Cerebrum Winter 2021

Focused ultrasound to treat essential tremor is available at two dozen institutions in the US, and the University of Maryland was an early site for treatment and contributor to clinical trials.

ability to write, eat, dress themselves, and work. Currently, a new trial we are conducting is directed at bilateral tremor (tremors on both sides), and we are also trialing focused ultrasound to treat symptoms of Parkinson’s disease, to reduce neuropathic pain, and to improve visualization and drug delivery for the treatment of brain tumors. Focused ultrasound treatment requires that patients first undergo a series of tests for eligibility. A CAT scan reveals if their skull has the required density for treatment. On the day of treatment, a neurosurgeon places a stereotactic frame on the patient’s head. A bag of cooled water sits on their scalp to reduce heating of the skull. The patient lies on the MRI table, where this frame and bag meet a hemispherical array. In this array, approximately 1,000 sound-emitting elements can be individually steered and converge on a single target where these beams meet within the brain. With this technology, acoustic beams burn a hole the size of a quinoa seed in the thalamus, disrupting a circuit known to underlie essential tremor, all while the patient is awake and under real- time MRI. Williams decided that the time had come to try it. “Are you anxious at all?" I asked him. “Honestly, my wife is more scared than me,” he said, smiling at Carol. Our staff wheeled him to our focused ultrasound suite. A neurosurgeon specializing in movement disorders placed a stereotactic frame (a square of hard plastic) on his head. This would allow the focused ultrasound workstation to marry his MRI with his prior CAT scan imaging. We sat him down on the MRI scanner and connected his frame to the hemispherical array with a bag of continuously cooled water in between. With imaging, we located the left ventral intermediate nucleus, a segment of the thalamus involved in the circuit that underlies tremor, called the dentatorubrothalamic tract. Disrupting this tract, as DBS does, allowed us to affect his right hand. In sequential steps, our team directed these elements and applied sound. After each treatment, Williams’ tremor was tested to determine the procedure’s effect. He was asked to draw a straight line and then to accurately draw a spiral within boundaries on a sheet. With each dose of sound energy, his attempts became more precise. “It was a strange experience,” he said. After an hour—his treatment concluded—an MRI demonstrated successful destruction of the left ventral intermediate nucleus. At the recovery area, his stereotactic frame was removed.

Our nurse handed him a pen and paper. With Carol at his side, Williams adeptly wrote his name. Seeing this, she almost broke down in tears. “I was not able to do that for many years,” he said. “I’ve been re-training my right hand for eating and shaving now that I can use it again.” A month later, he was using his right hand again. “It seems miraculous to me,” said Williams. l Focused ultrasound has the potential to treat Alzheimer’s, Parkinson’s, and more, and president-elect Joe Biden, author John Grisham, and the Michael J. Fox Foundation have showed their support.

Abdul-Kareem Ahmed, M.D., is a neurosurgery resident at the University of Maryland Medical Center.

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