RNS System NAUTILUS Study

Inclusion Criteria:

• Participant is age 12 and older.

• Participant is male or is a female of childbearing potential who is surgicallysterile, 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 inappropriate doses) with adequate monitoring of compliance and the effects oftreatment, as determined by the investigator.

• Participant is able to maintain an electronic diary alone or with the assistance ofa competent individual.

• Participant is able to attend clinic appointments in accordance with the studyschedule.

• Participant or parent(s) or legal representative have signed an IRB approved writteninformed consent/assent. The informed consent form or specific assent form, whererequired, will be signed and dated by minors.

• Participant is not currently implanted with an RNS Neurostimulator or NeuroPaceLeads.

• In the investigator's opinion, participant is able to tolerate a neurosurgicalprocedure.

• Participant with a confirmed diagnosis of idiopathic generalized epilepsyexperiencing primary generalized tonic-clonic seizures, with or without myoclonic orabsence seizures, consistent with the International League against Epilepsy RevisedClassification of Seizures (2017).

• Participant has had 2 or more generalized tonic-clonic seizures during the two monthretrospective baseline.

• Participant has had a routine electroencephalogram (EEG) within 2 years prior toenrollment with electroencephalographic features consistent with idiopathicgeneralized epilepsy; other concomitant anomalies must be explained by adequate pastmedical history.

• Participant has been on a stable antiseizure medication (ASM) regimen during the twomonth retrospective baseline and is willing to remain on a stable ASM regimen duringthe prospective Baseline and throughout the Effectiveness Evaluation Period, ifmedically possible; rescue benzodiazepine medications for acute seizure clusters arepermitted.

• Participant has undergone computed tomography (CT) or magnetic resonance imaging (MRI) within 10 years prior to enrollment that ruled out a progressive cause ofepilepsy or an abnormality likely to be associated with focal-onset seizures.

• Participant does not have a vagus nerve stimulator (VNS, LivaNova) or Participant'sVNS is OFF during the two month retrospective baseline and participant is willing tokeep the VNS off during the study.

Exclusion Criteria:

• Participant is pregnant.

• Participant is participating in a therapeutic investigational drug or other devicestudy.

• Participant is implanted with an electronic medical device that delivers electricalenergy to the brain.

• Participant requires procedures that are contraindicated based on current RNS Systemlabeling.

• Participant has been diagnosed with active psychosis, major depression or suicidalideation in the preceding year. Participants with post-ictal psychiatric symptomsneed not be excluded.

• In the opinion of the investigator, the participant has a clinically significant orunstable medical condition (including alcohol and/or drug abuse) or a progressivecentral 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 thepreceding year.

• Participant has experienced unprovoked status epilepticus in the preceding year.

• Participant is taking any anticoagulants.