24h in-home EEG after a first seizure in adults

Purpose.– The EEG is useful as a predictor of risk of seizure recurrence. However, the sensitivity of a routine EEG in epilepsy is limited, ranging between 25-56% [3]. Repeating routine EEGs may increase the sensitivity to 77% after six recordings [1]. A sleep-deprived EEG improves the yield by 24% in patients with presumed epilepsy after a normal routine EEG [2]. In this study, we evaluate the diagnostic value and feasibility of 24 h in-home EEG in first-seizure patients, as this may improve diagnostic certainty while reducing costs and time-to-diagnosis.

Methods.– First-seizure patients, aged 18 years or older, are randomized to either a group having a standard EEG eventually followed by a sleep-deprived EEG, or a group having a standard EEG followed by a 24 h in-home EEG. In-home EEGs are recorded using a dedicated portable amplifier (TMS-international). The diagnostic value, time-to-diagnosis and number of hospital visits will be assessed.

Results.– At present, 24 first-seizure patients have been included, of which 13 were assigned to the in-home group. None of the standard EEGs contained epileptiform discharges. Ten patients were diagnosed with a first seizure without underlying abnormalities. Five were diagnosed with epilepsy. In two of them, the sleep-deprived EEG showed sharp waves. Two patients had a symptomatic first seizure, whereas in six patients, the first event was probably not epileptic. The average time-to-diagnosis was 70 and 78 days for the sleep-deprived and in-home group respectively and included on average 4.4 and 4.9 hospital visits per patient.

Conclusion.– In-home EEG in first-seizure patients seems feasible. However, the percentage of first-seizure patients with epileptiform discharges is low. Follow-up should demonstrate whether this is caused by the low sensitivity of the EEGs or by the low percentage of first-seizure patients eventually diagnosed with epilepsy. We expect to be able to draw further conclusions when more patients are included.