With VNS, additional strides in controlling epilepsy

Dr. Ashesh Mehta during vagus nerve surgery in July. A new generation of implants do much more than deliver preprogrammed electrical pulses.

By GREGORY ZELLER // Dr. Ashesh Mehta, head of North Shore-LIJ’s epilepsy care center, performed two surgeries on July 24, one fairly routine, one a bit less so. For now, anyway.

Both involved VNS, or electrical stimulation of the vagus nerves, the long bundle of fibers connecting the brain and abdomen. The first replaced the battery in an existing vagus-stimulation device implanted in a 30-year-old woman. As surgical procedures go, pure housekeeping, Mehta noted.

“After a few years, those batteries need to be replaced,” he said, and the patient has been “doing great” since the operation.

Patient two was a 17-year-old male getting a more advanced stimulator for the first time.

This roughly one-hour procedure involved two small incisions on the left side of his neck and one in the left chest, below the collarbone. An AspireSR, the latest generation of vagus stimulators by Texas biotech manufacturer Cyberonics, was placed inside his chest and connected to the vagus nerve near the neck by a thin, flexible wire.

Although the procedure marked the first time an AspireSR has been implanted on Long Island, Cyberonics has been producing vagus stimulators for years. Its latest generation, however, takes the devices into the “smart” realm, Mehta noted: Instead of simply sending out preprogrammed pulses to stimulate the nerves, the AspireSR interacts with the host body on a much deeper level.

“It’s actually sensing information from the body and changing the stimulation accordingly,” the doctor said. “This really represents a new class of device that directly measures brain activity and then stimulates nerves or brain cells to modulate what’s going on.”

This may prove a critical advancement for nerve-stimulation therapies, which researchers say can deliver potentially enormous health benefits. Measuring and altering brain activity from the inside with a device that can react in real time is especially important regarding the mitigation of seizures, since the brain – in the moments before a seizure – often sends a signal that speeds up the heart.

Intercepting that signal could be a major preventative step, “a back door to neural modulation, based on recording something the brain is projecting,” Mehta said.

“Seizures often occur when the brain cells all fire at once,” he said. “The goal is to get some input into the brain to make fewer brain cells fire at the same time. We know that by stimulating nerves in the head and neck, we can reduce the chances that all these brain cells will fire at once.”

The 17-year-old patient has been suffering seizures since he was a baby, including fairly intense episodes since the age of 10. His anti-seizure medications lost their effectiveness over time, Mehta noted, and while VNS emerged as a viable alternative, it’s certainly no instant fix, nor is it expected to “cure” the young man.

When Aspire stimulators, about the size of a matchbook, are implanted, doctors have to wait several weeks before they can even turn them on, giving the patient’s body time to adjust to a foreign object.

After that, it’s another three to six months to reach what the doctor called “peak efficacy.” In the Bay Shore patient’s case, there was no tickling in his throat or other signs of irritation, so roughly 14 days after the implant procedure, his doctors turned on the AspireSR and neurologists set the first electrical dose.

With the stimulator now sending tiny pulses into his vagus nerves, doctors “will ramp up the stimulation” over time, according to Mehta, who noted the goal is not to eliminate the boy’s seizures but to “improve seizure control.”

“Right now, he’s having seizures unpredictably about once or twice a month,” he said. “We’re hoping to reduce that by half or more.”

The results of the procedure will likely find their way into a study Mehta is performing with contributions from Dr. Kevin Tracey and his team at the Feinstein Institute for Medical Research, where vagus nerve stimulation was born. The study takes a close look at VNS’s effects on the immune system, including inflammatory responses.

While Mehta has no official relationship to the Feinstein CEO, Tracey’s work is another potential key to unlocking many nerve-stimulation-based health benefits, Mehta said.

For now, VNS is FDA-approved only as a treatment for epilepsy and depression. Advances like the next-level AspireSR, combined with new breakthroughs by researchers like Tracey and new studies chronicling them, could open the VNS door to arthritis, congestive heart failure and a host of indications in between.

“This may work both ways,” Mehta said. “It may not only work going up to the brain, but it may also work downstream, filtering down to the immune system. We just don’t know yet.”