I thought the purpose of this procedure was to sever a connection (ie, interrupt a circuit) in the brain, which is accomplished by destroying some cells...not necessarily target the STN for destruction. Now, are those cells in the STN abnormal? I didn't think so, and have never heard of this before.
And saying those cells in the STN must be abnormal or we wouldn't have PD is assuming they are the cause of PD, and I have never heard of that before, either. If that's true, why doesn't this procedure work for all PWP and abolish all symptoms?

I can't forget Dr. Jannetta's theory that PD is caused by a cerebral artery impinging on nerves in the brain and irritating them...he treated that lady for trigeminal neuralgia (who also had well documented PD going back 8 or 9 years, I think it was) and upon awakening, discovered that not only was her trigeminal neuralgia relieved by the Teflon pad placed under the cerebral artery in her brain, but her PD was gone. Her PD symptoms returned months later and on MRI they discovered the Teflon pad had slipped, so they had to go back in and secure it...and PD symptoms abated again. Seems pretty convincing of a cause and effect to me, at least for that patient. I've not been able to find out any more about that patient or Dr. Jannetta, though I have tried.

If they are actually targeting the STN for destruction, that seems a much more radical (and scary!) procedure than just severing a nerve connection in the brain (which is still scary!!).