By Rachel Levy
(Reuters) – Neuralink’s disclosure last week that tiny wires inside its first patient’s brain had become dislodged is a problem Elon Musk’s company has known about for years, according to five people familiar with the matter.
The company knew from animal tests carried out before its U.S. approval last year that the wires could retract, removing with them the sensitive electrodes that decode brain signals, three of the sources said. Neuralink considered the risk low enough that a redesign was not merited, the sources added.
Neuralink is testing its implant to give paralyzed patients the ability to use digital devices while thinking for themselves, a prospect that could help people with spinal cord injuries.
The company said last week that the implant’s tiny wires, which are thinner than a human hair, retracted from a patient’s brain in its first human test, resulting in fewer electrodes capable of measuring brain signals.
The signals are translated into actions, such as moving the mouse cursor on the computer screen. The company said it was able to restore the implant’s ability to monitor its patients’ brain signals by making changes that included modifying its algorithm to be more sensitive.
The sources declined to be identified, citing confidentiality agreements they signed with the company. Neuralink and its executives did not respond to calls and emails seeking comment.
The U.S. Food and Drug Administration was aware of the potential problem with the threads because the company shared animal test results as part of its request to begin human trials, one of the people said.
The FDA declined to comment on whether it was aware of the problem or its possible significance. The agency told Reuters it would continue to monitor the safety of patients enrolled in the Neuralink study.
If Neuralink continued testing without a redesign, it could face challenges if more wires were removed and its algorithm tuning proved insufficient, one of the sources said.
But redesigning topics comes with its own risks. Anchoring them to the brain, for example, could result in damage to brain tissue if the wires become dislodged or if the company needs to remove the device, two of the sources said.
The company has sought to design the wires so that their removal is seamless, so that the implant can be upgraded over time as technology improves, current and former employees say.
In January, Neuralink implanted the device into the brain of its first patient, Noland Arbaugh, who is paralyzed from the shoulders down due to a 2016 diving accident.
In the weeks after surgery, “several wires retracted from the brain,” Neuralink said in a blog update last week. The post made no mention of adverse health effects on Arbaugh and did not reveal how many of the device’s 64 wires had been removed or stopped collecting brain data.
So far, the device has allowed Arbaugh to play video games, browse the Internet and move the computer cursor on his laptop while thinking alone, according to company blog posts and videos. Neuralink says that shortly after surgery, Arbaugh surpassed the world record for the speed at which he can control a cursor with just his thoughts.
It’s common for medical device companies to troubleshoot different designs during animal testing and for problems to arise during clinical and animal testing, according to researchers and outside sources who have worked at Neuralink and other medical device companies.
Experts who have studied brain implants say the problem of wire movement can be difficult to solve, in part because of the mechanics of how the brain moves inside the skull.
Robert Gaunt, a neural engineer at the University of Pittsburgh, described the movement of the wires immediately after surgery as disappointing, but said it was not unexpected. “In the immediate days, weeks, months after an implant like this is probably the most vulnerable time,” he said.
ELEVATED PIG
In 2022, the FDA initially rejected Neuralink’s request to begin human trials and raised safety concerns about the threads, Reuters exclusively reported last year.
Neuralink conducted additional animal testing to address these concerns, and last year the FDA granted the company approval to begin human trials.
The company found that a subset of pigs implanted with its device developed a type of brain inflammation called granulomas, raising concerns among Neuralink researchers that the wires could be the cause, according to three sources familiar with the matter and records seen by Reuters.
Granulomas are an inflammatory tissue response that can form around a foreign object or an infection.
In at least one case, a pig developed a severe case of the disease. Company records reviewed by Reuters show the pig developed a fever and was panting after surgery. Neuralink researchers didn’t recognize the extent of the problem until they examined the pig’s brain post-mortem.
Inside Neuralink, researchers debated how to fix the problem and began a months-long investigation, sources familiar with the events said.
Ultimately, the company was unable to determine the cause of the granulomas, but concluded that the device and trapped wires were not to blame, one of the sources said.
(Reporting by Rachael Levy and Marisa Taylor in Washington; Editing by Greg Roumeliotis and Bill Berkrot)
