Parkinson's: Ultrasound treatment can improve motor symptoms

  • A recent study introduces a new, noninvasive means of using focused ultrasound to reduce the symptoms of Parkinson’s disease.
  • The technique involves destroying a small neuron cluster to interrupt the neuronal network that produces uncontrolled movement and motor impairment.
  • Compared to study participants receiving a sham treatment, twice the number of individuals receiving the new treatment experienced an improvement in their symptoms that lasted at least a year for many.

A new study presents a novel, noninvasive method for reducing involuntary movements, or dyskinesia, and motor impairment in people receiving treatment for Parkinson’s disease. The new method uses focused ultrasound.

At 3 months after undergoing the incisionless technique, twice as many people experienced an improvement in dyskinesia and motor impairment compared to study participants who received a sham, or placebo, treatment.

The improvements lasted up to 1 year in 77% of those who responded to the treatment.

People who undergo the focused ultrasound treatment can go home the same day.

The researchers reported infrequent adverse effects, including gait problems, speech difficulties, and visual disturbance. More serious adverse events occurred in the group that received the treatment than in the placebo group.

The study appears in The New England Journal of Medicine.

Dopamine and L-DOPA

Parkinson’s disease is the result of low levels of the neurotransmitter dopamine in the brain’s substantia nigra due to a loss of dopamine-producing neurons.

The leading theory is that there is a failure of autophagy, the brain’s housekeeping system, allowing an accumulation of debris that interferes with brain function.

“Dopamine synchronizes different areas of the brain so that they’re speaking to each other at the same frequency,” Dr. Jean-Philippe Langevin, director of the Restorative Neurosurgery and Deep Brain Stimulation Program at the Pacific Neuroscience Institute, who was not involved in the study, explained to Medical News Today.

“Imagine all these regions of the brain trying to communicate like a walkie-talkie or a phone, and then the frequency at which they’re [attempting to communicate] is off,” said Dr. Langevin. This leads to rigidity, hesitancy, and tremor, and movements cease to be fluid.

Without dopamine, Dr. Langevin explained, “a lot of noise” is introduced into the brain’s motor system, responsible for controlling movement. This “noise” is literal electrical noise that researchers can detect. There is now evidence that certain neuronal frequencies actually increase with Parkinson’s.

The most common treatment for the disease is levodopa, or L-DOPA, which restores dopamine to the brain.

For many individuals, however, the dyskinesia and motor impairment they experience are actually adverse effects of L-DOPA treatment.

The effectiveness of the medication also weakens over time.

How the new treatment works

The new technique assessed in the study is based on an existing treatment for essential tremor approved in 2016.

Focused ultrasound treatment ablates, or removes, a small cluster of neurons in the globus pallidus region of the brain. Ablation destroys the tissue by scarring it.

Study co-author Dr. Howard M. Eisenberg, professor of neurosurgery at the University of Maryland Medical System, explained to MNT how a little over 1,000 beams of sound energy reach and ablate the target tissue:

“Sound can be focused just like light. As a kid, let’s say you had a magnifying glass. You could focus the sun on a piece of paper, and you get a little dot of light focus, and that turned into heat, and you could burn a hole on the paper. We can do the same thing with sound.”

When the beams are focused and the energy is high enough, “you can burn a little hole in the brain” precisely at the focal point without damaging surrounding tissue, he told us.

“Essentially, that’s how it works: Back to the future, like ablation that was done years ago [for essential tremor], but using other technology,” said Dr. Eisenberg.

The ablated neurons are not necessarily the ones causing the dyskinesia and motor impairment, Dr. Eisenberg explained. Rather, he noted, “it’s a system of targets that are interconnected nuclei, and you’re interrupting that system.”

‘Reasons to be excited’

“There are reasons to be excited,” said Dr. Langevin, if the treatment allows Parkinson’s patients to reduce their L-DOPA medication.

Based on previous experience with essential tremor ablation, we may expect improvements in about 80% of patients, and they may persist at least for 5 years, according to Dr. Eisenberg.

Not everyone in the study experienced benefits following this treatment, however. Dr. Eisenberg suggested that a small number of participants may have skulls that are not as good at conducting acoustic energy.

That is because the skull is not a single piece of bone, but rather two hard layers of bone with a softer layer in-between, “like an Oreo cookie,” he explained.

Focused ultrasound vs. DBS

Dr. Eisenberg noted that ablation for essential tremor is viewed as less effective than deep brain stimulation (DBS). With DBS, tissue is not destroyed, but rather stimulated. DBS is also available for Parkinson’s dyskinesia and motor impairment.

However, DBS requires making one or more small openings in the skull into which a wire is inserted and guided to the target area in the brain. The wire is then connected to a small neurostimulator implanted in the chest.

Of those who would choose focused ultrasound instead, said Dr. Eisenberg, “[t]hey won’t consider it even though we always explain that deep brain stimulation has advantages over focused ultrasound. So, it’s good for those patients who just don’t want deep brain stimulation, which you can understand.”

The benefits offered by the new focused ultrasound technique are nonetheless powerful enough to be life-changing, he said.

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