RNS System NAUTILUS Study

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 electroence…