Treating chronic pain with intraspinal drug infusion.
Chronic pain is constant or recurring pain that lasts longer than six months.
This web page discusses one implantable therapy, intraspinal drug infusion, which may be appropriate for chronic pain when conservative treatments fail.

What is intraspinal drug infusion therapy?
Intraspinal drug infusion is an implantable therapy which blocks pain by administering small doses of morphine directly to the spinal cord. Intraspinal drug infusion requires much smaller doses of morphine for pain relief than with oral (pills) or intravenous (I.V.) methods. Patients may have fewer side effects and greater pain relief.

Who is a candidate for drug infusion therapy? Patients with severe, chronic pain in broad areas of the body, either from cancer or other causes,)may benefit from intraspinal drug infusion therapy. Most patients have unsuccessfully tried other pain control methods. While their pain may respond to oral drug therapy, they either do not achieve adequate pain relief or cannot tolerate the side effects of the pain drug at effective doses.

An intraspinal drug infusion system consists of a pump and spinal catheter implanted under the skin.

What is an intraspinal drug infusion system?
An intraspinal drug infusion system consists of a pump and catheter. The pump is a round metal disk about one inch thick and three inches in diameter. It weighs about six ounces. The pump stores and releases prescribed amounts of morphine into the spinal canal. The pump can be refilled by inserting a needle through the patient's skin into a filling port in the center of the pump. The catheter is a flexible tube that delivers the morphine from the pump to the spinal canal.

How does the doctor know if a drug infusion system will work?
Selected candidates for this therapy undergo a trial of intraspinal drug therapy. During this trial, the physician injects a small dose of morphine into the spinal canal to determine whether the pain can be diminished with this treatment. This procedure is not uncomfortable for the patient. Patients who experience significant pain relief during the trial may have a drug infusion pump and catheter implanted.

Where and how is the pump implanted?
The drug pump is surgically placed just underneath the skin usually in the lower abdominal area. The spinal catheter is inserted through a needle into the spinal canal. The other end of the catheter is placed under the skin and connected to the pump. The pump is filled with the morphine prescribed by the physician.

How is the medication dispensed?
Some drug infusion systems dispense at a steady rate, with the dosage determined by the concentration of the medication injected into the pump reservoir. Medication changes in steady-rate systems are accomplished by withdrawing the old strength of medication and reinfusing the new strength drug.

With a programmable pump, a tiny motor moves the medication from the pump reservoir through the catheter. Adjustments in the dose, rate, and timing of the medication can be made using an external programmer. This allows greater flexibility for matching the dosage of pain relief medication with patient needs.

An implanted drug pump delivers very small doses of morphine through the catheter to the spinal canal. With intraspinal drug infusion therapy, pain relief can be achieved with much smaller doses of morphine than would be required with oral or intravenous methods.

What can be expected from intraspinal drug infusion therapy?
Patients can expect good to excellent pain relief if they had a successful trial. Patients will need to return to their physician's office for pump refills and adjustments to their medication (approximately every
four to 12 weeks). Compared with intravenous (I.V.) drug infusion or oral medications, intraspinal drug infusion usually controls pain with much smaller dosages because the drug is delivered directly into the intraspinal space. With this delivery method, therapeutic benefits are maximized and side effects are minimized. Benefits of intraspinal drug infusion therapy may include a more active lifestyle, better sleep, and reduced need for oral pain medications.

Is addiction a concern with intraspinal drug infusion therapy?
This is a very rare, unlikely outcome. Research has shown that fewer than one in 1,000 patients becomes "addicted" to morphine with intraspinal drug infusion therapy because the dose required for pain control is so small. Addiction refers to compulsive drug-seeking behavior and using pain medication for emotional gratification. Patients in pain rarely get addicted because they use morphine to control pain, not for emotional gratification.

Ask Your Doctor.
Patients whose chronic pain has not responded to more conventional treatment may be considered by their physician for intraspinal drug infusion therapy. If you have questions regarding this treatment, feel free to discuss them with our office.