Stentrode Device Allows 4 Paralyzed ALS Patients to Use Computers

Brain-computer interface system shows safety, feasibility in small clinical trial

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Synchron‘s Stentrode, an implantable brain-computer interface designed to allow people with amyotrophic lateral sclerosis (ALS) and other paralyzing conditions to control a computer using their thoughts, showed a positive safety profile in a small clinical trial.

The four people in the Australian study had ALS and severe paralysis, and they were able to use the device to carry out online activities like shopping and sending emails.

“This technology holds great promise for people with paralysis who want to maintain a level of independence. The Stentrode enables a form of motor restoration, with individuals able to use the switches to communicate and engage with their digital world,” Bruce Campbell, MD, a neurology professor at the University of Melbourne and trial investigator, said in a Synchron press release.

Full findings were detailed in the study, “Assessment of Safety of a Fully Implanted Endovascular Brain-Computer Interface for Severe Paralysis in 4 Patients,” published in JAMA Neurology. The work was funded by Synchron.

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Stentrode device enters brain via blood vessel in the neck

ALS and other conditions that make physical movement challenging can make it difficult to use technology like smartphones and computers. Brain-computer interfaces, or BCIs, are devices that aim to record electrical signals in the brain and translate them into signals that can be understood by a computer, allowing paralyzed patients to control digital tools using “just a thought.”

Most BCI devices developed to date require surgery to be implanted in the brain, an invasive approach that has limited their use. Stentrode, considered by the company as “similar to a stent,” is designed to allow easier implantation. The small, tube-like device is inserted through an incision into a blood vessel in the neck and snaked up to the brain, where it can record electrical signals.

“The device is designed to become incorporated into the wall of the blood vessel like a tattoo,” the company reported on a webpage.

The brain sensor is connected via a wire to a transmitter unit placed under the skin in the chest, which wirelessly transmits signals to a computer. It “operates with a commercial software on a laptop computer,” the researchers wrote.

In the brain, the sensor is placed over the motor cortex — a region that controls voluntary movement — to detect electrical impulses associated with attempted movement. These signals then are transformed into specific digital actions through a series of algorithms.

“Our view is that a motor neuroprosthesis should be safe and easy to use,” said Tom Oxley, MD, PhD, CEO and founder of Synchron. “Digital switches controlled by motor intent could translate into a meaningful restoration of motor capability for patients with paralysis and the return of things we take for granted, like texting loved ones or turning on a light.”

In the first clinical trial called SWITCH (NCT03834857), four adults with ALS and severe upper-limb paralysis were given the Stentrode device and followed for one year. All four patients identified as male and of European ancestry; their mean age was 61.

The study’s main goal was to assess the safety of the device. Results were positive, with no serious side effects related to the device reported in any of the patients. Some mild side effects occurred, such as headache or bruising at the site where the device is implanted, but all resolved in time without medical intervention.

3 patients started with computer tasks using device after one training session

Analyses also indicated that the Stentrode device did not interfere with blood flow or cause clotting problems. The device remained in the same stable position throughout the yearlong study, and electrical signals recorded by the device were consistently strong.

“We carefully conducted this first-in-human study with a primary focus on safety. The patients all tolerated the procedure well and were typically discharged home within 48 hours,” said Peter Mitchell, a study investigator at Royal Melbourne Hospital, where the trial took place.

In three patients, the Stentrode device was combined with eye-tracking technology: the person would use their eyes to move a cursor on a screen, and then use the Stentrode device to facilitate clicking. The fourth patient went without eye tracking, using a computer system that cycled through options that could be selected with the device.

Evaluations of feasibility generally supported the Stentrode’s use: the first patient was able to perform computer tasks at home after nine training sessions with the device, and the other three were performing tasks after one training session.

Patients used the system to complete tasks like emailing, texting, shopping, managing their personal finances, and communicating things like needs with caregivers. They typed at an average rate of 16.6 characters per minute using the system, and 97.2% of what they typed was correct in texts.

“The perceived benefit was patient-specific: increased communication speed for one patient … communication with friends and family overseas for another patient, and the ability to organize a music collection for another patient,” the researchers wrote.

Each “expressed satisfaction and fulfillment from regaining the ability to perform everyday tasks on the computer,” the team added.

The SWITCH study “of an endovascular BCI was completed with no device-related serious adverse events or persistent neurological deficits,” the scientists concluded. “Safety and feasibility data from the first in-human study indicate that it is possible to record neural signals from a blood vessel, and the favorable safety profile could promote wider and more rapid translation of BCI to people with paralysis.”

Noting this was a small and relatively short trial, they stressed that further research is needed to confirm safety and optimize the functionality of the Stentrode BCI device.