Experts agree the biggest current market for neurotechnology is treatment of chronic pain, which affects more than 90 million people in the U.S. alone and costs nearly $80 million a year in lost work time, according to the National Institutes of Health. To get relief, many patients resort to powerful narcotic and analgesic drugs. In one recent year, notes the Dept. of Health and Human Services, overdoses of such drugs accounted for more than 108,000 emergency room visits. Back pain — or the agony from failed back surgery — are the biggest culprits.

Companies like medical giant Medtronic and ANS, which became part of St. Jude Medical in late 2005, have led the way in developing spinal cord stimulation systems (SCS) that act as “pacemakers for pain.” The implantable devices interrupt the pain signals' pathways to the brain by delivering low-intensity electrical impulses to nerve fibers along the spinal cord. SCS therapy has been shown to reduce pain by 50 percent or more.

The ANS flagship product for chronic pain is the EON™ system, approved by the FDA in June 2005. Its implanted pulse generator (IPG), featuring a rechargeable lithium-ion battery, is designed to last a minimum of seven years at high power settings. EON can also power up to 16 independent electrodes, which gives clinicians more programming options to better manage the patient's pain.

The key differentiator in the EON is the IPG's custom microchip and enhanced software, which deliver more speed, power and efficiency versus previous systems, according to Tom Hickman, VP of product management for ANS. The IPG is linked through RF communications to a Rapid Programmer platform, the system's control unit. This device allows for real-time programming adjustments for patients suffering from complex pain patterns, such as a combination of back and leg pain.

Hickman adds, leads and electrodes also play a key role in neurotech applications and a great deal of intellectual property surrounding these devices involves the number, shape and precise placement of leads and electrodes. “Leads are where the rubber meets the road, in terms of delivering the desired stimulus,” says Hickman. “No amount of programming will overcome poorly placed leads.”

With more than 30,000 patients now getting pain relief through its SCS systems, ANS is exploring other applications. For example, the company is testing its Genesis neurostimulation system in clinical research as a therapy for helping patients with chronic migraine. In this application, the IPG, implanted in the buttock or chest area, sends electrical impulses to the occipital nerves in the back of the head.

Beyond chronic pain, engineers and researchers are looking to neurostimulators as a tool for treating brain disorders, such as Parkinson's disease and to help patients control epilepsy and restore function in the aftermath of strokes.

Medtronic led the way in Deep Brain Stimulation (DBS) with its Activa Therapy, approved by the FDA in 1997, to control movement disorders associated with Parkinson's and essential tremor. In this application, the electrode array is placed in the thalamus to interrupt wayward brain signals that cause the shaking and abrupt movements that plague these patients.

Some 30,000 patients worldwide have received this therapy since Medtronic commercially launched the Activa device. In most of these cases, drugs had either failed to provide relief from the symptoms or caused serious side effects. Studies also found the device is more effective in controlling movement disorders than a pallidotomy, an ablative surgical procedure that involves removal of brain tissue. Unlike brain surgery, which is not reversible, Activa can be removed if clinicians opt for other treatments.

Among Medtronic's latest advances in the Activa system is the Kinetra® neurostimulator, approved by the FDA in 2004. This device accommodates two DBS leads carrying electrical impulses to both the left and right sides of brain. Before the Kinetra, treatment of Bilateral symptoms caused by Parkinson's disease required separate implants of two neurostimulators.

Lynn Otten, the 1999 Design News Engineer of the Year and one of the key Medtronic engineers on the Activa development team, points out the benefits of DBS are by no means limited to patients with movement disorders. “It also holds promise as a treatment for medically refractory epilepsy, as well as severe Depression and obsessive compulsive behavior,” says Otten.