A new minimally invasive approach to treat essential tremor through ultrasound waves sent to the brain was approved last July by the FDA. This innovative system has the advantage of avoiding the risks of a brain surgery. But it has an ethical downside: It burns part of the brain cells. And there are no studies yet about the long-term effects.
Kristin “Sunny” Berry first noticed the tremor in her hands at school when she was 7 years old. It has gotten worse through the years, affecting her head and making it difficult to even eat, get dressed, or write. “Brushing my teeth was just a nightmare; I could write but nobody could read it,” she told to MedicalExpo e-mag during a phone interview.
She started looking on the Internet and found out about the HIFU procedure—High Intensity Focused Ultrasound treatment—performed by a couple of centers in the world, including Ohio State University Wexner Medical Center. She decided to apply. It was like a dream come true for Kristin. In mid-April, after a four-hour-session, she came back home without almost no shaking in her hands or head. “I could feel the difference right away—it was amazing,” she said.
Effects Are Immediate
The system is pretty simple. The patient puts on a helmet at the beginning of the procedure. This helmet has over a thousand ultrasound probes that will deliver the energy inside the brain. Then the person lies down on a MRI table so doctors can obtain images of the brain. When they get these pictures, they locate the area called the thalamus. It is a central structure of the brain that possesses over 120 components. One of these components is involved in generating the tremors.
Once doctors have identified this area, they apply ultrasound waves that traverse the skull and converge to the targeted area where they generate energy—about 1,000 watts that slowly heat up that part of the brain. By heating it up, the system burns away certain brain cells that are causing the tremor. The company InSightec manufactures the ExAblate Neuro, the focused ultrasound device approved by the FDA.
“The patient receives no anesthesia—they are awake the whole time and interacting with us,” explained Dr. Ali Rezai, director of the Center for Neuromodulation at Ohio State’s Neurological Institute. “We do tests first. So we deliver small amounts of the energy to see if there’s any benefits or any side effects. If the patient doesn’t report any problem after 10 or 15 minutes, then we increase the energy.” The patient sees the changes directly on the MRI table.
Not a First- or Even Second-Line Therapy
“This new technique is advantageous because it is basically performing a brain surgery without cutting the skin or opening the bone. It’s minimally invasive,” said Dr. Rezai. Still, one major issue remains: The ultrasound waves are actually burning a part of the brain, and the cells that are burnt won’t regenerate.
Dr. Rezai acknowledges that it is an important point. “That’s why we don’t do this approach as a first-line therapy or even second-line. We are talking about patients who have tried various medications and other treatments, and despite the best attempts for years their tremor has become so severe that they have difficulty with basic activities like eating, dressing themselves, writing, working. So it comes to a point where they become very disabled.”
According to him, burning the brain or the nerves is commonly used worldwide for example to treat chronic pain. Kristin, for her part, “tried not to think too much about that.” “It was worth it and I would do it again” if needed.
Plans to Treat Depression or Compulsive Disorder
Rezai acknowledged, “Yes, if you don’t target exactly in the precise area, it’s possible that the patient may have problems in terms of sensation loss, or difficulty speaking or moving, but it’s extremely rare. The safety profile is very strong with this,” he added.
Side effects included sensory and gait disturbances.
A randomized trial was published in The New England Journal of Medicine on August 25. In this study involving 76 patients with medication-refractory essential tremor, transcranial-focused ultrasound thalamotomy significantly reduced hand tremor at three months, and the effect persisted during the 12-month study period. Side effects included sensory and gait disturbances. But there are no studies yet to tell what could be the effects over two, three, or five years.
“I don’t think there could be a side effect because if there was a big problem you would see it right away on the patient, but the issue could be the tremor coming back,” said Dr. Rezai. According to him, this approach is CE-certified for Parkinson’s disease. Researchers are now looking into ways to use it to treat epilepsy, depression or even obsessive-compulsive disorder.