University Medical Center neurosurgeons implanted a 26-year-old woman with an experimental epilepsy treatment device Friday, the first such implant in Arizona.

In the hour-long operation, surgeons Allan Hamilton and William Smith implanted the pocketwatch-sized device in the upper left chest of patient Deanna Dunham of Gilbert, Ariz.

"The operation went very smoothly," Hamilton said.

The device, called the NeuroCybernetic Prosthesis System, is similar to a pacemaker. It delivers battery-powered electrical stimulation to the patient's vagus nerve to combat epileptic seizures. The nerve is used as a pathway to the brain because it is ea sily accessible through the chest, said Dr. David Labiner, director of the Arizona comprehensive epilepsy program.

"Nerves are like wires; you can send electricity either way on them," he said. "We're just using the nerve to send something up to the brain."

Dunham said she was feeling fine on Monday.

Although the device was implanted on Friday, it will be activated Feb. 2 to allow Dunham time to recover from the operation.

"I'm looking forward to it," said Dunham.

The device's effectiveness will not be known until it is activated.

Epilepsy, characterized by abnormal firing of a person's neurons, causes seizures which range from brief staring spells to a loss of consciousness, said Labiner. The "daydream" condition is known as "petit mal" seizure, while the unconscious and often spa smodic state is called "grand mal."

"Unlike a light switch, neurons are at different levels of energy," he said. "Seizures are just an abnormal amount of electric discharges."

Once operating, the device will stimulate the vagus nerve to head off seizures, Labiner said. Patients can also trigger the device if they have a warning sign known as an "aura," a vague feeling of disorientation that some epileptics feel just before a s eizure.

Disease, head injuries and a possible hereditary link can cause epilepsy, but in many cases doctors have little idea why they occur at all, Labiner said.

Treatments for epilepsy include medication and brain surgery, but these sometimes include negative side effects and varying ranges of success, he said.

The University of Arizona Department of Neurology is one of two Southwest institutions participating in the Food and Drug Administration's approved study to determine the effectiveness of the device, Labiner said.

Two hundred patients across the country will be implanted with the device in the study, including 10 at UMC.