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Interim Safety Profile From the Feasibility Study of the BrainGate Neural Interface System

Key findings

  • The neurosurgically placed BrainGate Neural Interface System is designed to transmit information directly from the cerebral cortex to assistive technology for people with paralysis
  • Massachusetts General Hospital researchers have helped to lead a seven-center U.S. consortium that conducted an initial feasibility trial of the BrainGate system between 2004 and 2009 and are directing the ongoing feasibility trial
  • Of 14 participants, 12 had no adverse event requiring device explantation, resulting in death or resulting in permanently increased disability over the one-year post-implantation period (two with amyotrophic lateral sclerosis died from their underlying disease within one year)
  • Eight participants used the investigational BrainGate system safely for more than two years and two for more than five years
  • There were 68 device-related adverse events, including six device-related serious adverse events, but none resulted in withdrawal from the trial, a need to explant the device or inability to continue participating in research sessions

Many people with paralysis have cortical substrates of motor activity, speech, and cognition that are intact but functionally disconnected from the nerves and muscles that enable movement and communication. Brain–computer interfaces transmit information directly from the cerebral cortex to assistive technology.

Investigators at Massachusetts General Hospital are part of a consortium studying the safety of the BrainGate Neural Interface System, a microelectrode array implanted in the primary motor cortex with a percutaneous component. In Neurology, they report favorable safety data from 12,203 participant-days of experience.

The authors are Daniel B. Rubin, MD, PhD, a critical care neurologist in the Department of Neurology, Ziv M. Williams, MD, a neurosurgeon in the Department of Neurosurgery, Sydney Cash, MD, PhD, co-director of the Center for Neurotechnology and Neurorecovery, and Leigh R. Hochberg, MD, PhD, a neurologist in the Division of Neurocritical Care and McCance Center for Brain Health, and co-director of the Center for Neurotechnology and Neurorecovery, and colleagues.


The BrainGate consortium is conducting a prospective, nonrandomized feasibility trial. Fourteen adults ages 18 to 75 years with quadriparesis caused by spinal cord injury, brainstem stroke, motor neuron disease, or muscular dystrophy have been recruited at seven U.S. centers:

  • Four enrolled in a first-generation BrainGate trial between 2004 and 2009
  • One transitional participant enrolled in the first-generation trial when it ended in 2009, then enrolled in a trial of the second-generation BrainGate and participated for another two years
  • 10 other people, including two participants still active, enrolled in the second-generation BrainGate trial; in 2013, the protocol changed so that two arrays are placed per participant instead of one

The median age at array implantation was 51 years (range, 24–66). The current analysis includes follow-up through December 2021. Twelve participants were enrolled for more than one year, of whom eight used BrainGate for more than two years and two for more than five years.

Primary Endpoint

All 12 participants enrolled for more than one year met the primary safety endpoint: no serious adverse event (SAE) requiring device explantation, resulting in death or permanently increased disability during the one-year post-implantation period.

The other two participants died of complications from amyotrophic lateral sclerosis before the one-year evaluation.

Adverse Events

There were 68 device-related AEs, including six SAEs classified as possibly, probably, or definitely device- or procedure-related. No AE resulted in death, withdrawal from the trial, a need to explant the device, or inability to continue participating in research sessions.

The most common device-related AE (35/68) was local skin reaction and/or sensitivity around the percutaneous pedestal. One participant required treatment for a skin infection around a pedestal site.


Two participants had seizures on postoperative day four. Both responded well to levetiracetam and continued in the trial without other neurologic AEs. Neither had received consistent postoperative seizure prophylaxis, and both had a history of traumatic brain injury that was believed to have increased their risk of seizures.

One participant experienced new-onset refractory status epilepticus after 18 months in the trial. All seizure activity was resolved by hospital day four, and the participant resumed participating in research sessions about four months later, continuing for another eight months.

Future Directions

An important goal of the BrainGate consortium is to develop a fully implantable system, reducing the infection concern presented by a percutaneous component and providing more acceptable cosmesis.

This trial continues to benefit from advances in machine learning/artificial intelligence and microprocessor technology, which have led to ongoing improvement in participant performance. The BrainGate trial is the longest-running and ongoing trial of an intracortical brain-computer interface, and its scientific success, along with this encouraging safety profile, has inspired the creation of numerous academic initiatives and startup companies to develop implanted brain-computer interfaces toward helping people with severe speech and motor impairment.

CAUTION: Investigational Device. Limited by Federal law to investigational use only.

Learn more about the Center for Neurotechnology and Neurorecovery

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