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When a dentist was unable to continue his practice due to a hand tremor, a novel treatment was successful with a targeted dose of sound waves aimed at a tiny region near the center of the brain, as described by neurosurgical resident Dr. Abdul-Kareem Ahmed in the Washington Post for March 1 . Technology has affected our lives for good or ill, but this impressive application had the immediate effect of allowing the patient to return to a more normal life, without surgically entering the brain.
At the University of Maryland Medical Center, a helmet surrounded the patient's head with an array of ultrasound generators carefully aimed at a region that relays information from the cerebellum, known to help smooth out guided movements like those needed for using a pen or a spoon. This region, located in the thalamus, was mapped using magnetic resonance imagery (MRI). When the sound waves converged, neurons in that region were heated up to a level that successfully reduced the tremor.
With each application, explained Ahmed:
"A neurologist tested the patient’s right hand tremor, asking him to trace between two lines and to draw a spiral. This millimeter march progressed for two hours, until the neurologist tested his tremor one more time. ‘If you had this control, this exact control for the rest of your life, would you be happy?’ he asked our patient.
‘Extremely happy,’ he responded.
With that, his treatment ended. He was gently helped off the table. …A nurse gave him a pen and paper to demonstrate his control. He signed his name with delight, grinning at his penmanship”
The article emphasized how the doctors not only mastered the treatment technique, but also took into account the whole person, and how his tremor and its improvement affected his work, preferences, and hobbies.
If you have ever seen how a magnifying glass can focus the sun’s rays to provide high-intensity heat at the focus point, you can imagine how focused ultrasound can affect a small target without damaging surrounding tissue. This use was patented in 1992, then transferred to Insightec in Israel in 1998. That company’s product, the ExAblate 2000, later obtained US FDA market approval.
Ultrasound is defined as sound waves above the upper limit of human hearing (20,000 cycles per second or Hertz) and can go much higher. Its use in medical imaging, such as ultrasonography in pregnancy, is well known. The disorder described here is called essential tremor, but use of this method in Parkinson's Disease is being explored, as are disorders in the prostate and elsewhere.
References
Ahmed, Abdul-Kareem (2020). His hands shook-uncontrollably for a decade. MRI guided ultrasound surgery finally relieved the tremors. Washington Post, March 1.
