Today the U.S. Food and Drug Administration approved the Senza spinal cord stimulation (SCS) system (Senza System) as an aid in the management of chronic intractable pain of the trunk and/or limbs, including pain associated with failed back surgery syndrome, low back pain and leg pain. The Senza System can reduce pain without producing a tingling sensation called paresthesia by providing high frequency stimulation (at 10 KHz) and low stimulation amplitudes.
“The FDA has approved several other totally implanted spinal cord stimulators for pain reduction, but this system is unique because it delivers a high frequency output of 10 kHz that does not cause a tingling sensation—called ‘paresthesia’—in patients,” said William Maisel, M.D., M.P.H., acting director of the Office of Device Evaluation at FDA’s Center for Devices and Radiological Health. “Since some patients don’t like the paresthesia associated with traditional SCS, this device offers another treatment option.”
Back pain is a common disability for many Americans. Acute pain begins suddenly and is usually sharp in quality. Acute pain might be mild and last just a moment, or it might be severe and may last three to six months. In most cases, acute pain disappears when the underlying cause of pain has been treated or has healed. Unrelieved acute pain, however, might lead to chronic pain. Chronic pain is pain that lasts more than 12 weeks and may persist for years. Chronic pain might have originated with an initial trauma/injury or infection, or there might be an ongoing cause of pain. However, some people suffer chronic pain in the absence of any past injury or evidence of body damage.
Before receiving treatment with the Senza System, patients participate in a one- to two-week simulation using an implanted trial lead and a model of the stimulus generator that is worn outside the body. Once the doctor determines the stimulation works well based on the patient’s reporting of symptoms, the system is implanted via a minimally invasive surgical procedure. The system delivers electrical stimulation to the thoracolumbar area of the spinal cord (in the region of the mid to lower back) via leads implanted through a small incision in the patient’s back. The lead is connected to a rechargeable, implantable pulse generator that is implanted in the patient’s upper buttocks region or abdomen. A clinician initially programs the device, and patients can use a remote to control the pulse generator within the output ranges programmed by the clinician.
FDA’s review of safety and effectiveness included data from a clinical study. During the study, 198 subjects with chronic intractable pain of the trunk and/or limbs were randomized to either the Senza System test group or a control group. The control group was made up of 97 subjects treated with another FDA-approved device that delivers stimulation in the two to 1,200 Hz frequency range that produced paresthesia.
Seventy-five percent of subjects treated with the Senza System achieved a 50 percent reduction in pain from baseline at three months, which was the primary target of the study, and an approximately 55 percent reduction at 12 months.
There were no stimulation-related neurological deficits, such as weakness in the limbs or tremors, observed for either treatment group. The most common adverse events associated with the Senza System included pain at the implant site and dislocation of the device lead under the skin.
The FDA also approved the Senza System for stimulation parameters below 10 KHz. For stimulation parameters, similar to those used in the control group and other traditional SCS systems, paresthesia is required.
The Senza System is manufactured by Nevro Corp., based in Menlo, California.
Posted on the FDA website on 8 May 2015