On December 18, 2018 an important press release was issued by Insightec, the manufacturer of the MRI-guided Focused Ultrasound (MRgFUS) device used at Sperling Neurosurgery Associates to treat essential tremor (ET). The press release held very good news for people with tremor-dominant Parkinson’s disease (PD). In short, the U.S. Food and Drug Administration (FDA) approved MRgFUS to treat these PD patients.
MRgFUS for ET
MRgFUS is an incisionless (noninvasive) treatment that uses over a thousand “beams” of ultrasound to deaden a very tiny area of the thalamus called the VIM nucleus. The clinical term used by neurosurgeons for this procedure is thalamotomy, which can also be done by drilling a hole in the skull and inserting a radiofrequency probe to accomplish the same purpose. You can understand what an enormous innovation Insightec achieved when they developed the technology to integrate MRI treatment planning and guidance to deliver ultrasound without breaking skin or drilling through bone!
The VIM nucleus does not itself cause tremor signals, which originate further back in a brain area called the cerebellum. It does, however, play a key role in forwarding tremor messages from the cerebellum to the outer part of the brain called the motor cortex that directs hand movement. By interrupting the flow of tremor messages at the VIM, the motor cortex will allow the hand to move as usual without the extra confused signals. That’s how MRgFUS works for ET, and it was FDA-approved in 2016.
MRgFUS for tremor-dominant PD
Hand tremors (and other parts of the body) are often a symptom of PD, though they are different from those of ET. In ET cases, the tremors are called action tremors. For example, a person with ET is sitting at the breakfast table, hands resting on the table with no visible shaking; but, in the act of reaching for the coffee cup, they get “the shakes.” Unlike ET, most PD patients experience fewer action tremors but more resting tremors: in a PD breakfast scenario, the hands resting on the table are visibly trembling even though no action is involved.
A subtype of PD that is estimated to affect 10-20% of patients is tremor-dominant PD. Although tremor-dominated PD generally does not progress quickly during the early stages, tremor is the primary symptom and can be quite agitated. Severe hand tremors are debilitating because they interfere with normal daily activities such as eating, drinking, dressing oneself, writing or typing, etc. When medication is not effective, the tremors are called refractory, and neurosurgery may be recommended.
Until recently, the surgical intervention most widely used has been Deep Brain Stimulation (DBS), which involves implanting electrodes in the brain plus a powerpack in the chest. In most instances, this is a safe and effective procedure, but many patients are hesitant due to the invasiveness and risks of the treatment.
Now, thanks to FDA approval of MRgFUS, patients with tremor-dominant PD have an alternative. The approval came following publication of a December, 2017 paper titled, “Safety and Efficacy of Focused Ultrasound Thalamotomy for Patients With Medication-Refractory, Tremor-Dominant Parkinson Disease.“i As with the ET treatment, the target of MRgFUS for tremor-dominant PD is the VIM nucleus of the thalamus so it is an incisionless thalamotomy.
According to one of the paper’s authors, Dr. Jeff Elias, “Patients are attracted to the less invasive aspects of focused ultrasound. Now Parkinson’s patients, for whom tremor is their primary disability, have more treatment options than conventional cranial surgery. While focused ultrasound is not curative for Parkinson’s disease, it can provide significant quality of life benefits.”ii
Regaining quality of life means not only performing tasks, but also getting back into professional, social and recreational activities. It’s almost like coming home to the lifestyle you used to live. If you have ET or tremor-dominant PD that no longer responds to medication, and you are considering DBS, contact us for information about MRgFUS or a consultation. Learn more at Sperling Neurosurgery Associates.
iBond AE, Shah BB, Huss DS, Dallapiazza RF et al. Safety and Efficacy of Focused Ultrasound Thalamotomy for Patients With Medication-Refractory, Tremor-Dominant Parkinson Disease: A Randomized Clinical Trial. JAMA Neurol. 2017 Dec 1;74(12):1412-1418.
ii“INSIGHTEC Announces FDA Approval of Exablate Neuro for the Treatment of Tremor-Dominant Parkinson’s Disease.” Press release, December 18, 2018. https://www.prnewswire.com/news-releases/insightec-announces-fda-approval-of-exablate-neuro-for-the-treatment-of-tremor-dominant-parkinson-s-disease-874689536.html