A novel endovascular brain-computer interface (BCI) is safe and effective, allowing paralyzed patients to use their thoughts to perform daily tasks, results of a small, first-in-human study show.
A potential life changer for patients with amyotrophic lateral sclerosis (ALS), the minimally invasive device enables patients to carry out important activities of daily living.
“Our participants are able to use the device to perform tasks like sending email, texting loved ones and caregivers, browsing the web, and doing personal finances such as online banking,” study investigator Douglas J. Weber, PhD, professor of mechanical engineering and neuroscience, Carnegie Mellon University, Pittsburgh, Pennsylvania, told a press briefing.
The findings will be presented at the American Academy of Neurology (AAN) 2022 Annual Meeting, which begins Saturday and runs through April 7. The meeting will also be held virtually from April 24-26.
Minimally Invasive
ALS, also known as Lou Gehrig’s disease, is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord. Patients with ALS eventually lose the ability to control muscle movement, often leading to total paralysis.
“Extending the period in which patients are able to communicate with loved ones and caregivers could provide a very meaningful benefit to patients with ALS,” said Weber.
BCIs measure and translate brain signals, with some functioning as motor neuro-prostheses (MNPs). These devices provide direct communication between the brain and an external device by recording and decoding signals from the precentral gyrus as the result of movement intention.
“The technology has potential to empower the more than five million people in the US who are severely paralyzed to once again perform important activities of daily living independently,” said Weber.
Until now, MNPs required surgery to remove a portion of the skull and place electrodes on to the brain. However, the new minimally invasive MNP reaches the brain by vascular access, dispensing with the need for a craniotomy.
“The BCI device used in our study is unique in that it does not require invasive open surgery to implant,” said Weber. “Instead this is an endovascular BCI”.
Using a catheter, surgeons feed the BCI through one of two jugular veins in the neck. They position an array of 16 sensors or electrodes on a stent-like scaffold that deploys against the walls of the superior sagittal sinus.
No Adverse Events
Describing the device, Weber said the electrodes or sensing elements are tiny and the body of the stent, which serves as a scaffold to support the electrodes, resembles a standard endovascular stent.
“It’s very small at the time of delivery because it’s held within the body of a catheter, but then when deployed it expands to contact the wall of the vein.”
The device transmits brain signals from the motor cortex to an electronics unit, located in a subcutaneous pocket that decodes movement signals. The machine-learning decoder is programmed as follows: When a trainer asked participants to attempt certain movements, like tapping their foot or extending their knee, the decoder analyzes nerve cell signals from those movement attempts. The decoder is able to translate movement signals into computer navigation.
The study included four patients with ALS who were paralyzed because of the disease and were trained to use the device.
A key safety endpoint was device-related serious adverse events resulting in death or increased disability during the post-implant evaluation period. Results showed all four participants successfully completed the 12-month follow-up with no serious adverse events.
Researchers also assessed target vessel patency and incidence of device migration at 3 and 12 months. Postoperative imaging showed that in all participants, the blood vessel that held the implanted device remained open and stayed in place.
Addressing the potential for blood clots, Weber said that so far there has been no sign of clotting or vascular occlusion.
“The device itself integrates well into the walls of the blood vessel over time,” he said. “Within the acute period after implantation, there’s time where the device is exposed to the blood stream, but once it becomes encapsulated and fully integrated into the blood vessel wall, the risks of thrombosis diminish.”
Greater Independence
Researchers also recorded signal fidelity and stability over 12 months and use of the BCI to perform routine tasks. All participants learned to use the MNP with eye tracking for computer use. Eye tracking technology helps a computer determine what a person is looking at.
Using the system, patients were able to complete tasks without help. These included text messaging and managing finances. “Since the device is fully implanted and easy for patients to use, they can use the technology independently and in their own home,” said Weber.
A potentially life-changing device, the technology allowed one patient to write a book, (due out later this year) and another patient to maintain communication despite losing his ability to speak, the study’s lead author, Bruce Campbell, MBBS, PhD, professor of neurology, Royal Melbourne Hospital, University of Melbourne, Australia, told Medscape Medical News.
“In addition to providing patients with communicative capabilities not possible as a result of their disease, it is our goal to enable patients to be more independently involved in their care going forward, by enabling effective and faster communication directly with their caregiver and physician,” said Campbell.
Although the study started with patients with ALS, those paralyzed from other causes, such as an upper spinal cord injury or brain-stem stroke, could also benefit from this technology, said Weber.
In addition, the technology could be expanded to broaden brain communication capabilities potentially to include robotic limbs, he said.
There’s even the potential to use this minimally invasive brain interface technology to deliver therapies like deep brain stimulation (DBS), which Weber noted is a growing field.
“It’s [the] early days, but it’s a very exciting new direction for brain interface technology,” said Weber.
Researchers are now recruiting patients for the first US-based feasibility trial of the device that will be funded by the NIH, said Weber. A limitation of the research was the study’s small size.
Advancing the Field
Reached for a comment, Kevin C. Davis, an MD and PhD student in the Department of Biomedical Engineering, University of Miami Miller School of Medicine, Miami, Florida, said this new work moves the field forward in an important way.
Davis and colleagues have shown the effectiveness of another technology used to overcome paralysis — a small portable system that facilitates hand grasp of a patient with a spinal cord injury. He reported on this DBS-based BCI system at the American Association of Neurological Surgeons (AANS) 2021 Annual Meeting.
Developing effective BCIs, and motor neural prosthetics that avoid surgery as the team did in this new study, is “worth exploring,” Davis told Medscape Medical News.
However, although the device used in this new study avoids cranial surgery, “sole vascular access may limit the device’s ability to reach other areas of the brain more suitable for upper-limb motor prosthetics,” he said.
“Determining how much function such a device could provide to individuals with locked-in syndrome or paralysis will be important in determining its viability as an eventual clinical tool for patients.”
The study was supported by Synchron Inc, the maker of the device, the US Defense Advanced Research Projects Agency, the Office of Naval Research, the National Health and Medical Research Council of Australia, the Australian Federal Government Foundation, and the Motor Neuron Disease Research Institute of Australia.
American Academy of Neurology (AAN) 2021 Annual Meeting. April 2-7, 2022.
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