At Mayo, brain device offers hope for toughest epilepsy cases

After nine years of epileptic seizures and no success stopping them, Sheri Finstad was ready to try an experiment.

In October, she came to Rochester, where Mayo Clinic doctors implanted a device in her brain designed to deliver mild electrical pulses and record the brain's reaction.

It's a stimulation therapy used typically to treat Parkinson's disease and other neurological disorders. Finstad, a 32-year-old social worker from Fargo, became one of two patients to try it for epileptic seizures after federal regulators OK'd an exemption.

Since the surgery, she's had dizziness and headaches — but just one seizure.

Finstad's therapy is still in its infancy and will need years of clinical studies and FDA approval for any broader use. But her case is helping doctors learn more about how the brain reacts to epilepsy, a condition affecting some 60,000 people in Minnesota and nearly 3 million in the United States.

"We can see exactly what our stimulation does to the ongoing activity in the brain," said Finstad's neurologist, Dr. Matt Stead. "That will allow us ... hopefully to understand better what patterns and types of stimulation are most likely to suppress their propensity toward seizures."

Inside Finstad's brain, electrodes are connected to wires that go down the side of her neck to two stimulators, similar to a pacemaker. Each one is about the size of a small deck of cards. Doctors implanted them just below her collarbones. Inside each device, there's a battery that supplies energy and circuits that provide stimulation and sensing.

The Food and Drug Administration approved a similar device in 2013, the RNS System, made by California-based NeuroPace, but Stead says Finstad's system, made by Twin Cities medical device maker Medtronic, lets doctors record the brain's activity while the stimulation is occurring.

The stimulation is constant, sending low frequency signals to Finstad's brain. She can't tell the device is on.

Pacemakers have had the capability to sense cardiac signals for several decades. But it's been harder to replicate that in the brain, said Tim Denison, a senior engineering director at Medtronic.

Brain signals are "about 1,000 times smaller than what we see off a typical pacemaker," he said. "So it's an real engineering challenge to get the resolution to those signals and especially to try to sense those small signals in the presence of stimulation."

Denison led the team that developed the technology. He wouldn't say how much the device costs, but comparable systems that don't have the ability to record data, range in price from $15,000 to $30,000, according to Mayo's Stead.

Medtronic is providing the devices to Mayo and Finstad for free. Finstad's insurance is covering the cost of the surgery at Mayo. It's unclear what that total will be.

Denison says the device is meant to be a general investigational tool for researchers to explore how stimulation might be used on a variety of diseases, not just epilepsy.

"We started out making sure we can cover our base therapies today of Parkinson's disease, tremor and dystonia," he said. "Researchers, such as those at the Mayo Clinic, are looking at expanding it into other indications, such as epilepsy."

The deep brain stimulation provided some relief for Finstad, who was back at Mayo recently for her first follow-up visit.

The device implant became an option after years of medications and diet changes didn't help ease the seizures.

"I could go weeks without having them, but once I would have seizures, it was unknown how quickly or frequently that they would take place and how impacting that they would be," she said.

Like about a third of people with epilepsy, she didn't respond to traditional treatments. Removing the area of her brain causing the seizures also wasn't an option. With the seizures coming from multiple parts of her brain, surgery might have brought memory loss.

Since the surgery, "I've had some instances where I'll feel really dizzy and then after that I'll end up having a headache afterwards. And then I'll be fine," she told Stead.

"My interpretation is probably those are maybe auras... and technically an aura is the very beginning of a seizure but it sounds like maybe they're getting aborted," Stead told her.

Finstad laughed nervously. "I might start crying," she said. "This could be working."