Synchron Pauses Brain Implant Trial Enrollment Over Faulty Lead
The brain-computer interface startup halted new enrollment in the US, Australia and Canada after a cable in its second-generation Stentrode underperformed.
Synchron, a Brooklyn-based startup developing a brain-computer interface that is threaded into the brain through a blood vessel, has stopped enrolling new patients in clinical trials of its latest implant after finding a performance problem with a key component, WIRED reported. The company says it will upgrade the hardware before recruitment resumes, a setback that could delay the late-stage study it needs before it can ask US regulators to approve the device.
What happened
According to WIRED, Synchron told the magazine it had voluntarily paused enrollment after identifying an issue with the lead, the cable that carries signals from its Stentrode implant to electronics placed under the patient’s skin. The company said the problem does not involve the Stentrode itself and that it has not identified any device-related safety issues.
The pause affects a multisite US trial of Synchron’s second-generation system, which began earlier this spring, as well as sister sites in Australia and Canada. Some participants have already received the new device. People familiar with the trials told WIRED that the system was “not working as intended” and had failed to perform as expected in the first participants. WIRED said two of the five US trial sites it contacted confirmed they had stopped enrolling, according to a summary of the report by the tech news site Startup Fortune.
Accounts of the scope differ slightly. Some outlets that republished or summarized the news, including the Indian news site IndiaVision, described the company as having temporarily suspended its ongoing clinical trials. The company’s own statement, as quoted by WIRED, refers specifically to a pause in enrollment, meaning patients already implanted are not described as being removed from the studies. No date has been set for recruitment to restart.
Synchron said it has moved design and manufacturing of the lead in-house and has pledged lifelong support for people who already have the implant.
Restructuring and a new device
The trial pause comes as the company reorganizes. WIRED reported that Synchron is cutting jobs and shrinking its footprint in New York while building a team in San Diego to work on an entirely new device. The company has not publicly detailed how many positions are affected.
The second-generation Stentrode differs significantly from the original. The first version relied on an external wire that rested on the user’s chest, while the new one is fully wireless, connects over Bluetooth and uses fewer electrodes.
Why it matters
Synchron is one of the most closely watched companies in the race to build brain-computer interfaces, devices that read neural signals and translate them into commands for computers and other machines. Its approach is meant to be less invasive than rivals such as Neuralink, the company founded by Elon Musk, whose implant is placed directly in brain tissue through surgery.
The Stentrode is a small, stent-like mesh tube inserted into the jugular vein at the base of the neck and guided by catheter to rest against the motor cortex, the part of the brain that controls movement. Because it sits inside a blood vessel, it does not require open brain surgery.
Earlier results were encouraging. Ten volunteers in the United States and Australia used the first-generation device to send texts and emails, browse the web, bank and shop online, and control an Amazon Alexa, an iPad and an Apple Vision Pro headset without using their hands or voice, WIRED reported. In Synchron’s COMMAND study, an early US feasibility trial whose results were announced in September 2024, all six patients met the main safety goal of no device-related serious adverse events over 12 months, according to Tech Times.
Synchron has also forged ties with major tech companies. Tech Times reported that it began running neural decoding software on Nvidia’s Holoscan platform in January 2025, and said in May 2025 that it would be the first brain-computer interface company with native support for Apple’s protocol for controlling devices with such implants. Startup Fortune noted it was unclear how the pause would affect that work.
What comes next
The Stentrode received Breakthrough Device designation from the US Food and Drug Administration in August 2020, a status meant to speed review of promising medical technologies. But the company still needs a successful pivotal trial, the large, late-stage study regulators rely on, before it can apply for premarket approval. Synchron had been preparing that trial for 2026, Tech Times reported.
In November 2025, Synchron announced a $200 million Series D funding round led by Double Point Ventures to pay for the pivotal trial and preparations for a commercial launch. Other backers include ARCH Ventures, Khosla Ventures and Bezos Expeditions, according to Tech Times.
Startup Fortune noted that the hardware changes could push back that pivotal study, and that data collected from the current system may not carry over cleanly to an upgraded design. Key open questions include:
- When enrollment will resume and at how many sites.
- Whether the upgraded lead will require new regulatory review before trials restart.
- How the separate, all-new device being developed in San Diego fits into the company’s timeline.
