Research reveals cause of ‘freezing’ gait in Parkinson’s disease

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By Dennis Thompson
Health Day Reporter

MONDAY, September 12, 2022 (HealthDay News) — Researchers believe they have discovered why Parkinson’s disease causes a person’s limbs to become so stiff they can sometimes feel frozen.

Using a robotic chair equipped with sensors, a research team has linked leg muscle activation in Parkinson’s patients to a brain region called the subthalamic nucleus.

This oval-shaped brain area is involved in regulating movement, and data from the chair shows it controls the start, finish and magnitude of a person’s leg movements, according to a study published Sept. 7 Science Translational Medicine .

“Our results helped reveal marked changes in brain activity associated with leg movements,” said lead researcher Eduardo Martin Moraud, a junior principal investigator at the University of Lausanne in Switzerland.

“We were able to confirm that the same modulations underlie the encoding of gait states – for example, switching between standing, walking, turning, avoiding obstacles or climbing stairs – and walking deficits such as gait freezing,” Moraud said.

Parkinson’s disease is a degenerative disorder of the nervous system that primarily affects the motor functions of the body.

According to the Parkinson Foundation, people with Parkinson’s have trouble regulating the size and speed of their movements. They have trouble starting and stopping movements, connecting different movements to complete a task like standing up, or finishing one movement before beginning the next.

The subthalamic nucleus is part of the basal ganglia, a network of brain structures known to control several aspects of the body’s motor system, said Dr. James Liao, a Cleveland Clinic neurologist who reviewed the results.

“This study is the first to show convincingly that the basal ganglia control the power of leg movements,” Liao said. “The implication is that this links basal ganglia dysfunction to the shuffling gait deficit of Parkinson’s disease.”

To study the effects of Parkinson’s on walking, researchers built a robotic chair in which a person could either voluntarily extend their leg from the knee or the chair could do it for them.

The researchers recruited 18 Parkinson’s patients with severe motor fluctuations and problems with their gait and balance. Each patient was implanted with electrodes that could trace electrical signals from their subthalamic nucleus and also provide deep brain stimulation to that brain region.

Impulses from the subthalamic nucleus were monitored while the patients were using the chair and later when they were standing and walking.

“The fact that all of these aspects of walking are encoded in this brain region leads us to believe that it contributes to walking function and disorder, making it an interesting region for therapies and/or for predicting problems before they occur,” said Moraud. “We could use this understanding to develop real-time decoding algorithms that can predict these aspects of walking in real time, using only brain signals.”

In fact, the researchers have developed several computer algorithms that distinguish the brain signals of a regular step from those that occur in patients with walking disorders. The team was also able to identify episodes of freezing in patients when they performed short walk tests.

“The authors showed that gait freezing phases can be predicted from recorded neural activity,” Liao said. “Accurate predictions will make it possible to develop algorithms that change [deep brain stimulation] Patterns of behavior in response to periods of gait freezing that shorten or even eliminate freezing episodes.”

Moraud said these results could help inform future technologies aimed at improving the mobility of Parkinson’s patients.

“There are high hopes that the next generation of deep brain stimulation therapies that operate in a closed loop – meaning they deliver electrical stimulation in an intelligent and precise way based on feedback of what each patient needs – will be better can help alleviate gait and balance disorders,” Moraud said.

“However, closed-loop protocols depend on signals that can help control stimulation delivery in real time. Our results open up such possibilities,” he added.

dr Michael Okun, National Medical Advisor to the Parkinson’s Foundation, agreed.

“Understanding the brain networks underlying walking in Parkinson’s disease will be important for future therapeutic development,” Okun said. “The key question for this research team is whether the information collected is sufficient to power a neuroprosthetic system to improve walking ability in Parkinson’s.”

More information

The Parkinson Foundation has more about walking and movement difficulties associated with Parkinson’s.

SOURCES: Eduardo Martin Moraud, PhD, Junior Principal Investigator, University of Lausanne, Switzerland; James Liao, MD, neurologist, Cleveland Clinic; Michael Okun, MD, National Medical Advisor, Parkinson’s Foundation, New York City; Science Translational MedicineSeptember 7, 2022



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