Brain implants for essential tremor calm artist’s hands

Thanks to deep brain stimulation, an artist stricken with a common but lesser known neurological disorder called essential tremor can paint again with a steady hand.

- By Bruce Goldman

You’re an artist. How do you paint a landscape if you can’t draw a straight line? 

Terri Benedix, who specializes in floral paintings along with landscapes and seascapes, couldn’t even raise a cup of coffee to her lips without spilling it, or lift a forkful of peas without sending the vegetables flying.

That changed in an eyeblink after a procedure in which electrodes were implanted in precise locations on each side of her brain, then hooked up to a battery-operated, pacemaker-like device installed in her chest. The hardware was part of an increasingly popular treatment called deep-brain stimulation: rhythmic bursts of electrical pulses to targeted brain regions. 

The pulses disrupt spontaneously generated rhythms in the brain that cause essential tremor, a condition that affects an estimated 2.2% of the American population — about 1 in 25 adults age 40 and older and 1 in 10 adults over 75.

 “It’s the forgotten disease,” said Casey Halpern, MD, associate professor of neurosurgery at the Stanford School of Medicine. “It needs someone like Michael J. Fox to promote awareness, research and treatment.”

Essential tremor is progressive, often beginning with a visible tremor in one hand and gradually affecting muscle groups on both sides of the body. Unlike Parkinson’s disease, it’s not accompanied by cognitive, cardiovascular or other symptoms. The  shaking from essential tremor is visible mainly when people with the condition use their hands.

Essential tremor impairs nerve cells that control movement and restraint and that run from the cerebellum, in the back of the brain, to a structure called the thalamus in the brain’s center. “When those nerve cells die off or begin to malfunction, cells in a portion of the thalamus begin spontaneously firing in rhythmic synchrony,” Halpern said. “That’s what’s thought to cause the tremor.”

By preventing those neurons from defaulting to a spontaneous rhythm, deep-brain stimulation — or DBS — can restore control. First approved in 1991 for essential tremor, DBS is now used for Parkinson’s disease, obsessive-compulsive disorder, epilepsy and some types of dystonia, a movement disorder in which a person’s muscles contract uncontrollably. 

Family history of essential tremor

Halpern surgically implants about 40 DBS devices annually for essential tremor. One of his patients is 58-year-old Benedix. 

A longtime resident of Atascadero, a town about 15 miles from the ocean on California’s Central Coast, Benedix has been an artist since she was a teenager. About seven years ago, her tremor forced her to stop teaching art, which she had been doing her entire adult life. 

“That was a motivating factor,” she said of her decision to undergo the surgery. “That, along with not being able to eat. We have lots of stories about food flying across the room.”

Benedix has a family history of essential tremor, which is often hereditary. In 2013, the shaking started in her right arm. A local neurologist initially put her on a drug to relieve the tremor. It worked fine, until it didn’t. Likewise, a second drug began losing potency as the disease progressed. 

Terri Benedix met with Casey Halpern in January at a follow-up appointment. Her deep-brain stimulation device was implanted in the summer of 2020. 
Steve Fisch

The symptoms spread to both arms, her legs, her neck and even her tongue. The results were messy — and even hazardous. “My shaking got so violent I couldn’t use a knife properly,” she said. “I cut myself several times slicing a cucumber or a tomato.”

Liquid spilled from cups. Food flew off her fork. She had to eat with her hands.

On bad days, she couldn’t fix her hair. When she tried to apply makeup, lines of lipstick or eyeliner would run up or down her cheek.

Her voice grew tremulous.

“It’s not one incident that happens,” Benedix said. “When you put them all together, it becomes overwhelming. It’s like little pebbles in a bucket. By the end of the day, your bucket’s full.”

One time at a salad bar with a friend, she tried to put some peas on her plate. “My hand jerked. Peas went everywhere.” Her friend took care of it.

Avoiding further invitations to eat out, she became a homebody, isolated and dependent. “It finally got to where I couldn’t feed myself,” she said. “I could only drink through a straw.”

Her husband started feeding her. 

She’d stopped painting. She couldn’t draw, sign her name or do paperwork. Her husband helped her fill out medical forms.

Referral to Stanford Health Care neurosurgeon 

In 2019, her neurologist referred her to Halpern at Stanford Health Care. In the course of a few visits, Halpern explained how DBS works. There would be two surgeries: one to implant the electrical leads and another to install the pulse generator, which would be connected to the leads and produce a steady train of electrical pulses. He told Benedix she could expect a better than 70% reduction in tremor severity over the long term — a conservative estimate — although she’d eventually experience some mild return of symptoms.

She decided to proceed. On July 23, 2020, she showed up at Stanford Hospital for surgery.

Terri Benedix with her husband, Dale.
Steve Fisch

The medical team sedated her while Halpern drilled two small openings in her skull, one on each side, to make room for two electrical wires to be threaded through the skull openings to the thalamus in each hemisphere of her brain.

Then, the team brought her back to consciousness so she could help them properly position the electrical leads. Her head was completely immobilized to ensure precise electrode placement. She felt no pain, as the brain has no pain receptors.

Halpern started by using a recording electrode with a microphone attached to it. He zeroed in on the location of tremor-inducing cells by sound. “We listen for the pattern suggestive of the pulsing rhythmic activity that’s responsible for the tremor,” he said. Once he’d found what seemed like the right place, he inserted and positioned the stimulating electrode and asked her to draw a spiral. 

She executed a very recognizable one. Tears flooded her eyes. 

“It was a miracle to see the change,” she said. “Dr. Halpern told me, ‘That’s where we’ll leave the permanent electrode.’ And they put me back to sleep.” 

A machine with a precision arm aided the insertion of the leads at the specified coordinates. Leaving the wires in place, Halpern bandaged up the incision sites. 

In a follow-up procedure a few days later, Halpern connected the extensions to a pulse generator. He made a 2½-inch incision on one side of Benedix’s chest and placed the pulse generator below her collarbone. Using a device to tunnel beneath her skin, he threaded the reserve coils of exposed wire on her head past her ears, down the back of her neck and over her shoulders to her chest, where he connected the wires to the pulse generator.

The two operations took about three hours in all. 

Benedix returned to Stanford Health Care a month later. Movement-disorder specialist Traci Hornbeck, a physician assistant in Stanford’s Department of Neurosurgery who’s been programming DBS devices since 2004, activated the device. Ratcheting up the current in small steps, Hornbeck adjusted the pulse volume to provide maximum tremor inhibition without triggering side effects such as slurred speech, sensory disturbances, involuntary muscle contractions or balance problems.

The effect kicked in right away. Hornbeck estimates that activating the device reduced Benedix’s tremor by 90%.

“It was almost like being in the dark and having a light switched on,” Benedix recalled.

Hornbeck tested Benedix’s ability to draw a straight line and a spiral, sign her name, stretch her arms to the side, apply mascara and bring a cup of water to her mouth. 

“Most patients are skeptical,” Hornbeck said. “Often it’s been years since they’ve tried. They say, ‘I can’t do it!’ I say, ‘Yeah, you can.’” 

Hornbeck should know. “I always tell patients that I’m part of the tremor tribe,” she said. “I have essential tremor myself.”

Excited, Benedix got on her phone and started texting family members. Typing with that tiny keyboard would have been difficult, if not impossible, just minutes earlier.

“In that moment, I knew that everything in my life was going to change,” Benedix said. “And from that moment on, I’ve become more independent every day.”

Hornbeck gave Benedix a battery charger and a remote control. She can regulate the device settings within limits, optimizing separately for her left and right hands.

“It’s just like your TV — if you need your volume turned up, you just do it,” she said.

Benedix doesn’t expect perfection. She understands that her disease will progress. But her current amplitude is set low; there’s plenty of room left to ramp it up.

“I feel like my life has been handed back to me,” she said. “I only wish I’d done this four years sooner.”

About Stanford Medicine

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2023 ISSUE 3

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