FDA: 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.
The
FDA, an agency within the U.S. Department of Health and Human Services,
protects the public health by assuring the safety, effectiveness, and
security of human and veterinary drugs, vaccines and other biological
products for human use, and medical devices. The agency also is
responsible for the safety and security of our nation’s food supply,
cosmetics, dietary supplements, products that give off electronic
radiation, and for regulating tobacco products.