From the Lab
By Ted Swing, Ph.D.

One of the rapidly advancing areas in the treatment of chronic pain is the use of implantable neurostimulation devices. The most common of these are spinal cord stimulators. These devices are typically used in patients who have failed to get adequate relief from medications and conservative treatments such as physical therapy and chiropractic care. Patients who have had surgical procedures in the spine without obtaining relief may also be appropriate candidates for these treatments.

What is a spinal cord stimulator?

Spinal cord stimulators (SCS) are devices that typically consist of one or more leads with multiple electrodes. These leads are placed in the spine along the cord of nerves that transmits pain signals to the brain. These leads connect to a battery that generates electrical pulses in the leads. These electrical pulses are calibrated to disrupt pain signals coming from a particular body region, such as the lower back and legs. Patients with a spinal cord stimulator will feel a mild tingling sensation in place of the pain they normally feel.

Spinal cord stimulator trial systems

Before permanently implanting a spinal cord stimulator, patients will spend several days with a trial system. This system functions much like the permanent spinal cord stimulator system, but only the leads are implanted. The leads run through the patient’s incision site to an external stimulating system. Trying this system allows the patient to find out if the spinal cord stimulator will provide them with pain relief using a temporary system that can be easily removed at the end of the trial. This trial typically lasts about five days and then the trial system is removed. If the patient receives good pain relief, they can have a permanent spinal cord stimulator system implanted.

St. Jude Medical Invisible Trial System

St. Jude Medical is a leader in developing spinal cord stimulator systems. They recently developed the Invisible trial system. Unlike the current trial systems which have a cable connecting the lead to the external stimulator, this system has the lead connected to a Bluetooth device at the incision site. This Bluetooth device wirelessly connects to a controller that the patient can use to turn the stimulation on and off and make other adjustments. This new trial system is being studied and is not yet commercially available.

Invisible Trial System Study

We will be working with St. Jude Medical this spring to test this new system to see if patients find it more convenient than the current trial systems. Eligible patients who are getting a spinal cord stimulator trial can enroll in this study. They would complete the normal trial, except that they would use the current trial system for the first few days before switching to the Invisible trial system for the final few days of the study. They would provide feedback about each system.

If you are interested in getting a spinal cord stimulator, you can speak with your pain management providers. For additional information about this study you can contact me directly at TedS@arizonapain.com.

Ted Swing has more than ten years of research experience and four years of teaching experience in psychology, has published in top psychology and medical journals, and has presented his research at major conferences. He received his Ph.D. in Social Psychology from Iowa State University and has been the Research Director at Arizona Pain since May 2012.

Clinical Trials for Back Pain, Leg Pain, Nerve Injury Pain

By Ted Swing, Ph.D.

We view clinical research as a critical tool in advancing the practice of pain medicine. Through these studies, we work with outside sponsors to test the latest treatments for pain in order to demonstrate their safety and efficacy. New types of treatments usually require supporting evidence from multiple studies before they can gain FDA approval for widespread use.

Seikagaku Herniated Disc Study

Low back pain is by far the most common form of chronic pain. For many patients, they experience pain in the low back that shoots down into one or both legs, sometimes accompanied by numbness. This can be caused by a herniation or bulging of one of one of the discs that separate the vertebral bones of the spine. When a disc bulges outward, it can put increased pressure on the nerve roots that run through the spine in the lower back and cause pain that travels along that nerve. In approximately 90% of cases, this type of pain (called radicular pain or lumbar radiculitis) can be relieved over time with conservative care, such as chiropractic care or physical therapy, medications or epidural steroid injections. If the pain remains at a high level, even after trying these treatments, patients may undergo surgery that removes part of the disc to relieve pressure on the nerve root.

For decades, researchers have been looking for less invasive alternatives to surgery. One promising alternative is a new drug that can be injected into the disc and cause the herniation to shrink inwards, permanently relieving pressure on the nerve root. Several studies in the U.S., Japan and Sweden have shown this treatment to be safe, with promising results for relieving pain. We are now testing this treatment in a phase III study (the last one required before potential FDA approval). Patients who have had moderate to severe low back pain that radiates into one or both legs for less than one year may be eligible for this study. In order to be eligible, patients must have not gotten adequate relief from several forms of conservative care but not yet had any surgery on their lumbar spine. Of those who are eligible and enroll, 75% receive the study drug and 25% receive a control injection.

St. Jude SENSE Study

Some patients with low back and leg pain continue to experience pain even after surgical interventions. These patients may be candidates for a type of implanted device called a spinal cord stimulator (SCS). SCS devices are implanted along the spine and deliver electrical stimulation to the spinal nerves that replaces pain with non-painful tingling sensation. These devices have been used successfully for years in treating pain both to the back and other areas, such as the legs. Though most patients get substantial pain relief from SCS devices, pain in certain areas has proven more difficult to cover for some patients.

St. Jude has developed a new type of SCS device that can also include one or more leads that extend out into the lower back to provide peripheral field stimulation. We are currently testing this device compared to the current device to see if it proves more effective for patients who have had back surgery and continue to experience moderate to severe low back and leg pain. Patients who enroll in this study will be randomly assigned to receive one of two types of devices — either the current SCS or the SCS/peripheral nerve field stimulation device.

Pfizer Lyrica Study

Injuries to the body, such as motor vehicle accidents, falls, crushing or burns, as well as surgical procedures, typically cause pain. In most cases, as the body heals the pain goes away. For some individuals, the injury also affects the nerves themselves, resulting in chronic pain that remains even after the person has otherwise healed. This pain is often distinguished by the area affected, which typically follows the path of a particular nerve branch. For example, a knee injury might cause lasting pain along the saphenous nerve which covers part of the leg.

Certain medications have been found to relieve such nerve pain. For example, pregabalin (Lyrica®) has proven effective for treating forms of nerve pain such as diabetic neuropathy. To date, it has not been studied specifically for the type of post-traumatic nerve pain described here. We are recruiting patients for a study of this type of nerve pain. Those who have chronic peripheral nerve pain (not affecting the spine or head) due to an injury or surgery may be eligible to enroll. Patients will be randomly assigned to receive either pregabalin or placebo for several months as their pain is assessed.
If you are interested in learning more about any of these studies, you can speak with your pain management providers or contact me directly at Teds@arizonapain.com.

Ted Swing has more than nine years of research experience and four years of teaching experience in psychology, has published in top psychology and medical journals, and has presented his research at major conferences. He received his Ph.D. in Social Psychology from Iowa State University and has been the Research Director at Arizona Pain since May 2012.