To demonstrate that the RNS System for thalamic stimulation is safe and effective as an adjunctive therapy for the reduction of primary generalized seizures in individuals 12 years of age or older who have drug-resistant idiopathic generalized epilepsy.

NeuroPace is sponsoring the NAUTILUS Study with the RNS System for thalamic stimulation as an adjunctive therapy for the treatment of generalized seizures in individuals 12 years of age or older who have drug-resistant idiopathic generalized epilepsy. The RNS System is currently approved by the FDA for use in patients 18 years and older with hard-to-treat partial-onset seizures. The same device will be used in the NAUTILUS Study.

The study is a prospective, multicenter, single-blind, randomized, sham stimulation controlled pivotal study and participants will be followed for two years after placement of the RNS System. The study will enroll a maximum of 100 participants within the United States to ensure that at least 80 participants are implanted with the RNS System.

The study design includes a two-month retrospective and one-month prospective baseline. All participants will have detection enabled at the time of implant. At one month post-implant, participants will be randomized 1:1 to Active or Sham stimulation. For those randomized to the Active group, stimulation will be enabled. Participants will be blinded to their own randomization status until the 2nd GTC occurs for that individual, they completed the 9-month Effectiveness Evaluation Period (12-months post-implant), or the 60th GTC-event occurs in the group, whichever occurs first. After that, patients will be unblinded and patients in the Sham group (responsive stimulation OFF) will have responsive stimulation enabled (responsive stimulation ON).

Inclusion Criteria:

• Participant is age 12 and older.
• Participant is male or is a female of childbearing potential who is surgically sterile, 2 years postmenopausal, or practices a reliable method of contraception (hormonal, barrier method or abstention).
• Participant failed treatment with a minimum of two antiseizure medications (used in appropriate doses) with adequate monitoring of compliance and the effects of treatment, as determined by the investigator.
• Participant is able to maintain an electronic diary alone or with the assistance of a competent individual.
• Participant is able to attend clinic appointments in accordance with the study schedule.
• Participant or parent(s) or legal representative have signed an IRB approved written informed consent/assent. The informed consent form or specific assent form, where required, will be signed and dated by minors.
• Participant is not currently implanted with an RNS Neurostimulator or NeuroPace Leads.
• In the investigator's opinion, participant is able to tolerate a neurosurgical procedure.
• Participant with a confirmed diagnosis of idiopathic generalized epilepsy experiencing primary generalized tonic-clonic seizures, with or without myoclonic or absence seizures, consistent with the International League against Epilepsy Revised Classification of Seizures (2017).
• Participant has had 2 or more generalized tonic-clonic seizures during the two month retrospective baseline.
• Participant has had a routine electroencephalogram (EEG) within 2 years prior to enrollment with electroencephalographic features consistent with idiopathic generalized epilepsy; other concomitant anomalies must be explained by adequate past medical history.
• Participant has been on a stable antiseizure medication (ASM) regimen during the two month retrospective baseline and is willing to remain on a stable ASM regimen during the prospective Baseline and throughout the Effectiveness Evaluation Period, if medically possible; rescue benzodiazepine medications for acute seizure clusters are permitted.
• Participant has undergone computed tomography (CT) or magnetic resonance imaging (MRI) within 10 years prior to enrollment that ruled out a progressive cause of epilepsy or an abnormality likely to be associated with focal-onset seizures.
• Participant does not have a vagus nerve stimulator (VNS, LivaNova) or Participant's VNS is OFF during the two month retrospective baseline and participant is willing to keep the VNS off during the study.

Exclusion Criteria:

• Participant is pregnant.
• Participant is participating in a therapeutic investigational drug or other device study.
• Participant is implanted with an electronic medical device that delivers electrical energy to the brain.
• Participant requires procedures that are contraindicated based on current RNS System labeling.
• Participant has been diagnosed with active psychosis, major depression or suicidal ideation in the preceding year. Participants with post-ictal psychiatric symptoms need not be excluded.
• In the opinion of the investigator, the participant has a clinically significant or unstable medical condition (including alcohol and/or drug abuse) or a progressive central nervous system disease.
• Participant has a history of partial-onset seizures or EEG findings within the past 2 years indicative of partial-onset or symptomatic generalized abnormalities.
• Participant has been diagnosed with psychogenic or non-epileptic seizures in the preceding year.
• Participant has experienced unprovoked status epilepticus in the preceding year.
• Participant is taking any anticoagulants.