Parkinson’s disease is a neurodegenerative disorder that makes it difficult for people to regulate their voluntary movements. Parkinson’s affects around 500,000 Americans, causing symptoms like stiffness, slowness of movement, and a stooped posture. For this reason, how a patient walks, referred to as their gait, is one of the primary ways doctors determine the quality of life for people with Parkinson’s disease. Although doctors have developed a variety of treatments for Parkinson’s, they’ve found few of these treatments help patients walk.
Scientists discovered that gait problems in patients with Parkinson’s are connected to their overactive brains. This overactivity is caused by a brain wave pattern, known as the beta-band, in a specific area of the brain that regulates movement, known as the subthalamic nucleus, or STN. Researchers have developed treatments that regulate activity in the STN, but they don’t know if changing the associated brain wave patterns would help patients walk more easily.
Researchers in the past have shown that applying electrical stimulation to the skin at different locations on a patient can stimulate a nerve that regulates muscle tone and other bodily functions, known as the vagus nerve. Scientists from Italy and the UK recently explored whether a form of this electrical stimulation, called transauricular vagus nerve stimulation or taVNS, could help Parkinson’s patients’ gait.
To conduct taVNS, the researchers applied an electrode to the outer ear of the Parkinson’s patients to stimulate the vagus nerve. The scientists had 2 primary questions: does taVNS reduce the activity of STN beta-band waves, and does this reduced activity allow patients with Parkinson’s to walk more easily?
The researchers enrolled 10 patients with Parkinson’s disease in the study. Each patient was being treated with another type of electrical stimulation to the STN. They asked the participants to stop taking any traditional Parkinson’s medication the night before the taVNS test and turned off their electrical stimulation 1 hour before the test.
During the taVNS test, the scientists applied 2 types of stimulation to each patient: one stimulated the vagus nerve through the ear, and one stimulated a different area that didn’t affect the brain, which they referred to as an imitation stimulation. They completed each type of simulation on the patients 4 times for 2 minutes, with 1 minute in between.
The researchers also measured the patients’ unconscious side-to-side movement while walking, or sways, the time it took them to turn around mid-test, or rotation time, their total steps, their step variability, their total walking time, and their walking speed, to compare the effects of the real and imitation treatments on the patients. Finally, they physically assessed each patient’s quality of life using the Unified Parkinson’s Disease Rating Scale part III.
The scientists found that the patients’ STN beta-band waves were 7% weaker on the right side during taVNS than during the imitation stimulation. They also found that taVNS improved the patients’ step variability, total walking time, and walking speed. The researchers also used a statistical test to show that participants with lower activity in their STN beta-band brain wave pattern walked faster. However, they found no significant improvements in the patients’ quality of life, based on their rating scale scores.
The researchers concluded that taVNS can help Parkinson’s patients walk faster, possibly by altering their STN beta-band brain waves. They also pointed out that taVNS is a non-invasive treatment, meaning that it does not require surgery or implantation into the body, making it much more affordable than invasive treatments. The scientists acknowledged that their study was small, and emphasized that future researchers should run tests with a larger group of patients to further determine how STN beta-band waves are related to gait in Parkinson’s disease.
