The study will investigate whether a novel method to accurately count epileptic seizures, using a CE-marked minimally-invasive ultra long-term subcutaneous electroencephalography (EEG) solution (UNEEG™ SubQ , including 24/7 EEG SubQ), (i) is more accurate than a participant-reported seizure diary; (ii) is feasible and acceptable to participants and clinicians; (iii) reduces impacts of epilepsy and improves quality-of-life; and (iv) provides gains to the healthcare system when rolled-out into the National Health Service (NHS). 33 participants with drug-resistant epilepsy will be implanted with the UNEEG™ SubQ device and will collect data for six months. Annotated seizures from the EEG data will be sent weekly to the treating clinicians, who will communicate with the participants on a monthly basis, and will be free to make any management changes.

Key Inclusion Criteria:

• Have given written informed consent
• Diagnosis of treatment-resistant epilepsy of any syndrome in which seizures are detectable in scalp EEG with two electrodes.
• Adults (≥18 years of age)
• Participant routinely keeps a seizure diary, has a smartphone and is willing to use the electronic diary for the study.
• Experiencing ≥10 seizures per year according to their existing seizure diary.
• Willing and able to comply with study procedures

Key Exclusion Criteria:

• Established current diagnosis of psychogenic non-epileptic attacks (dissociative seizures)
• Frequent vigorous involuntary movements (eg. chorea, athetosis) or frequent parasomnias with major motor components (eg. sleep walking, night terrors)