This Non-Invasive Brain Surgery Is a Cut Above

A team of Canadian researchers are pioneering focused ultrasound to treat a variety of brain disorders without ever making an incision.


It has been 10 years since researchers at Sunnybrook Hospital became the first in Canada to perform clinical trials to treat essential tremor without cutting into the brain.

“It was a major shift away from the conventional treatment of essential tremor, which typically is open brain surgery; this was a less invasive approach, without scalpels or incisions,” said Nir Lipsman, neurosurgeon and director of the Harquail Centre for Neuromodulation at Sunnybrook, in a press release.

“Focused ultrasound was then, and continues to be, a game-changing innovation in the treatment of brain disorders.”

Essential tremor is a common condition, but it has a big impact on quality of life. Patients with essential tremor experience involuntary shaking in the body, primarily in their arms and hands. This makes it difficult to carry out almost any everyday task.

The new approach uses MRI to provide medical imaging in real time so that surgeons can visualize brain lesions that cause essential tremor as they work. Guided by the MRI images, patients are treated using a specialized helmet that precisely targets high-intensity ultrasound energy to the brain lesions. More than 1,000 beams converge on the target to produce focused heat, destroying the unwanted tissue without ever cutting the skin.

The patient is assessed for functional improvement during the treatment to make sure it’s working as expected. The procedure gives significant improvement in symptoms, giving patients back their independence without having to open the skull or cut through healthy tissue to get to the target.

Four years after their first procedure, Health Canada and the US FDA approved focused ultrasound for use in patients. In all, nearly 280 patients have received treatment at Sunnybrook.

Sunnybrook’s early adoption of this technology means they have grown their expertise over time, both shortening treatment and recovery time for patients, and expanding the list of conditions they can treat.

They made several world firsts with by combining low-intensity focused ultrasound with microbubbles to temporarily open the blood-brain barrier. Their first trials allowed them to deliver chemotherapy to the brain. They went on become the first in the world to use the same approach to treat Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis (ALS). The same temporary opening can also be used to diagnose brain cancers by looking for biomarkers that can cross into the blood.

Sunnybrook researchers were also the first in North America to use high-intensity focused ultrasound to treat severe depression and obsessive-compulsive disorder. For patients who are not responding to standard treatment, this is a non-invasive way to treat areas deep in the brain without scalpels.

Being able to treat these conditions without cutting into the brain means better outcomes for patients. There is reduced risk of infection or blood clots, and lower risk to healthy brain tissue. Patients can also stay awake throughout the procedure, eliminating the need for general anaesthesia. Most patients can go back to their normal routines within a day.

Having already been tested on one of the most unforgiving organs, focused ultrasound may also be useful outside the brain. With continued innovation, Canada can lead the way to more treatments for patients around the world.

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Karyn Ho is a science animator and engineer who thrives at the interface between science, engineering, medicine, and art. She earned her MScBMC (biomedical communications) and PhD (chemical engineering and biomedical engineering) at the University of Toronto. Karyn is passionate about using cutting edge discoveries to create dynamic stories as a way of supporting innovation, collaboration, education, and informed decision making. By translating knowledge into narratives, her vision is to captivate people, spark their curiosity, and motivate them to share what they learned.