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FDA Approves Spinal Cord Stimulation System That Treats Pain Without Causing Paresthesia

Device consists of implanted leads and external stimulus generator

The FDA has approved the Senza spinal cord stimulation (SCS) system (Nevro Corp.) 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 paresthesia by providing high-frequency stimulation (at 10 KHz) and low-stimulation amplitudes.

Back pain is a common disability for many Americans. Acute pain begins suddenly and is usually sharp in nature. Acute pain might be mild and last just a moment, or it might be severe and may last 3 to 6 months. In most cases, the 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 experience chronic pain in the absence of a past injury or evidence of body damage.

Before receiving treatment with the Senza system, the patients participate in a 1- to 2-week simulation phase using an implanted trial lead and a model of the stimulus generator, which is worn outside the body. Once the doctor determines that 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 leads are connected to a rechargeable pulse generator that is implanted in the patient’s upper buttocks 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.

The FDA’s review of the safety and effectiveness of the Senza system included data from a pivotal clinical study in which 198 subjects with chronic intractable pain of the trunk and/or limbs were randomly assigned to either the Senza system test group or a control group. The control group consisted of 97 subjects who were treated with another FDA-approved device that delivered stimulation in the 2- to 1,200-Hz frequency range, which produced paresthesia.

Of the patients treated with the Senza system, 75% achieved a 50% reduction in pain from baseline at 3 months (the study’s primary endpoint) and approximately a 55% reduction at 12 months.

No stimulation-related neurological deficits, such as weakness in the limbs or tremors, were 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 leads 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 in other traditional SCS systems, paresthesia is required.

Source: FDA; May 8, 2015.

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