For the time being, there's more research and development in the ET field than the PD field as it relates to tremor dominant Parkinson's. Here's a few links that compares the two.
neurologyreviews-digital.co...
essentialtremortreatment.co...
jnnp.bmj.com/content/early/...
michaeljfox.org/news/focuse...
neurologylive.com/view/stem...
RKM
Brain surgery without an incision
Focused Ultrasound for Parkinson's: A Two-Part Webinar Series by the FUS Foundation
Focused Ultrasound for Freezing of GaitDr. Jeanmonod, neurosurgeon at the SoniModul Clinic in Solothurn, Switzerland who is a pioneer of the MRg FUS PTT 
Has anyone investigated or had a focused ultrasound procedure done. I would like first-hand information, as I am looking into it for John. 
