Mar 23, 2022

Interviewer: Focused ultrasound to treat essential tremor and how to decide if it's a good option for you. Dr. Shervin Rahimpour is a neurosurgeon who specializes in the treatment of essential tremor. Who is a good candidate to get relief if they have tremor symptoms using this treatment? Let's just start there.

Dr. Rahimpour: Essential tremor is the most common movement disorder and affects upwards of 10 million people in the United States. It's characterized by this either postural tremor when you try to maintain a posture with your hands or it can be brought about when you're trying to perform some kind of physical action with your hands. And it doesn't necessarily just affect the hands. It can affect people's voice, their balance, and other extremities.

While there are effective medications for essential tremor, some patients don't either respond to these medications or have bad drug side effects, and we have good interventions to try to treat this surgically.

Interviewer: And is there somebody in particular, beyond perhaps medications don't work or they'd react badly to them, that would be a good candidate for this particular surgery?

Dr. Rahimpour: Yeah, it could be the case that the medications work but just not enough. So you could imagine if your hands are shaking, whether it's affecting your work or just even trying to feed yourself, this can be really debilitating. So if the medications make the tremor a little bit better but not quite to where you need it to be, to be functional, that's where surgical intervention can play a significant role.

Interviewer: And if somebody comes into your office, what process do you go through to determine if they're a candidate?

Dr. Rahimpour: First, we make sure that they've actually exhausted their medical options. Obviously, we don't want to perform surgery on someone that could otherwise be treated with medications.

The next step is we assess their tremor. Sometimes patients are misdiagnosed, so we want to make sure they actually have essential tremor and not some other kind of movement disorder.

Once we've confirmed that, we assess their surgical candidacy. We look at their MRI imaging to look at their brain anatomy.

And then we discuss some of the options that are available to them. Currently, we have two different treatment options for essential tremor. Historically, the mainstay of surgical management of essential tremor has been deep brain stimulation, which involves placing electrodes in the sweet spot of the brain called the thalamus where we believe is a critical area for essential tremor.

This treatment involves two stages. One is placement of the electrodes in the brain during an awake surgery to make sure that we are providing adequate tremor relief, and then a second stage, which involves connecting those wires to a battery typically in the chest pocket, like you would for a pacemaker.

Now, this therapy is not necessarily for everyone. Certainly, for patients who don't want an open surgery, and also those that may not qualify as a good surgical candidate. And that's where I think focused ultrasound can play a significant role.

Interviewer: And how does focused ultrasound work then?

Dr. Rahimpour: Yeah. So focused ultrasound . . . similar to the way a magnifying glass focuses a beam of light to a point, acoustic lenses can be used to focus sound to a point. And so we use this principle to focus sound energy to that same spot in the brain, the thalamus, to try to disrupt the circuit that's causing a patient to have tremors.

Interviewer: This is non-invasive completely?

Dr. Rahimpour: Yeah, absolutely. So it involves a couple of things. One is to shave the head entirely, and other than that, there are no incisions, and typically, patients leave the hospital the same day.

Interviewer: Wow. And what about relief from the tremors? Does that develop pretty quickly as well?

Dr. Rahimpour: Yeah. That, we expect to be immediate. The caveat currently is that we can only treat one side of the brain. So for patients who might, say, be right-handed, treating their left brain for their right hand can mean a significant improvement in their quality of life.

Interviewer: And I've heard this procedure could also be used for Parkinson's. Is that true?

Dr. Rahimpour: Yeah. So for patients who have a tremor-dominant Parkinson's disease, focused ultrasound can also be an option. And then recently, as of last year, it's also FDA approved for other symptoms of Parkinson's, not just the tremor. Other symptoms include things like bradykinesia or rigidity, so difficulties initiating movement or moving.

Interviewer: If somebody is eligible for focused ultrasound, what considerations would a patient go through to determine if that's the treatment that they want to pursue?

Dr. Rahimpour: Yeah, so similar to deep brain stimulation, we want to make sure that the patient has the appropriate diagnosis for essential tremor, again, because a lot of things can mimic this disease.

So patients have to ask themselves whether or not they are willing to undergo an open surgery, which is deep brain stimulation. And if they're not, then this gives them a nice alternative option.

Patients who undergo evaluation for focused ultrasound should also consider potential side effects from this treatment. That includes temporary ones, like having some numbness and tingling sensations on the same side as their tremor, as well as potentially a brief period of time after the procedure of poor balance.

As the swelling develops from the treatment over the course of the next several days to weeks after the procedure, sometimes these symptoms can get a little bit worse before getting better. And by three months out to a year of follow-up, we don't expect these symptoms to persist.

Interviewer: Are there any long-term type symptoms that a patient should be aware of?

Dr. Rahimpour: Very rarely can these paresthesias or the sensation of numbness and tingling persist at a year's time, and the same goes for balance and abnormal gait.

One part of our pre-procedural evaluation involves an evaluation by our physical therapist, who assesses patients' gait and balance to ensure that we have a good adequate baseline before undergoing this procedure.

Interviewer: For somebody with essential tremor, when you use the focused ultrasound to reduce their tremors, how does that impact their quality of life?

Dr. Rahimpour: Treatment with focused ultrasound to reduce tremor can have a very meaningful impact on one's quality of life. It gives them the ability to do some of the hobbies that they enjoy and certainly some basic tasks like feeding themselves.

Interviewer: After somebody has had a focused ultrasound to treat tremor and, say, the tremor starts coming back after a period of time, the three years that you mentioned, can they get the focused ultrasound again?

Dr. Rahimpour: Absolutely. We can reevaluate them in clinic to see what their options are.

Interviewer: And if at that point they've also decided, "Well, maybe I want to try the deep brain stimulation at this point," is that another option?

Dr. Rahimpour: Yes, that can also still be on the table as an option.

For Patients