Purpose: An increased propensity for seizures is associated with different stages of the sleep-wake cycle. In this study, we prospectively analyzed patients with new-onset epilepsy and investigated the clinical correlates of the yield obtained from sleep electroencephalography (EEG) recordings in patients with a normal wakefulness EEG.
Methods: All patients admitted to our epilepsy unit due to unprovoked epileptic seizures and not yet treated with antiepileptic drugs were recruited consecutively for the last three years. All had a routine EEG at wakefulness (WEEG), and those with no epileptiform activity had a video-EEG recording during sleep (SEEG).
Results: We investigated a total of 241 patients; 129 patients (53.5%) had both wakefulness and sleep EEG recordings. The patients with abnormal WEEG were older than those with normal WEEG (p = 0.005). Abnormal WEEG was detected in only 31.2% of patients with focal seizures, but in 77.3% of patients with generalized seizures (p < 0.001). WEEG was abnormal in 44.0% of patients with diurnal seizures, but in 27.5% of nocturnal seizures (p = 0.007). Abnormal WEEG was present in 75.5% of patients with a presumed genetic origin and in 59.3% of patients with structural etiology (p < 0.001). Sleep EEG detected an abnormality in 41.8% of patients with normal WEEG; of these, 82.8% were focal abnormalities. In contrast, the majority of abnormalities detected in WEEG were generalized (55.8%, p < 0.001).
Conclusion: Our results showed a greater likelihood of abnormal WEEG in older patients and in those with generalized epilepsy, diurnally precipitating seizures, and epilepsy of presumed genetic origin.
Keywords: Electroencephalography; Seizures; Sleep; Wakefulness.
Copyright © 2015 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.