Treating chronic pain in patients who have had failed back surgery has always been a dicey and, many times, unsuccessful venture. With as many as 20 million people suffering from this type of pain as well as pain of the trunk or limbs, St. Jude Medical (St. Paul, Minnesota) has miniaturized its Eon neurostimulation device to meet their needs.

Both FDA and European CE-mark approvals have been granted for Eon Mini, a long-lasting rechargeable neurostimulator to treat chronic pain of the trunk or limbs, and pain in people whose back surgeries failed. It is based on the original Eon, which has been on the market for three years.

Slightly larger than the circumference of a U.S. silver dollar, the Eon Mini neurostimulator has a 10 mm profile and weighs about one ounce. The small size allows for a smaller incision, which gives physicians increased flexibility in selecting the implant location and is intended to make the site less visible and more comfortable for patients.

"The beauty of neurostimulation therapy for chronic pain is that physicians can do a trial of the device that is minimally invasive and reversible to determine if it will work for the patient," Tom Hickman, vice president of product management for St. Jude's Advanced Neuromodulation Systems division, told MDD.

Trial runs can last three to 10 days. Physicians simply place leads and use the device externally to find out if it's going to work before implantation. With a price tag of $15,000 to $25,000, a trial makes economic sense. Hickman said the Eon Mini is reimbursed by Medicare and most insurers.

The neurostimulator is expected to help control pain, but "It's not a cure. It's used in combination with other treatments such as physical therapy, and allows patient to have a better quality of life," Hickman said.

He said it's the smallest and has the longest-lasting battery life of any rechargeable spinal cord stimulation (SCS) device in its class.

"Eon Mini is less than half the size of original Eon. One of the key advancements is continued evolution of neurodynamics technology," Hickman said. "That takes into consideration greater efficiencies in delivering therapy and how it's used in the device itself."

Device size is an important consideration, offering patients greater comfort, and making it ideal for those whose body type requires a small device.

Eon Mini is currently the only small rechargeable neurostimulator to receive a 10-year battery longevity approval by the FDA. For patients, that means it should provide sustainable therapy and maintain a reasonable recharge interval for 10 years of use at high settings. Its battery longevity also may mean that patients require fewer battery replacement surgeries.

Eon Mini allows patients the ability to recharge the device's battery anywhere or anytime because the charging system is fully portable. Enhanced microchip and software, called NeuroDynamix technology, continuously selects the most efficient power management mode, preserving the battery's capacity to deliver therapy. Constant current circuitry automatically adjusts power output to deliver consistent therapy over time.

A 16-contact header that is compatible with all St. Jude Medical SCS leads, gives physicians more control in designing the system for optimal pain relief.

A spinal cord stimulation system, which operates like a pacemaker, includes a neurostimulator or generator, one or more thin wires with several electrodes or contacts that carry mild electrical pulses from the device to specific segments of the spinal cord, a patient controller, and the programmer — a device that enables the doctor or clinician to adjust and fine-tune the stimulation programs.