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A recent development in the treatment of Parkinson's disease is focused ultrasound. Does this replace DBS surgery? What are the arguments for each?
Until the early part of the 21st century, Parkinson's had two surgical treatments called thalamotomy and pallidotomy. I've described them in a previous blog post. These procedures have been replaced with deep brain stimulation (DBS) surgery, also in a previous blog post.
Now, there is an emerging option called focused ultrasound. In this procedure, an MRI locates the target in the brain, then beams of ultrasound, coming from different directions, converge on the target, destroying the neurons. Its effect is that of pallidotomy or thalamotomy without holes in the skull or probes in the brain.
Here are some considerations in choosing between them.
Reversibility. DBS surgery is reversible. If it doesn't work or if something better comes alone, the electrodes can be removed with no aftereffect, and once the patient's hair has regrown, no indication the surgery ever happened. Focused ultrasound is not reversible. Once the neurons have been killed, they're dead.
Adjustability. DBS stimulation is adjustable. The patient or a caregiver can modify the signal, which makes it valuable for a disease like Parkinson's, where the symptoms can vary from hour to hour. Focused ultrasound is not adjustable. The dead neurons won't revive and the surviving ones won't change.
Correctability. With any of these procedures, one risk is that they will miss the target. The DBS electrodes will be in the wrong spot or the wrong neurons will be destroyed. DBS surgery can be corrected by removing and re-implanting the electrodes. Focused ultrasound is permanent.
Surgical risk. DBS surgery, like any operation, has risks. The biggest one is that inserting the electrode could rupture a blood vessel causing a stroke. The surgery also carries a risk of infection. The consequences of these can be severe, becoming debilitating or even fatal. The likelihood of either one occurring is minimal. Surgeons have become adept at avoiding them. But the risk is not zero. Focused ultrasound, being non-invasive, does not carry these risks.
Fear. DBS is frightening. To submit to someone drilling holes in the skull and sticking wires into the brain demands a certain level of trust and desperation. Fear has deterred many Parkinson's patients from getting treatment that would help. Focused ultrasound, which carries few of the dangers and inconvenience of surgery is less frightening.
Maintenance. DBS surgery requires maintenance. The battery will deplete and will have to be replaced. That's day surgery, but it's still surgery. And people with the implants have to be wary of electromagnetic radiation such as security scanners at airports or even at retail stores. Focused ultrasound carries none of these concerns.
So which is better? That's a conversation between the patient and the doctor. My bias? Unless the fear is paralyzing, go for DBS surgery. The adjustability alone is invaluable.