Robert M. Levy, M.D., Ph.D.
Neurosurgeon; President, International Neuromodulation Society; Editor-in-Chief, Neuromodulation: Technology at the Neural Interface
Chronic pain is one of the most significant causes of disability and loss of quality of life throughout the world. A significant majority of patients fail to respond to non-opioid medications, and chronic opioid therapy is both ineffective and dangerous, often resulting in tolerance, addiction, and even death.
Neuromodulation therapies, including but not limited to techniques like spinal cord (SCS), dorsal root ganglion (DRGS) and peripheral nerve stimulation (PNS), intraspinal drug administration (IDDS), and non-invasive techniques like transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) have, on the other hand, been highly successful in treating chronic pain with a remarkable safety profile.
The great effectiveness and low rate of complications are the result of technical advances over the past 20 years. Contemporary neurostimulation techniques are expected to provide 50 percent or greater pain relief in 80 percent or more patients, while 70 percent of patients can be expected to obtain 80 percent pain relief or more. The devices are quite robust, with excellent results reported for several years.
Unlike other procedures, neuromodulation techniques are tested prior to device implantation. Thus, patients know how well the device will work before the permanent procedure.
The trial of SCS or DRGS uses needles to introduce stimulation leads into the epidural space, like the insertion of an epidural catheter during labor and delivery. For PNS, the wires are placed through needles and placed next to the involved nerve(s). Wires are attached to an external battery and taped to the skin. Patients then test the system for several days to determine whether it provides sufficient relief to warrant the permanent implant.
For the permanent procedures, a small incision is made and new sterile wires are placed and run under the skin to a second incision where the battery is placed. Conventional batteries (requiring replacement at the end of life), rechargeable batteries (which have battery lives of 10 years or more), and even wireless systems with external batteries are available based upon individual patient needs.
Non-invasive stimulation techniques, which involve placing a magnetic coil or electrical source over the brain region(s) to be stimulated, are currently undergoing development and careful investigation to see if they can be used to provide similar degrees of pain relief in chronic pain patients.
In light of the factors noted above, neuromodulation techniques can be an important and effective tool in the treatment of chronic pain.