If you've ever watched an interview with a celebrity or spokesperson with Parkinson's disease, you may see some twitching or jerking. Often, those movements aren't due to the Parkinson's — they're actually a side effect of medication.
While there is no cure for Parkinson's disease, many patients find relief from some of the worst symptoms, such as rigid muscles, with prescription medication. They can help patients improve speed and coordination, and lessen tremors.
Unfortunately, these medications sometimes have challenging side effects. One of the main side effects of medication for Parkinson's is involuntary, unusual movements (dyskinesia). While these movements may be easier to manage than major symptoms of Parkinson's, they can still be very frustrating. And what's even more frustrating is that there are limited treatments available to combat this side effect.
That's why Penn Medicine offers a treatment option known as MRI-guided focused ultrasound, to improve dyskinesia in patients taking medication for Parkinson's disease. It is also FDA-approved for essential tremor.
Casey H. Halpern, MD, Chief of Stereotactic and Functional Neurosurgery at Penn Medicine, is a leading international expert in this treatment.
Q: What are traditional types of treatment for this side effect of Parkinson's Disease medication?
Dr. Halpern: Deep brain stimulation (DBS) has traditionally been used to treat dyskinesia caused by Parkinson's disease medications. DBS is an open brain surgery where we insert two wire electrodes deep into the brain to reach the structures that cause the involuntary movements. Then, we implant a small impulse generator battery — sort of like a pacemaker — into the chest. The generator sends an electrical impulse to the part of the brain that controls movement. You will get a controller to turn the device on and off. DBS is very successful. Our Parkinson's Disease and Movement Disorders Center is one of the largest centers of its kind in the country, and we have performed more than 1,200 procedures, helping patients tremendously. However, it is an open surgery, which does carry risks, such as blood clots or serious infections.
Focused ultrasound, on the other hand, is non-invasive but may not be as helpful to patients with symptoms on both sides of their body. Thus, we always treat the more severely affected side with focused ultrasound rather than bilaterally as we do with deep brain stimulation.
Q: What exactly is focused ultrasound?
Dr. Halpern: Focused ultrasound is a non-invasive, non-surgical procedure that induces an ablation in a zone that helps with symptoms in tremor and Parkinson's. We use focused ultrasonic waves to create a distinct thermal lesion deep in the brain without injuring surrounding structures. We are specifically targeting the basal ganglia. This is a group of structures in the brain that are involved with movement control and coordination. During the procedure, we use a magnetic radiofrequency imaging (MRI) thermal imaging system. This measures temperature changes in the skull, and helps us make sure we're keeping the patient safe.
It's a great procedure because we can work on very delicate areas safely and effectively, with very few side effects.
Q: What are the benefits of a non-invasive procedure like focused ultrasound?
Dr. Halpern: There are several reasons why we try to do non-invasive procedures when possible. We don't have to make any large cuts or put anything directly into the brain. We're not drilling holes, and there's no hardware.
Non-invasive procedures are also great for people who can't get open surgery. They may be a high-risk patient — for example, someone who is obese, which increases the risk of complications during surgery. Or, they may be nervous about the concept of surgery directly on the brain.
Q: Sounds great, but are there any risks?
Dr. Halpern: Just because focused ultrasound is not invasive doesn't mean it comes without risks. We're still creating a thermal lesion or ablation in the brain. If we make it too big, it could cause slurring of words or balance issues. Also, we're targeting a specific area of the brain, that is just above the track that leads to the visual cortex. If we hit this track, we could cause vision problems. Motor function is also nearby, so we use MRI in real-time like a heat map to ensure safety to the best of our ability.