RNS System LGS Feasibility Study

Eligibility Criteria

• * Participant is 15 years of age or older for first cohort; 12 years of age or older for second cohort. Note that age requirements for eligibility differ by cohort, as follows: the age limit for Cohort 1 is 15 years of age and above and the age limit for Cohort 2 may decrease to 12 years, pending a DSMB letter of recommendation, based on review of interim data analysis and concurrence with NINDS.
• * Participant has medically intractable epilepsy defined as failure to achieve acceptable seizure control without unacceptable medication related side effects despite trials of 2 or more antiseizure medications.
• * Participant had an average of ≥ 5 drop seizures per month in the 2 months preceding enrollment. A drop seizure is defined as an epileptic seizure (atonic, tonic, tonic-clonic, or myoclonic) involving the entire body, trunk, or head that leads or could lead to a fall, injury, or slumping in a chair.
• * Participant's seizures are non-localized.
• * Participant's scalp recorded EEG has features of LGS, such as multifocal spike, slow spike and wave discharges, and paroxysmal fast activity.
• * Participant must (a) have a stable antiseizure medication (ASM) regimen for the 2 months preceding enrollment and (b) be willing to remain on the stable regimen, as medically able, through the Blinded Evaluation Period; rescue medication for acute seizure clusters are permitted. A stable ASM regimen is defined as no introduction or discontinuation of an ASM, and no change in an ASM dose of more than 25%.
• * Participant is not on a therapeutic diet for epilepsy, or if participant is on a therapeutic diet for epilepsy must (a) have a stable diet for the 2 months preceding enrollment and (b) be willing to remain on the stable diet, as medically able, through the Blinded Evaluation Period.
• * Participant does not have a vagus nerve stimulator (VNS), or if participant does have a VNS must (a) have had the VNS off for the 2 months preceding enrollment and (b) be willing to remain with the VNS off through the Blinded Evaluation Period.
• * Participant is a 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 is willing to give informed consent (or assent, if a minor); if the participant assents or is not able to give informed consent, parent/legal guardian is willing to give informed consent.
• * Participant is able to maintain a seizure log alone or with the assistance of a competent individual.
• * Participant is able to attend study appointments in accordance with the study schedule.
• * Participant is participating in a therapeutic investigational drug or device study (including other RNS System studies).
• * Participant is currently implanted with an electronic medical device that delivers electrical energy to the brain.
• * Participant is currently implanted with an RNS Neurostimulator or NeuroPace Leads.
• * Participant requires procedures that are contraindicated based on current RNS System labeling.
• * Participant is pregnant.
• * Participant has a diagnosed unstable psychiatric disorder or any attempt or expressed intent of suicide over the preceding 6 months.
• * In the opinion of the investigator, the participant has a clinically significant or unstable medical condition \[including alcohol, opioid, recreational cannabis (not for therapeutic purposes) or other drug use disorder\] or a progressive central nervous system disease.
• * Participant is taking any anticoagulants.
• * In the opinion of the investigator, participant is an unsuitable candidate for this procedure.
• * 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 has had therapeutic surgery to treat epilepsy in the preceding 3 months. Participants who have had epilepsy surgery more than 3 months prior to enrollment are eligible.