He gave Mr. Carson a tremor -- but behind the scenes, Julian Fellowes was the one shaking.

The "Downton Abbey" creator recently opened up about how he's overcoming a supposedly "incurable" condition that made everyday tasks nearly impossible, thanks to a "terrifying" yet "revolutionary" procedure.

"You're kept awake the whole time," Fellowes, 76, said in a new video with Insightec, which documents his journey to treat a little-known neurological disorder that affects an estimated 1 in 5 US adults over the age of 65.

It's called an essential tremor, a nervous system disorder that causes uncontrollable, rhythmic shaking. It can strike almost any part of the body but most often hits the hands, arms, head and voice, according to the Mayo Clinic.

Often confused with Parkinson's disease, essential tremors flare up during movement -- like lifting a cup or writing -- unlike Parkinson's shakes, which tend to be most prevalent when the body is at rest.

Anyone can develop the movement disorder, but it's most common in older adults.

"It started for me around my mid-60s," Fellowes said. "At the beginning I was in denial and I sort of said, 'Oh, wonder what's the matter with me today.' But gradually I realized it was a condition."

The main symptom is shaking, usually in the hands. The trembling tends to worsen with movement, but things like stress, fatigue and caffeine can also exacerbate it.

As it advances, the tremor can take a major toll on your quality of life -- making it tough to eat, drink or even get dressed independently.

"Doing up buttons, fastening a tie -- everything became a labor. My cufflinks would go flying off," Fellowes said in an interview with The Times. "It is very, very depressing and upsetting."

Experts aren't exactly sure, but research suggests it's linked to changes in specific areas of the brain, according to the Cleveland Clinic.

What is known is that essential tremor often runs in families, with about half of all cases inherited. Currently, there's no known way to prevent the condition.

When Fellowes was first diagnosed, a specialist told him the condition was "incurable." Over the last decade, however, new treatments have emerged.

Options include medication, physical therapy, assistive devices or deep brain stimulation. But the "Gilded Age" creator chose a treatment that sounds straight out of a science fiction movie.

In May, he underwent a noninvasive procedure that fires MRI-guided focused ultrasound beams into the brain, targeting and destroying the tremor-producing tissue without harming surrounding areas.

"They put this metal crown on to keep your head still, which is quite unpleasant," he told The Times. The 76-year-old was conscious during the entire operation so doctors could monitor his responses.

It was an almost instant success.

In a video, Fellowes can be seen effortlessly drawing spirals on paper -- a dramatic improvement from the shaky spiral he scrawled down before the procedure.

He even managed to drink from a glass.

"That's quite strange, actually, because I haven't trusted myself to do that for some time," he said.

Just a month after the treatment, Fellowes regained his ability to write.

"For me at least, this was worth it and I haven't regretted it for one second," he said.

Fellowes isn't alone. A 2022 study found patients with essential tremor maintained a 73% reduction in shaking severity five years after undergoing a focused ultrasound thalamotomy.

"I've had the treatment and I've, in a sense, cured the tremor in my right hand. And I want people to know that," he said. "I hope that I can be of some small use in getting it known."

'Downton Abbey' creator Julian Fellowes reveals how he cured...