A research team at the Korea Institute of Science and Technology (KIST) has developed a wearable wireless low-intensity focused ultrasound brain stimulator that can treat brain nerves damaged by stroke.
Stroke is a serious disease that has a high mortality rate, and even if patients avoid death, it becomes difficult for them to move their body as the stroke can damage brain nerve cells by not supplying blood to the brain.
To treat such patients, healthcare companies have been developing various technologies, such as exercise therapy and cranial nerve stimulation, to rehabilitate the cranial nerves damaged by a stroke.
Among such technologies, the low-intensity focused ultrasound stimulation technology has high efficacy in treating stroke patients. It can activate or inhibit nerve cells by delivering mechanical energy to the desired location with high accuracy through ultrasound passing through the skull without surgery.
"To use this technology for rehabilitation of stroke patients in various environments, there was a need to develop an ultrasound machine that can be worn comfortably in everyday life," the team said. "However, existing ultrasonic brain stimulators were heavy and fixed, so they could only be used in experiments involving anesthetized or fixed animals."
To resolve such an issue, the team, led by Professor Kim Hyung-min at the university, developed a lightweight, wearable brain stimulator weighing about 20 grams that can wirelessly control low-intensity focused ultrasound waves. Afterward, the team used a stroke rat model and verified the device's rehabilitation efficacy by measuring exercise ability.
When the team applied ultrasound with a pressure of about 426 kPa to the area in charge of the mouse's movement, they confirmed significant improvement in the rat's exercise capacity after three days compared to the stroke model without ultrasound.
After a week of rehabilitation, the team confirmed that treated rats showed similar motor skills compared to normal rats.
"The study is significant as it has proven that non-invasive cranial nerve rehabilitation treatment using a wearable ultrasound device is possible in an era where the recent development of wearable brain stimulation technology is rapidly progressing," Professor Kim said.
To ensure the safety and effectiveness of disease treatment after stimulation, the research team plans to conduct additional follow-up studies to discover the molecular and cellular mechanisms of neuromodulation through ultrasound stimulation and optimize stimulation protocols, he added.
IEEE Transactions on Biomedical Engineering published the results of the study.