs used for treating pain. 

Both SCS and intraspinal drug infusion are implantable therapies—in one a pulse generator is implanted with a small wire to deliver electrical impulses; in the other a drug pump is implanted with a small-diameter tube to precisely deliver controlled doses of medication.

The ideal patient for an implantable treatment is one who has not responded well to more conservative therapies, but who experiences a significant amount of pain relief in a test of SCS or intraspinal drug infusion.  SCS is often used with patients who have damage to the nerves--for instance, continued pain following back surgery.  Intraspinal drug infusion is used primarily for patients with severe side effects to oral pain medications, or for cancer pain.