New advances for reducing tremors are improving the quality of life for people with Essential Tremor (ET) and Parkinson’s disease (PD). With applied pulses of focused ultrasound to the brain, dreams can become reality.
The defining feature of those suffering from Parkinson’s disease is tremors, which are involuntary muscle movements that occur in all parts of the body, most commonly in the hands. Patients with Essential Tremor – a disease that affects the nervous system– also experience involuntary and rhythmic shaking. PD and ET combined affect millions of people all over the world [1].
When medications do not work, the usual treatment to reduce tremors is deep brain stimulation. Deep brain stimulation works like a pacemaker in the brain by surgically implanting a small electrode connected to a pulse generator. One major risk of deep brain stimulation is an increased likelihood of bleeding and infection, as is the case with any invasive surgery [1].
Thanks to groundbreaking advancements in the field, there is now a new treatment option: magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy. The focused ultrasound treatment is a non-invasive interventional radiology procedure where “focused beams of sound energy are used to heat and destroy a small part of a structure in the brain called the thalamus. The procedure gives relief to the opposite side of the body, meaning that treatment to the right side of the brain would relieve tremors on the left side of the body, and vice versa.” [2]
The way the focused ultrasound works can best be understood with an analogy. Imagine shining a magnifying glass on a leaf; the sunlight shines through the magnifying glass and its sunrays all converge to burn a hole on a single point in the leaf. “With focused ultrasound, an acoustic lens is used to concentrate multiple intersecting beams of ultrasound on a target deep in the body with extreme precision and accuracy. Depending on the design of the lens and the ultrasound parameters, the target can be as small as 1x1.5mm or as large as 10x16mm in diameter”. The technology utilizes low or high pressure waves to apply both thermal and mechanical energy [3].
The non-invasive procedure avoids the risk of infections and bleeding from surgery, as well as the time of treatment delivery. Whereas deep brain stimulation needs time to adjust for electrostimulation, the focused ultrasound delivers its effect immediately. The new treatment is also less painful, requires a shorter time of hospitalization, and substantially and immediately reduces tremors [3].
Dr. Federico Bruno led the study titled “Efficacy of tc-MRgFUS Thalamotomy in The Treatment of Essential Tremor (ET) and Parkinson Disease (PD) Tremor: Experience From 39 Patients in A Single Centre with Long Term Follow-Up”. The study utilized a study cohort of patients (average age 64.5 years) who experienced tremors for more than 10 years; researchers assessed the tremor severity and quality of life for these patients before focused ultrasound treatment, immediately after treatment, and over the year after treatment. They found that in 37 of 39 patients, about 95%, had an immediate and significant reduction of tremors, and the tremor reduction remained consistent over the course of the year following treatment. Quality of life improved for the 18 ET patients and 21 PD patients [4].
These are really exciting and promising results and, as more findings regarding the treatment get published, the number of focused ultrasound sites could expand, especially with its clinical use approved by the FDA in 2016. An obstacle remains, however, as there are limited specialized centers that offer this technology and not many patients are aware of this treatment option. Furthermore, there are additional challenges to overcome in the near future, including the precision of neuroimaging techniques. Overcoming these obstacles will require attention to detail, implementation, and monitoring in order to expand the availability of focused ultrasound treatment [2].
The future possibilities are endless. More research and development may yield the possibility of treating both sides of the thalamus, as well as using the focused ultrasound technology for disorders other than tremors. There are currently clinical trials to use this technology for other neurological conditions like obsessive-compulsive disorders, epilepsy, neuropathic pain, and even brain tumors [5].
Focused ultrasound is a new and exciting treatment for tremors that is minimally invasive, safe, and well-tolerated by patients. It brings an alternative treatment option to the table for PD and ET patients, with a high efficacy rate. More research can expand sites that deliver this treatment, as well as treat other neurological conditions.
References:
1) Essential tremor - Symptoms and causes. (2019, January 23). Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/essentialtremor/symptoms-causes/syc20350534#:%7E:text=Essential%20tremor%20is%20a%20nervous,a%20g lass%20or%20tying%20shoelaces.
2) FDA. (2016, July 11). FDA approves first MRI-guided focused ultrasound device to treat essential tremor. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/fdaapproves-first-mri-guided-focused-ultrasound-device-treatessential-tremor
3) Focused Ultrasound Foundation. (n.d.). Overview. https://www.fusfoundation.org/the-technology/overview
4) Panebianco, L. (2019). Minimally Invasive Procedure Relieves Tremors in Parkinson’s Patients. Radiological Society of North America, 1-3. http://press.rsna.org/timssnet/media/pressreleases/14_pr_target.cfm? id=2124
5) Focused Ultrasound Foundation. (n.d.). Find a Clinical Trial. https://www.fusfoundation.org/for-patients/clinical-trials
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