Brain implants that stop seizures before they spread

How far are brain implants that respond to seizure activity from routine epilepsy care, and from use in other conditions?

Implants that sense abnormal brain activity and stimulate in response are approved in the US for a narrow group of adults with focal epilepsy. The NeuroPace RNS System is used at specialist US epilepsy centres. Studies report median seizure reductions over several years, but results vary: in a three-year post-approval study, 41% of people had a reduction of at least 90%. A randomised trial in generalised epilepsy missed its main effectiveness endpoint. In July 2026 NeuroPace reported that the FDA had said the expansion application was not approvable in its current form. Evidence for other conditions is early.

AI illustration · Illustrative scene, not a photograph of the specific device or experiment.
WHERE WE AREScaling up

Nearly here. It works and is being scaled up.

The RNS System has FDA premarket approval for adults with focal epilepsy and is in clinical use at US epilepsy centres. The company reported RNS System revenue of $22.5 million for Q2 2026, up 21.3% on the year. It is not yet widespread: use is concentrated in specialist centres, the approved group is narrow, and the generalised epilepsy indication has not been granted. Approvals outside the United States were not checked for this profile.

The tech tree

Everything recorded on Vrulum that this future needs, oldest foundations at the top and the goal at the bottom. Lines show what each step requires.

What it takes: Brain implants that stop seizures before they spread Unlocked Being researched Locked
  1. 1998Adaptive deep brain stimulationCommercial Unlocked.
  2. 2010Closed-loop brain stimulation for epilepsyCommercial Unlocked.
  1. 2013FDA approval for adults with focal epilepsyDone Unlocked.
  2. 2014Randomised sham-controlled pivotal trialDone Unlocked.
  3. 2015Long-term cohort follow-upDone Unlocked.
  4. 2024Adaptive deep brain stimulation with peer-reviewed efficacy in epilepsyNot started Locked.
  5. 2026Three-year post-approval studyDone Unlocked.
  6. 2026Randomised trial in idiopathic generalised epilepsyDone Unlocked.
  7. 2026Approval for generalised epilepsyIn progress Being researched.
  8. Date not recordedAccess and cost evidenceIn progress Being researched.
  1. GoalBrain implants that stop seizures before they spreadGoalRequires: Closed-loop brain stimulation for epilepsy, Adaptive deep brain stimulation, FDA approval for adults with focal epilepsy, Randomised sham-controlled pivotal trial, Three-year post-approval study, Long-term cohort follow-up, Randomised trial in idiopathic generalised epilepsy, Approval for generalised epilepsy, Access and cost evidence, Adaptive deep brain stimulation with peer-reviewed efficacy in epilepsy. Locked.

The road so far

5 of 8 steps done, 2 in progress.

  1. Done · Nov 2013FDA approval for adults with focal epilepsy

    The FDA granted premarket approval in November 2013. The release gives no day and states the device was evaluated in patients averaging three or more disabling seizures a month. A 2020 company release gives the current indication as adjunctive therapy for adults with refractory, focal onset seizures with no more than two epileptogenic foci. [12][13]

  2. Done · 22 Feb 2014Randomised sham-controlled pivotal trial

    In the double-blind trial of 191 randomised adults, seizure reduction was greater with active stimulation than with sham at the end of the blinded period. Serious adverse events did not differ between the two groups. [1]

  3. Done · 24 Apr 2026Three-year post-approval study

    Of 324 people implanted across 32 US centres, the median seizure reduction was 62% at six months and 82% at three years. At three years, 41% had a reduction of at least 90%. The abstract describes an open-label study with no concurrent control group. [3]

  4. Done · 23 Jan 2015Long-term cohort follow-up

    230 participants from the open-label and randomised studies continued into long-term follow-up, with a mean of 5.4 years. Median seizure reduction ranged from 48% to 66% across post-implant years three to six. The most common serious device-related events were implant-site infection (9.0%) and neurostimulator explantation (4.7%). The abstract checked does not give a SUDEP rate. [2]

  5. Done · 3 Jun 2026Randomised trial in idiopathic generalised epilepsy

    The NAUTILUS trial randomised 87 implanted adults with drug-resistant idiopathic generalised epilepsy to active stimulation (44) or sham (43) at 23 US centres. The safety endpoint was met, with serious adverse device effects in 6.9%. The prespecified effectiveness endpoint, time to second generalised tonic-clonic seizure, was not statistically significant. A post hoc analysis found a 61% reduction in the active group against 49% in the sham group (p = 0.030). At 18 months the median reduction in tonic-clonic seizures was 76.8%, and 40% were free of them. [4][6]

  6. In progress · 28 Jul 2026Approval for generalised epilepsy

    NeuroPace filed a PMA supplement in December 2025 to extend the label to drug-resistant idiopathic generalised epilepsy. On 28 July 2026 the company reported that the FDA said the supplement was not approvable in its current form and asked for more clinical evidence, including from NAUTILUS. The company said a Submission Issue Request meeting is planned. No approval date was given. [8][7]

  7. In progressAccess and cost evidence

    A US public-payer decision model estimated $28,825 to $46,596 per QALY for RNS therapy added to medicines, compared with medicines alone. That is a modelled result, with conclusions dependent on utility estimates and the willingness-to-pay threshold. A US claims study found mean 12-month all-cause costs were 50% lower for vagus nerve stimulation than for RNS or deep brain stimulation combined. The authors note that the database lacked seizure frequency data. [10][11]

  8. Not started · 19 Aug 2024Adaptive deep brain stimulation with peer-reviewed efficacy in epilepsy

    No peer-reviewed seizure-reduction results for adaptive deep brain stimulation in epilepsy were found in the sources checked. The closest evidence is in Parkinson's disease: a blinded randomised cross-over pilot in four people, which the authors describe as showing improved motor symptoms and quality of life with adaptive stimulation, with larger trials needed. [5]

Why it matters

Some people with epilepsy keep having seizures on medicine, and each seizure carries a risk of injury and disrupts daily life. A device that responds to a seizure pattern, rather than dosing on a timetable, could offer a non-drug option. Its reach depends on surgery, specialist centres, cost, and proof in more types of epilepsy and other conditions.

What stands in the way

  • NeuroPace reports that the FDA said the generalised epilepsy supplement is not approvable in its current form and has asked for more clinical evidence, so that route is blocked for now.
  • The prespecified effectiveness endpoint in the NAUTILUS trial was not met, and its positive finding came from a post hoc analysis.
  • The approved group is narrow, and use is concentrated in specialist centres, so routine use across general epilepsy care has not been shown.
  • Benefit varies widely between people. In the three-year post-approval study, 59% did not reach a 90% reduction, so most people still had some seizures.
  • Surgery carries risks: the long-term cohort reported implant-site infection in 9.0% and neurostimulator explantation in 4.7%.
  • Cost evidence is thin: the modelled cost per QALY depends on assumptions, and a claims study found higher costs than for vagus nerve stimulation.
  • Several key studies report authors affiliated with the device maker, and the NAUTILUS results were first released by the company, so independent replication is limited.

Signals to watch

  • An FDA decision on the generalised epilepsy supplement after the Submission Issue Request meeting.
  • Peer-reviewed analysis of NAUTILUS led by authors outside NeuroPace, including any longer follow-up.
  • Closed-loop stimulation trials for epilepsy run by independent groups, not the device maker.
  • Peer-reviewed seizure-reduction results for adaptive deep brain stimulation in epilepsy.
  • Approvals or reimbursement decisions for these devices outside the United States, and published cost data from payers.

Sources

  1. peer reviewed paper
    Two-year seizure reduction in adults with medically intractable partial onset epilepsy treated with responsive neurostimulation: Final results of the RNS System Pivotal trial
    Christianne N. Heck, Martha J. Morrell. Epilepsia, 22 Feb 2014.
  2. peer reviewed paper
    Long-term treatment with responsive brain stimulation in adults with refractory partial seizures
    G. K. Bergey, M. J. Morrell, E. M. Mizrahi. Neurology, 23 Jan 2015.
  3. peer reviewed paper
    Postapproval Study for Brain-Responsive Neurostimulation for Drug-Resistant Focal Epilepsy: Three-Year Efficacy and Interim Safety Results
    D. Eliashiv, V. R. Rao, B. C. Jobst. Neurology, 24 Apr 2026.
  4. peer reviewed paper
    Responsive stimulation of the thalamus for idiopathic generalized epilepsy: Results of the randomized controlled NAUTILUS trial through 18 months
    U. Uysal, M. J. Morrell. Epilepsia, 3 Jun 2026.
  5. peer reviewed paper
    Chronic adaptive deep brain stimulation versus conventional stimulation in Parkinson's disease: a blinded randomized feasibility trial
    Carina R. Oehrn, Stephanie Cernera, Lauren H. Hammer. Nature Medicine, 19 Aug 2024.
  6. company announcement
    NAUTILUS Study: RNS System for Idiopathic Generalized Epilepsy
    NeuroPace, 3 Jun 2026.
  7. company announcement
    NeuroPace Announces Positive 18-Month NAUTILUS Trial Results in Idiopathic Generalized Epilepsy
    NeuroPace, 8 Dec 2025.
  8. company announcement
    NeuroPace Receives FDA Guidance on PMA Supplement for Indication Expansion into Idiopathic Generalized Epilepsy
    NeuroPace, 28 Jul 2026.
  9. company announcement
    NeuroPace Reports Second Quarter 2026 Financial Results and Raises 2026 Revenue Guidance
    NeuroPace (SEC Form 8-K, exhibit 99.1), 11 Aug 2026.
  10. peer reviewed paper
    Cost-effectiveness analysis of responsive neurostimulation for drug-resistant focal onset epilepsy
    B. E. Youngerman, U. V. Mahajan, T. G. Dyster. Epilepsia, 29 Aug 2021.
  11. peer reviewed paper
    Comparison of utilization and cost of healthcare services and pharmacotherapy following implantation of vagus nerve stimulation vs. responsive neurostimulation or deep brain stimulation for the treatment of drug-resistant epilepsy: analyses of a large United States healthcare claims database
    T. Vincent, Q. Li, L. Zhang. Journal of Medical Economics, 2022.
  12. news
    Brain stimulation device demonstrates safety, seizure reduction
    ScienceDaily (American Epilepsy Society release), 10 Dec 2013.
  13. company announcement
    NeuroPace RNS System Receives FDA Approval for MRI Labeling, Allowing Thousands More Patients to Benefit from Personalized, Data-Driven Epilepsy Treatment
    NeuroPace, 9 Mar 2020.

Last reviewed 21 Oct 2026.