By Ted Swing, Ph.D.
The loss of a leg due to an accident or other cause can pose a number of challenges, from the immediate pain and walking again with prosthesis. Such injuries can also cause severe chronic pain, potentially lasting for years. These patients may have their chronic pain managed with medications, injections, or ablations of the affected nerves, which are often effective in reducing this pain. We are taking part in a new study for those patients with a leg amputation who continue to have severe chronic pain despite such treatments. This study may offer them another option for pain relief.
We believe that neurostimulation devices are one of the most promising frontiers in chronic pain management, as they offer the potential for significant pain relief, often with fewer risks and side effects than many medications and surgical procedures. The most widely used of these devices are spinal cord stimulators. These devices deliver pulses of mild electrical stimulation to the spinal cord to disrupt and replace the pain in an affected area. Neuros Medical has developed a new type of neurostimulation device – the Altius® system – and they are testing it with patients who have lost a lower limb.
The Altius is different from most neurostimulation devices in several ways. Rather than placing the lead that delivers stimulation in the spine, the Altius system uses a cuff electrode that is implanted around the sciatic nerve. This is a large nerve running into the thigh, branching off to gather sensations (including pain) from the whole leg. The Altius system also delivers stimulation much faster than most neurostimulation devices – thousands of times every second. This rate of stimulation is so rapid that patients don’t even feel the mild tingling feeling that normally accompanies stimulation, yet some early studies have found it to be effective in relieving pain. In fact, this relief seems to last for hours even after stimulation is turned off.
As we begin this study, we’ll be looking for lower limb amputees who have had severe chronic pain in that limb for at least 12 months. Patients must be at least 21 years old and willing to complete several follow up visits for at least one year. Patients who qualify and enroll in the study will have the Altius system implanted. For the first three months after this device is activated, patients will be randomized: half will receive a therapeutic level of stimulation expected to relieve their pain and half will receive a control level of stimulation for comparison. Patients will not know which type of stimulation they are receiving. This period is to evaluate the efficacy of the treatment. However, after the 3 month follow up visit, all patients will receive a therapeutic level of stimulation and may continue using the device after the study.