Long-Term Adherence to a Subcutaneous Two-Channel EEG System in Patients With Focal Epilepsy

Outpatient seizure monitoring is crucial for optimizing treatment strategies in epilepsy; however, traditional approaches such as seizure diaries and wearables have limitations in accuracy and practicality. This study evaluated the adherence and utility of an implanted subcutaneous EEG monitoring system in patients with focal temporal lobe epilepsy.

At a tertiary epilepsy center, patients with focal epilepsy received a subcutaneous two-channel EEG system for ultra-long-term monitoring. The system includes a subcutaneously implanted electrode for data recording and a behind-the-ear companion device for the power supply and data transmission. Patient adherence to the device was evaluated using generalized estimating equations, considering sex, daytime/nighttime periods, age, and temporal course of measurements. The correlations between adherence and electrographic or diary-recorded seizures were also assessed.

Fifteen adult patients (mean age: 45.6 years, 6 females) were monitored for an average of 200.6 days, with 416 electrographic seizures confirmed in 13 patients. The median adherence was 89.3% (interquartile range, [75.6%, 93.4%]), with females showing significantly higher adherence than males ( β , -1.1600; P = 0.049). Seizure diary reporting sensitivity and precision were 20.8% and 56.4%, respectively, compared with confirmed electrographic seizures. Adherence correlated positively with confirmed electrographic seizures ( r , 0.40; P, 0.004), but not with diary reports ( r , -0.22; P, 0.13).

Patients using the subcutaneous EEG system demonstrated high adherence and reliable seizure monitoring, suggesting that it could serve as a valuable tool for managing focal epilepsy in clinical practice.