Rationale:
The UMPIRE Study: A First-in-Human Multicentre Trial of Bilateral Sub-Scalp Monitoring for Epileptic Seizure Detection previously reported safety and efficacy at 24 weeks post-implantation. This paper extends those findings, presenting long-term follow-up (LTFU) outcomes in participants monitored for up to three years.
Methods:
This prospective, multicentre study continued follow-up of 26 participants implanted with the Minder® implantable continuous EEG monitoring (iCEM™) system. LTFU outcomes focused on safety, including adverse events (AEs) and serious adverse events (SAEs). Minder EEG recordings were assessed both visually and quantitatively by two board-certified neurophysiologists. Reviews aimed to (1) confirm seizure detection and (2) identify EEG features such as sleep spindles, muscle artefact, and interictal activity. Disagreements were resolved by a third reviewer.
Patient-reported outcomes (PROs) were collected every 12 weeks beyond the 24-week endpoint, up to three years, assessing quality of life, depression, anxiety, and seizure severity. Ethics approval was granted by the St Vincent’s Hospital Melbourne HREC (HREC158/19) and the study was registered (ACTRN12619001587190).
Results:
Between November 2019 and July 2023, 26 subjects were implanted; 22 continued into LTFU. Over half completed follow-up beyond one year, and 7 were followed for the full three years. Only three new device-related AEs occurred after the 6-month endpoint. No serious device- or procedure-related SAEs were reported during LTFU.
Sub-scalp Minder recordings continued to detect seizure events in diverse foci, including frontal, mesial temporal, and hypothalamic regions. Beyond six months, seizures were observed in 17 of 19 (90%) analyzable cases. Sleep spindles and muscle artefact were identified in 18 of 19 cases (95%), while interictal activity was seen in 12 of 19 (63%). Continuous EEG signals remained interpretable throughout follow-up.
Although PROs were exploratory, statistically significant improvement in patient-reported seizure severity was observed at LTFU compared to baseline (p=0.04).
Conclusions:
This study supports the long-term safety and durability of the Minder iCEM system for continuous EEG monitoring in people with epilepsy. The device maintained high signal fidelity and seizure detection capabilities over multiple years, with minimal adverse events. These findings further validate the utility of sub-scalp EEG systems in the long-term management of epilepsy.
Funding:
This study was sponsored by Epiminder Pty Ltd. and received funding from the Victorian Medical Research Acceleration Fund.