A non-invasive ultrasound therapy can safely improve the symptoms of a common neurological disorder that causes involuntary shaking, a new Canadian study has found.

The study looked at 76 patients with essential tremor, a condition that causes constant shaking and mainly involves the hands and the head. All of the patients in the study had moderate-to-severe tremors that did not respond to medications.

The patients were enrolled in a randomized controlled trial. Some of them received MRI-guided focused ultrasound thalamotomy, a scalpel-free brain surgery that involves destroying small parts of tissue in the thalamus, which co-ordinates and controls muscle activity. 

Other patients in the group underwent “sham,” or placebo, treatment.

After three months, tremors in patients receiving focused ultrasound therapy improved by 46 per cent, compared with a 0.1 per cent improvement in those receiving sham procedures.

The findings were published Wednesday in the New England Journal of Medicine.

Essential tremor can occur at any age, but is most common in those 40 and older. The condition, sometimes confused with Parkinson’s disease, is usually not life-threatening, but it worsens over time and can be severe. In some cases, patients become unable to feed or dress themselves. 

About one million people in Canada are affected by essential tremor. Most patients are able to control their symptoms with medications, but they do not work for everyone. That’s why ultrasound thalamotomy, recently approved for use in Canada and the U.S., is gaining international attention.

The Sunnybrook Hospital in Toronto is currently the only one offering the treatment in Canada and already has a three-month-long waiting list of patients across the country.   

Dr. Nir Lipsman, the co-author of the study and a neurosurgeon at Sunnybrook Research Institute, told CTV News that the technology “has a significant impact on (patients’) quality of life – without making a hole in the skull or an incision.”

He said the results have been “extremely rewarding” and doctors are “thrilled” for patients who see significant improvements. Among them is Noreen Smith, a 76-year-old former nurse whose tremors complicated simple tasks such as writing and drinking from a glass of water.

Before she underwent treatment, Smith told CTV News that she was too embarrassed to go out and socialize due to her tremors.

“My life has really diminished somewhat because of this,” she said. “It’s demeaning, depressing.”

But after the ultrasound treatments, Smith saw considerable improvement in her movements.

“I will be able to sign my husband’s 50th anniversary card,” the Bobcaygeon, Ont., resident told CTV News after undergoing a successful treatment last Friday morning.

Tony Lightfoot, a 73-year-old Calgary resident, was one of the first patients treated with focused ultrasound thalamotomy in 2012, with doctors targeting his right hand.

Four years later, Lightfoot says he feels “so much better.”

“From what I’ve observed, (the hand) is about 99 per cent steadier than what it was,” he said. 

However, the treatment doesn’t work for some patients. Doctors don’t know why and are conducting more research.

Side effects can include problems with walking and a sensation of pins and needles, but those are usually temporary and resolve with time, doctors say.

The study published Wednesday was partially funded by InSightec, a company that develops and distributes non-invasive medical technologies such as the MRI-guided focused ultrasound. 

With a report from CTV’s medical specialist Avis Favaro and producer Elizabeth St. Philip