Mark Richardson is Professor of Epilepsy and the Head of the School of Neuroscience at King’s College London as well as a Consultant Neurologist at King’s College Hospital. His research focus is on understanding the underlying mechanisms of seizure onset in terms of mathematical models as well as examining how antiepileptic drugs alter brain networks. In addition, he investigates the long timescale mechanisms of epilepsy, through long-term monitoring, using wearable and implantable sensors.

Ultra long-term ambulatory subcutaneous EEG: a novel technology

Prof Mark Richardson FRCP PhD, Professor of Epilepsy, King’s College London

Ultra longterm subcutaneous EEG monitoring is a rapidly emerging new technology. One system already has CE approval and is available on the market in the UK, and is currently being investigated in several trials. Several other systems are in development or already in early-phase trials. Clinicians in EEG services may be unfamiliar with this technology, which, depending on trial outcomes, may be adopted into UK NHS practice in the next few years.

Implantation of the electrodes is a minimally-invasive and well-tolerated local anaesthesia procedure. In the recently-completed SUBER trial funded by the Epilepsy Foundation of America, which recruited exclusively in the UK, the device was well-tolerated by patients, the data quality was high and remained high throughout months of recording, and typical EEG features were readily identified. Disadvantages include the requirement to wear a small external data-logging device, and very limited spatial coverage with very few electrode contacts.

Potential use cases include objective and automated seizure counting for management of epilepsy, and longterm sleep monitoring. There are substantial challenges in adopting this new technology. Enormous quantities of EEG data are generated, which create logistical challenges to transmit, store, analyse and report the data; it is likely AI-supported systems will need to be developed. The impact on clinical workflows and patient outcomes remains to be established. A pivotal diagnostic accuracy study is underway in the USA, and a ‘real-world’ trial funded by NIHR has just commenced in the UK.

Ultra longterm subcutaneous EEG monitoring has the potential to emerge as an important new tool in clinical neurophysiology