Abstracts

Rationale: Electrical status epilepticus in sleep is characterized by the marked potentiation of epileptiform activity during non-REM sleep, leading to a near-continuous bilateral or lateralized pattern of slow spikes and waves, occupying a significant proportion of non-rapid eye movement (non-REM) sleep. Sleep potentiation of epileptiform activity (SPEA) is generalized and bilateral symmetric in some patients while others have a more lateralized or focal area of SPEA. We studied differences in the clinical presentation of patients with generalized SPEA compared to patients with focal or lateralized SPEA.Methods: Patients up to age 20 years were selected from our video-electroencephalogram (EEG) monitoring unit with at least one overnight EEG recording in the period 2001-2009 and with SPEA, that is, an epileptiform activity at least a 50% higher during non-REM sleep than during wakefulness by EEG report. The EEG epileptiform activity was quantified by calculating the spike-wave percentage (SWP) as the percentage of one-second bins containing at least one spike-wave complex during the first five minutes of every hour of slow wave sleep. Focal predominance of epileptiform activity was visually assessed. The potentiation of the epileptiform activity from wakefulness to non-REM sleep was considered generalized when the epileptiform discharges were present in all four lobes of each hemisphere; focal and multifocal potentiation of epileptiform activity was classified as focal.Results: 85 patients were included with a median age of 7.3 years (range: 2.6-19.3 years), males: 54 (63.5%). 52 (61.2%) patients had a SWP of at least 50%, 19 (22.4%) patients had a SWP of at least 85%. Clinical features can be found in table 1 and seizure types in table 2. 67 (78.8%) patients had focal SPEA while 18 (21.2%) had generalized SPEA. When comparing patients with focal to generalized SPEA we did not detect a difference in gender (62.7%vs66.7% males, p=0.755), age (7.9vs8 years, p=0.946), mean SWP (55.1vs53%, p=0.786), presence of structural brain abnormality (49.2%vs31.3%, p=0.202), seizure disorder (77.6%vs88.9%, p=0.507), language disorder (47.8%vs38.9%, p=0.502), autistic spectrum disorder (17.9%vs33.3%, p=0.195), attention deficit hyperactivity disorder (9%vs5.6%, p=1), learning/memory problems (13.4%vs11.1%, p=1), global developmental delay (26.9%vs33.3%, p=0.588), acquired epileptic aphasia (11.9%vs16.7%, p=0.693), motor problems (23.9%vs5.6%, p=0.106), or behavioral problems (9%vs11.1%, p=0.675). We compared means using t-test and compared frequencies using either Pearson s chi-square or Fisher s exact test.Conclusions: Our data suggest that the demographic and clinical features do not significantly differ between patients with focal SPEA when compared to patients with generalized SPEA. This supports the notion that generalized SPEA is not an isolated clinical syndrome, and that both focal and generalized SPEA are seen in a broad clinical spectrum of patients with spike activation.