Abstracts

Previous studies have suggested longer partial seizure duration in sleep, possibly due to NREM facilitation of neuronal hypersynchrony, but have lacked precise localization of the epileptogenic focus. We studied seizure duration in well-localized mesial temporal epilepsy, hypothesizing that partial seizures are longer during sleep than wakefulness. We identified consecutive seizure-free patients following anterior temporal lobectomy (ATL) from 1993-2001 with video-EEG captured seizures in both wakefulness and sleep. We analyzed each seizure for seizure onset time by first clinical or ictal EEG change (whichever was earliest) and seizure offset time by end of the ictal EEG discharge. Seizure types were defined as simple or complex partial, or complex partial with secondary generalization. 23 (10 men and 13 women) seizure-free ATL patients had a total of 335 (176 right and 159 left) temporal onset seizures. 106 (32%) arose from sleep. Mean simple partial seizure duration was somewhat longer during sleep (45.80 seconds) than wakefulness (43.71 seconds), but the difference did not approach statistical significance (p=0.80). There was a trend toward shorter mean complex partial seizure duration during sleep (57.06 seconds) than during wakefulness (66.61 seconds, p=0.07). Secondary generalized tonic-clonic seizures were also slightly shorter during sleep (118.6 seconds) than wakefulness (120.2 seconds). We found no significant difference in seizure duration between sleep or wake onset partial seizures of mesial temporal lobe origin. One possible explanation for this difference could be that sleeping patients may not awaken prior to ictal EEG onset, as compared to awake patients who could consciously experience clinical aura symptomatology and thereby mark their events prior to evolution of ictal EEG alterations. Given our methodology, this could have lead to an underestimation of true seizure duration in sleep-onset seizures. We conclude that mesial temporal onset simple and complex partial seizures with or without secondary generalization are not longer during sleep than in awake states. Future studies of sleep and wake seizure durations in other surgically-established localizations should be conducted.