Spinal Care, Neurology, Spinal Medical Advice and Information.

Interventional Pain Management

by Chester Pruett, MD

Intervening at the spinal cord level for pain management is divided into three general categories. One category is effecting pain relief at the spinal cord level by the use of electrical stimulation. A second category is using medications at the spinal cord level. The third spinal cord intervention would involve a surgical manipulation of the spinal cord itself to obtain pain relief.

Electrical stimulation of the spinal cord, also known as dorsal column stimulation (DCS), was first done effectively in the 1970s by placing wire electrodes into the epidural space and attaching them to a pulsed generator. The equipment used was crude and would usually be effective for a few days to weeks before failing. In 1983, commercial sources became available for the equipment that made it much more durable and reliable. DCS for controlling chronic low back pain and/or leg pain was a nondestructive, reversible procedure that has become an attractive alternative for patients who may be facing or have already experienced neuroablative procedures or habituating opioid medications.

The exact mechanism of action of DCS is unknown. Electrical stimulation of the spinal cord interferes with the conduction of pain impulses through certain sensory pathways and provides pain relief without changing any underlying pathology.

The procedure is usually done in two stages. The trial stage is done by placing one or more electrodes into the epidural space, usually by a percutaneous approach. The electrodes are attached to an external generator and pain relief recorded for one to five days. If successful, a permanently implanted generator and electrodes are done at a later date.

DCS is still considered experimental or investigational for a variety of conditions to include occipital neuralgia, intercostals neuralgia, phantom limb pain and post-herpetic neuralgia. It has been used to treat the failed neck syndrome, cervicogenic headache and intractable angina, but continues to await FDA approval for these conditions.

The second category of intervention places medications directly into the spinal fluid. This is most commonly done by placing a catheter into the spinal fluid and attaching it to an implanted pump. The most common medication used is morphine sulfate, hence the term “Morphine Pump.” Because most opiate receptors are located in the spinal cord and brain, this is a very efficient method for delivering opioid medications. About one one hundredth the intramuscular dose in the spinal fluid is equipotent for most opioids. Other medications such as clonidine, baclofen, and ziconitide have also been very effective in the spinal fluid at relieving certain types of pain.

Morphine pumps generally are approved for cancer or malignant pain. They are used less often for benign pain due to a specific complication caused by long term catheter implantation in the spinal fluid. Over a long enough time frame, the catheter can form a granuloma in the spinal fluid which can cause a paralysis below the level of the catheter.

Surgical interventions of the spinal cord include a cordotomy and sensory rhizotomy. These procedures are done very effectively by neurosurgeons in certain selected patients.

In conclusion, DCS and spinal opiates have provided newer, less invasive options for the treatment of certain pain conditions. They have been proven to be cost-effective and in certain patients, a most reasonable approach to pain management.

Chester Pruett, MD is a graduate of LSU School of Medicine in New Orleans. He completed residency training at Brooke Army Medical Center. After seven years of active duty in the Army, he established an office in the Oak Hills area. For the last 25 years he has lived and worked in the Methodist Hospital and Oak Hills area with his wife Carolyn Pruett and their two daughters.