Medications helped but didn't control his seizures.
In 1990, he attempted suicide by taking an overdose of one of his drugs. He says he hit "rock bottom." He was "sick and tired" of the way his life was.
Changes in medications prescribed by Dr. Mehrullah Khan, Davis' Hagerstown neurologist since 1994, reduced his seizures to about 12 per week.
Last summer, Khan told Davis about another treatment possibility - a device called a "pacemaker for the brain" by manufacturer Cyberonics, a Houston-based corporation.
The NeuroCybernetic Prosthesis (NCP) System, which received U.S. Food and Drug Administration approval in 1997, consists of a battery-powered generator that is surgically implanted in the chest under the skin. The "same-day" surgery is performed under general anesthesia. A second incision is made in the neck so that coils at the end of a wire from the generator can be wrapped around the vagus nerve in the neck to deliver mild electrical stimulation.
The vagus nerve is the leading provider of information from the heart, lungs, blood vessels and gastrointestinal tract to the brain.
A couple of weeks after the system is implanted, the patient visits his neurologist and the generator in his chest is programmed to send precisely timed and measured electrical pulses to the vagus nerve. The NCP system conditions the brain to react to interruptions of normal brain functions caused by epilepsy, according to Cyberonics. The device can decrease or eliminate seizures.
Vagus nerve stimulation is not for everyone. Medications control seizures for 80 percent of people with epilepsy, Khan says. Some of those whose seizures are not controlled by drugs may qualify for brain surgery.
The pros and cons
Davis was skeptical and thoroughly researched the option. But he worried about long-term side effects of the medications he was taking - five or six pills five times a day.
Because of this, he had the device implanted by a neurosurgeon at Frederick Memorial Hospital in Frederick, Md., on June 8. Khan programmed Davis' device a couple of weeks later.
"It's one of the best things that ever happened," Davis says.
He's had only 12 seizures - none of them "full-blown" - since his implant was activated. Because Davis experiences an aura - warning signs - before a seizure begins, he is able to use the strong magnet that comes with his device. When he senses a seizure starting, he "swipes" the magnet across his chest to give the generator an additional dose of stimulation to prevent or abort the seizure.
Jim Hilton feels no warning when he has seizures. The 66-year-old Maugansville resident had his first seizure at age 16. Medications controlled them for more than 20 years, but they started again.
Hilton has "petit mal" seizures - staring into space, lasting for about 20 seconds, says Doris Hilton, his wife. He doesn't feel them coming, and he isn't aware of them as they happen.
He was alone when he fell and broke his shoulder two years ago. He assumes he was having a seizure.
"We decided something had to be done," Doris Hilton says.
Khan told the Hiltons about vagus nerve stimulation. Jim Hilton didn't hesitate. He had his device implanted last Sept. 19.
Although the Hiltons say their expectations for the device may have been a bit unrealistic, they are pleased and prepared to give it more time to become more effective. Jim Hilton experiences one of the therapy's possible side effects - a change in his voice, a hoarseness - when the device is stimulating the vagus nerve. The stimulation can be temporarily stopped by holding or taping the magnet over the device.
Jim Hilton and Davis still take medications, but believe that the therapy has helped them. Doris Hilton calls it a "godsend" and says it has given her husband a better quality of life.
Vagus nerve stimulation is not inexpensive, but most insurance covers the $10,000 cost.
Research is being conducted to test VNS as a possible treatment for depression, obesity and Alzheimer's disease, according to Cyberonics.