24/7 EEG SubQ for epilepsy

Level of innovation

Two experts identified the system as novel and of uncertain safety and efficacy. Another agreed that it was a major change to the standard method but that it was one of a few implantable devices currently available. Another expert felt it was an interesting development of an existing procedure.

All experts agreed that this device would not replace standard care but could be used for a small subgroup population alongside standard care. One expert identified a number of opportunities the device could offer. These included monitoring in the community, long-term monitoring allowing observation of patterns in seizures to be identified, including considering treatment response.

Potential patient impact

Two experts reported the main benefit to be more accurate monitoring of seizure frequency and burden than is currently possible with a diary-based system. One expert highlighted that this feedback is critical for management decisions, treatment choices and the effect of lifestyle changes.

Experts reported that the device may have potential in a small group of patients in a diagnostic grey area. This includes those who have frequent seizures when it may help monitor the efficacy of treatment more quickly or help the diagnosis in those who are unable to accurately document the number of seizures they are having. One expert said they felt that individuals with drug-resistant epilepsy and people participating in drug trials may also benefit from this device. One expert felt that it could help find optimum medication regimens more swiftly, potentially leading to fewer outpatient clinic appointments and unscheduled visits. Two experts highlighted that the limited spatial coverage means there is a risk of missing true focal seizures, highlighting the importance of using previous knowledge about the seizure focus to inform the best area to place the implant.

Potential system impact

Experts felt that the system is unlikely to change the current pathway in its present form. One expert highlighted that although the high sensitivity may mean more accurate reporting, people will still need a review because it does not replace the need for in-person reviews of pharmacological changes.

All experts described the adoption of this system to be more expensive than standard care because of the high cost of the device alongside the ongoing cost of standard care. One expert highlighted that this may be offset by reduced outpatient, diagnostic and unscheduled care costs that need to be considered.

All experts raised the need for training, including for implantation and the acquisition and review of acquired data. Two experts said the facilities and time to accommodate the surgical procedure would be more than standard surface electrode placement setting needs, alongside increased time and resources.

Experts highlighted the changes to infrastructure that would be needed to allow clinicians to access the output of the device with relevant IT infrastructure. One expert queried the storage process and whether the data would benefit from being centralised to provide sufficient expertise, if required this would mean patients using these systems may need to attend tertiary centres.

General comments

Experts highlighted some considerations around side effects with the implant, with 2 experts highlighting the pain reported in 2 of the summarised studies. Both studies provided further details that the soreness reported had passed within the study period. Two experts queried the risk of infection with subcutaneous implants, which is a listed possible side effect in the instructions for use (no instances of this are reported in the evidence base).

While the system offers long-term monitoring, 3 experts highlighted the limited spatial sampling the system has as a result. One expert advised that clinicians would need to be satisfied there was a significant chance of relevant seizures being captured before implantation. Two experts highlighted the reported artefacts in the studies that may cause false positives to be recorded. One expert added that using an invasive monitor (albeit minimally invasive), is contentious when the clinical impact of the events being detected is uncertain, highlighting again the importance of patient selection.