ST. LOUIS PARK, Minn. (AP) _ Don Falk stretched his right arm over his head, past the faint marks where a surgeon sank two wires deep in his brain, to show how uncontrollable tremors in his hand used to slap him awake in the morning.
It was just one of many difficulties he suffered as his Parkinson's disease advanced. Falk had trouble shaving and walking, and his medications caused his head to twitch awkwardly, making him self-conscious in church.
``It's the day-to-day living that is so hard with Parkinson's,'' he said.
In May, Falk, 52, started to get better with the help of an emerging class of implantable medical devices called neuromodulators _ tiny machines that stimulate the central nervous system to treat a host of disorders. Analysts say they could be the next big thing for some of the market's hottest medical technology companies.
Of course, the same hurdles that have stood in the way of other medical technologies will have to be overcome, including getting government approvals, securing adequate insurance reimbursements and persuading busy doctors to learn to use the devices.
The deep brain stimulator silently pulsing away deep in Falk's head is made by Fridley-based Medtronic Inc., a multibillion dollar medical device company and the leader in the more than $1 billion market for neuromodulators.
Medtronic has the only deep brain stimulator on the market, but St. Paul-based St. Jude Medical Inc. is in clinical trials of its own version through its newly acquired subsidiary Advanced Neuromodulation Systems Inc. of Plano, Texas, which already sells spinal implants to treat chronic pain.
``I can tell you eight years ago, neuromodulation was not on the tip of anybody's tongue, but today it is reaching critical mass and it's gaining momentum and people are starting to imagine what is possible,'' said Chris Chavez, president of St. Jude Medical's ANS division.
Cyberonics Inc. of Houston is the smallest player, with a device to treat epilepsy by shocking a nerve in the neck, and Boston Scientific bought into the market in 2004 by acquiring Sylmar, Calif.-based Advanced Bionics Corp., a maker of robotic inner ears.
The acquisitions show even some of the nation's hottest medical technology companies see neuromodulation as part of their future, said Jan Wald, an analyst for A.G. Edwards.
``They were looking for growth and they found it in neuromodulation,'' Wald said.
Medtronic, St. Jude Medical and Boston Scientific don't break out sales figures for their neuromodulation devices.
But ANS quarterly revenue rose 26 percent to $39.3 million during its last quarter before St. Jude bought it in November for $1.4 billion. And Cyberonics Inc. reported sales grew 19 percent to $31.3 million for the quarter ended Jan. 27, though the company reported an overall loss on heavy spending to prepare marketing of a newly approved neuromodulation therapy for drug-resistant chronic depression.
Neuromodulators are technological cousins of implantable heart defibrillators, a $5.5 billion market that's growing at nearly 20 percent a year.
The devices do have some hurdles. While they've been shown to be safe and effective at treating some disorders, they're generally recommended only after drugs and other less invasive treatments fail.
The surgical procedure can be complex, and the devices themselves are expensive, about $50,000 for the deep brain stimulator, less for other devices in the class. And that doesn't include the costs of surgery.
The results are impressive, but ``it's not a big moneymaker,'' said Dr. Richard Veyna, Falk's neurosurgeon at Methodist Hospital in this Minneapolis suburb. Not enough doctors know about the technology, and at current insurance reimbursement rates simpler procedures are more profitable, Veyna said.
Perhaps surprisingly, the risks of brain surgery rarely dissuade patients, maybe because they are tired of living with Parkinson's symptoms and have seen other treatments fail, he said.
Falk said he didn't hesitate about brain surgery. ``My tremor was so bad I just wanted it done,'' he said. His adult children didn't think twice either: ``They did not like me just sitting there, shaking and stuff.''
Falk touts his procedure to other Parkinson's patients, telling them that his medication has been cut by two-thirds and his insurance covered the procedure.
Competition, higher volume and technological advances drove down the costs of implantable cardiac devices, and could do the same for the neuromodulators. Only a small number of people who might benefit from the devices _ people who suffer from Parkinson's, tremors, epilepsy, chronic depression or chronic pain _ are now getting them, Wald said.
``Neurostimulation to me, in fact the whole neurological space, is what cardiology was 10 years ago,'' Wald said. ``The opportunity is just vast.''
Nearly all neuromodulation systems have the same general parts: Pulse generators, wires that touch nerves and implanted batteries, which must be replaced every few years. The most common versions are implanted in the spine, not the brain.
Dr. Todd Sitzman, an anesthesiologist in Hattiesburg, Miss., has used them in hundreds of patients with chronic pain over the last decade.
``Does it work from the patient's perspective? Without question,'' said Sitzman, who sits on the National Pain Foundation's board of directors. ``It is a therapy that gives them some relief and some semblance of a life.''
Companies are already pushing to develop new applications for the devices. They see potential uses in treating diseases including depression, obsessive-compulsive disorder, erectile dysfunction, traumatic brain injuries, obesity, angina, incontinence and ringing in the ears.
St. Jude's Chavez said those possibilities, along with the aging populations in the United States, Japan and Europe, made it likely that any financial hurdles for the devices would only be temporary.
Falk now has two bumps where his forehead meets his hairline, evidence of the plastic plugs that sealed dime-sized holes in his skull. The surgery was unpleasant, he said, but his medications have been sharply reduced and the worst of the tremors are gone.
Everything is simpler now. The Coon Rapids man can use a computer mouse because his hand doesn't shake like it used to.
``Just getting out of bed is easier,'' he said.