The purpose of the Responsive Neurostimulator (RNS) system feasibility clinical investigation is to demonstrate safety, and to provide evidence of efficacy of the NeuroPace RNS system in reducing the number of seizures in patients having medically refractory epilepsy.

The clinical investigation has two separate protocols conducted by two different physicians: the Assessment Protocol and the Treatment Protocol.

The physician conducting the Assessment Protocol monitors seizure type, seizure frequency, and seizure severity for each subject. He or she also assesses the subject’s epilepsy-related physical and emotional health at predetermined intervals before and after the subject has been implanted with an RNS system.

After the subject is implanted with an RNS system, the physician conducting the Treatment Protocol manages the RNS system by monitoring and adjusting parameters (when necessary) for the responsive neurostimulation therapy. The physician conducting the Treatment Protocol has the important responsibility of not disclosing to the subject the therapy status (ON or OFF) during the Evaluation Period.

Three distinct time periods define the subject’s participation: Pre-implant, Evaluation, and Follow-up.

The Pre-implant Period begins when an eligible subject enrolls in the clinical investigation. Prior to surgery for implantation of the RNS system, subjects will undergo a neuropsychological evaluation.

The Evaluation Period begins once the subject is implanted with the RNS system. The subject is randomized to therapy ON or OFF for the 4 month duration of the Evaluation Period.

During the Evaluation Period, the physician conducting the Assessment Protocol assesses the subject’s epilepsy-related health at predetermined intervals. The physician conducting the Treatment Protocol uses the implanted RNS system to achieve the best seizure control possible in those subjects randomized to therapy ON. The physician conducting the Assessment Protocol and the subject are blinded to the therapy status during the Evaluation Period.

In the course of the Evaluation Period, any changes in the type of antiseizure medication(s), discontinuation of antiseizure medication(s), or additions of new antiseizure medication(s) are discouraged. This also applies to any medication that has reported antiseizure properties even when prescribed for another indication. Adjustment to the antiseizure medication(s) dose to in order to maintain target blood serum levels or to avoid toxicity is acceptable. Acute, intermittent use of benzodiazepines is also acceptable.

The Follow-up Period is scheduled to begin at four months post-implant of the RNS system, however it will not commence until the appropriate data has been submitted to allow the therapy blinding status to be disclosed.

During the Follow-up Period, therapy may be programmed ON or OFF and medications may be adjusted to provide the most effective care for the subject. The physician conducting the Treatment Protocol uses the implanted RNS system to achieve the best seizure control possible.

Inclusion Criteria:

• Subject has simple partial seizures (motor or sensory) or complex partial seizures (with motor manifestations) with or without secondarily generalized seizures.
• Subject has seizures that are distinct, stereotypical events that can be reliably counted, in the opinion of the investigator, by the patient or caregiver.
• Subject has seizures that are severe enough to cause injuries or significantly impair functional ability in domains including employment, psychosocial, education, and mobility.
• Subject failed treatment with a minimum of two antiseizure medications (used in appropriate doses) with adequate monitoring of compliance and the effects of treatment.
• Subject has remained on the same antiseizure medication(s) over the preceding three (3) months (independent of dose and other than acute, intermittent use of benzodiazepines).
• Subject has a minimum of four (4) or more countable seizures every month over the last three (3) months, as reported from the NeuroPace sponsored Prospective Seizure Frequency clinical investigation.
• Subject is > 18 years old and < 65 years old.
• Subject has undergone diagnostic testing that has established the epileptiform activity onset region(s) as part of his/her standard care to determine candidacy for epilepsy surgery.
• Subject is male, or if female is using a reliable method of contraception (hormonal, barrier method, surgical, or abstention), or is at least two years post-menopause.
• Subject or legal guardian is able to provide appropriate consent to participate.
• Subject can be reasonably expected to maintain a seizure diary alone or with the assistance of a competent individual.
• Subject is able to complete regular office visits and telephone appointments per the protocol requirements.
• Subject is willing to be implanted with a responsive neurostimulator (RNS) system as a treatment for his/her seizures.
• Subject is able to tolerate a neurosurgical procedure.
• Subject is considered a good candidate to be implanted with an RNS system.

Note: 1 month = 28 days

Exclusion Criteria:

• Subject has been diagnosed with psychogenic or non-epileptic seizures in the preceding year.
• Subject has been diagnosed with primarily generalized seizures.
• Subject has experienced unprovoked status epilepticus in the preceding year.
• In the opinion of the investigator, the subject has a clinically significant or unstable medical condition or a progressive central nervous system disease.
• Subject has been diagnosed with active psychosis, severe depression, or suicidal ideation in the preceding year.
• Subject is pregnant or planning on becoming pregnant in the next year.
• Subject is on the ketogenic diet.
• Subject was enrolled in a therapeutic investigational drug or device study in the preceding year.
• Subject has an implanted Vagal Nerve Stimulator (VNS).
• Subject has had therapeutic surgery to treat epilepsy in the preceding year.
• Subject is implanted with an electronic medical device that delivers electrical energy to the head or body.
• Subject is on chronic anticoagulants or, in the opinion of the investigator, subject is an unsuitable candidate for cranial surgery for any other reason.
• Subject had a cranial neurosurgical procedure in the previous month.
• Subject requires repeat MRIs.
• Subject's seizure onset zone(s) is/are located below the level of the subthalamic nucleus or, in the opinion of the investigator, the necessary lead placement would present too high a risk.

Note: Subjects who have had epilepsy surgery (resective, corpus callosotomy, or ablation) greater than one year ago are still eligible.