Safer treatment for depression

Jan 23 2006

Researchers from the University of Pittsburgh, with the help of a team of Pittsburgh high school science teachers, have developed a wireless device that is implanted in the neck to fight depression and epileptic seizures. The U.S. Food and Drug Administration already has approved a wired version of the device, but that one carries risks and several undesirable side effects.

It has been known for several years that stimulating the vagus nerve, which connects the brain to several major organs, can offset drug-resistant epileptic seizures. Last summer, the FDA approved vagus nerve stimulation (VNS) for use to treat severe depression as well. The only current manufacturer of a VNS device is Cyberonics Inc. of Houston. In the company's product, a pulse generator is surgically implanted into the left side of the chest, and a wire extends from the device up through the left side of the neck to wrap around the nerve. Patients must undergo additional surgery to change the battery every three to eight years. The device can be turned off at any time with a magnetic wand.

VNS has few of the side effects of traditional treatments for depression: no sexual dysfunction or memory impairment and minimal sleep disturbance and weight gain, which are often associated with antidepressants or shock therapy. However, there is a risk of infection due to the surgical incisions, and the long wire lead may cause painful adhesions and restricted movement. Additionally, side effects include hoarseness, shortness of breath, and voice alteration, although these are alleviated when the device is turned off.

Last summer, eight teachers from City of Pittsburgh high schools came to Pitt under a National Science Foundation-funded program in which they divided their time between Pitt's Learning Research and Development Center and a research project of their choosing. Four of the teachers chose to work on a device to prevent seizures under the guidance of Marlin Mickle, Nickolas A. DeCecco Professor of Electrical and Computer Engineering at Pitt, director of the University's Radio Frequency Identification Center for Excellence and John A. Swanson Institute for Technical Excellence; Michael Lovell, associate professor of industrial and mechanical engineering and associate dean for research in Pitt's School of Engineering; Robert Sclabassi, professor of neurological surgery, neuroscience, psychiatry, electrical and mechanical engineering, and bioengineering and director of UPMC's Center for Clinical Neurophysiology; and Pitt electrical engineering graduate student Steven Hackworth.

The group hoped to treat seizures by modifying a method for deep-brain stimulation (DBS), which Mickle, Lovell, and Hackworth had developed, that uses radio frequency technology to help treat diseases such as Parkinson's. The major technical challenge they had to overcome was to convert the voltage source required for DBS to the current source required for the seizure treatment.

The solution they developed is the Radio Frequency-powered Neural Stimulator (RFNS). The RFNS is made up of a receiving device implanted under the skin of the neck and a powering device placed near the skin at the same site, under a collar. Because this requires only one surgical incision, rather than the two required by VNS, the risk of infection is reduced. Other advantages of RFNS over the existing VNS system include no invasive tunneling from the shoulder to the neck region and an external battery, which reduces the need for subsequent surgeries and further lowers the risk of infection.

The next step for the researchers is to license the technology to a company, which would then need to obtain FDA approval.