Seizure Timing and Limitations of Video-EEG Monitoring in Focal Epilepsy with Seizures Exclusively Occurring during Sleep
Meryem Senem Yıldız, Tuba Güney, Zehra Uzun, Serap Saygı, F. İrsel Tezer
A
BSTRACT
Objective:
Video-EEG monitoring (VEM) can be classified into short-term and long-term monitoring. Short-term VEM (S-VEM) may fail to capture ictal activity, thereby restricting the ictal EEG findings necessary for the localization of the seizure onset zone in focal epilepsy syndromes. We retrospectively analyzed focal epilepsy patients whose seizures occurred only during sleep on VEM.
Materials and Methods:
Patients monitored between 2005 and 2023 at our VEM unit with seizures exclusively during sleep were reviewed. Patients were classified into temporal and extratemporal lobe epilepsy (ETLE) groups, and seizure timing was analyzed in relation to working (08:00–17:00) and non-working hours (17:00–08:00). Age, duration of hospital stay, admission-to-seizure interval, seizure frequency, and magnetic resonance imaging findings were compared.
Results:
Among 1961 VEM patients, 178 fulfilled the inclusion criteria, including 106 with TLE and 61 with ETLE. The most common pathology was hippocampal sclerosis (50%). Sleep-related hypermotor epilepsy (SRHE) was observed in 47 patients: 42 ETLE, 4 TLE, and 1 unlocalized. Most seizures occurred outside working hours, with TLE patients more likely to have non-working hour seizures, while ETLE patients showed higher seizure frequency and clustering. Besides that, fewer recorded seizures, TLE patients had longer hospital stays and admission-to-seizure intervals.
Conclusion:
In focal epilepsy patients with seizures exclusively during sleep, TLE was the most common type, and hippocampal sclerosis was the most frequent pathology, while SRHE was more prevalent in ETLE. S-VEM had a limited diagnostic yield in both groups, highlighting the need for alternative or prolonged monitoring adapted to seizure timing and epilepsy subtype.