For 15 years, tremors controlled Tony Lightfoot’s body.
The petrochemical engineer couldn’t stop his arms from shaking. He got by at first; he typed instead of wrote and used two hands to steady his bowl of porridge in the morning. But the intensity of the tremors escalated; in meetings with clients, he couldn’t turn the pages of a proposal without shaking. His driving became jerky. His wife helped dress and feed him. When he was nervous or stressed, his body would shake from his stomach through both arms. And there were uncontrollable spasms. “I would take something out of the fridge and think I had it, and then I’d throw it and it would be all over the kitchen,” says Tony, 68. “It got so bad, I would cry at times.”
Tony suffers from essential tremor. It is the most common type of movement disorder, affecting roughly three per cent of the population. It usually appears in late adulthood and often runs in families. Malfunctions in the thalamus, a part of the brain that relays information to control muscle movements, cause the tremors. Instead of being smooth and continuous, the signal running through the thalamus is jumpy.
Medication works for most people with essential tremor, but for some, including Tony, the symptoms return. The remaining options were brain surgery to interrupt the circuit with the “jumpy” signal causing the tremor or deep brain stimulation to turn it off, in which a pacemaker fires electrical signals into electrodes implanted into the faulty brain tissue. But he wasn’t keen on open surgery. Instead, he turned to the Internet in search of something better.
A YouTube video changed Tony’s life. The video showed how focused ultrasound treatment improved another man’s essential tremor. The procedure concentrates beams of ultrasound waves onto an area no larger than a pinhead to heat and destroy the troublesome cells without cutting open the skull. Tony was impressed and started making calls. His persistence paid off; in December 2012 he joined a Canadian-first clinical trial at Sunnybrook to test the procedure’s safety.
Only six people with essential tremor have been treated with focused ultrasound at Sunnybrook so far, but Dr. Michael Schwartz, head of the division of neurosurgery at Sunnybrook and the study’s principal investigator, says the procedure appears to be safe and has very few side-effects. It requires no general anesthesia. “It’s been really good for them, and it’s very exciting for me,” he says.
The difference in Tony’s ability to complete simple tasks before and after the procedure is stunning. He couldn’t drink from a cup without spilling, nor could he draw a spiral; his pen only jabbed at the paper. But immediately after the doctors had burned a tiny hole in his brain, he was able to move his arm without shaking. “It was wonderful. I couldn’t believe it,” he says. “They asked me to write and I wrote for the first time in 10 years.”
Sunnybrook is one of only a few centres in the world with the technology to deliver focused ultrasound. The scientists and clinicians at Sunnybrook’s Centre for Research in Image-Guided Therapeutics (CeRIGT) are finding new ways to deliver non-invasive treatments to hard-to-reach parts of the body without general anesthetic or the risks of traditional surgery, such as bleeding or infection.
Imaging technologies such as ultrasound and magnetic resonance imaging (MRI) have been used largely to diagnose health problems. The idea of using ultrasound to destroy millimetre-sized bits of tissue has been around for a while, but it remained impractical because doctors couldn’t precisely aim the energy beam. MRI gave doctors the richly detailed view of the inner body they needed. Together, MRI and focused ultrasound offer the possibility of healing without cutting.
But neurosurgery remained a challenge. “The skull surrounds the brain, and most of the ultrasound energy is absorbed by the skull itself,” says Dr. Schwartz. The skull would heat up and disrupt and weaken the beam. Dr. Kullervo Hynynen, head of CeRIGT and Director of physical sciences at Sunnybrook Research Institute, found a solution. He pioneered the use of MRI to guide focused ultrasound to destroy damaged brain tissue by creating a helmet-like device called a hemispherical transducer. It focuses the ultrasound beams into the brain in much the same way a magnifying glass concentrates sunlight into one spot. He also designed a cold-water cap to keep the head from heating up.
Almost nothing is left off the list of potential targets. Dr. Schwartz says he hopes to adapt the procedure to treat trigeminal neuralgia, a shooting debilitating pain in the face. Other studies are looking at whether the technique can be used to temporarily open the blood-brain barrier that normally protects the brain from foreign molecules to allow medicine into the brain to treat tumours, Parkinson’s and Alzheimer’s diseases. In addition to brain applications, the CeRIGT research teams are developing high-intensity focused ultrasound to treat cancers that have spread to the spine and uterine fibroids (painful non-cancerous tumours).
Focused ultrasound treatments offer a glimpse of the future of medicine, a way to erase a damaged piece of tissue deep inside the body, keeping the rest unblemished. “The only limit is the imagination,” says Dr. Schwartz.
The photographs show the procedures that cured patient Tony Lightfoot’s tremors by the pioneering use of focused ultrasound through the skull and into the brain. Middle of bottom row: Dr. Kullervo Hynynen (centre) and colleagues monitoring the treatment.
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