Abstracts

Rationale: The terms "Electrical status epilepticus in sleep (ESES)" and "Continuous spikes and waves during sleep (CSWS)" are variably used in the literature. The aim of this study was to collect the current views of clinical epileptologists regarding the meaning and use of these terms. Methods: We administered an online survey asking the members of the American Epilepsy Society about their views on terminology and conceptualization of ESES and CSWS. The survey was administered through an online survey website (www.surveymonkey.com) and distributed through the "Professional Connection" website of the American Epilepsy Society. All responses were automatically registered by the online survey website. Results: We received 78 responses (72 complete, 6 had some missing data). The demographic features of the respondents are summarized in Table 1. The terms ESES and CSWS were considered synonymous by 39 (54%) respondents, not synonymous by 28 (39%), 5 (7%) respondents stated that they did not know the answer, and 6 respondents skipped this question. The minimum EEG cut-off value of epileptiform activity during sleep for ESES was considered: at least 85% by 37 (52%) respondents, at least 50% by 27 (38%) and any amount of spike-waves by 1 (1%); 6 (9%) were not sure about the cut-off value, and 6 respondents skipped this question. The cut-off value was considered mandatory by 32 (44%), typical but not required by 32 (44%), 8 (11%) did not know the answer and 6 respondents skipped this question. The diagnosis of CSWS was performed based on both clinical and EEG assessment together by 47 (65%) respondents, and based on EEG assessment alone by 21 (29%). The segment used to quantify the epileptiform activity was: all phases of sleep during the whole night by 17 (26%), all non-REM phases of sleep during the whole night by 32 (49%), comparison of epileptiform activity during wakefulness and sleep by 10 (15%), and variable segments for every patient by 3 (5%); 8 respondents used other segments, and 13 respondents skipped this question. Regarding the extent of discharges, 11 (15%) respondents only quantified bilateral and synchronous spike-waves, 22 (31%) quantified bilateral spike-waves even if not synchronous, and 30 (42%) quantified unilateral spike-waves as equivalent to bilateral spike-waves; 9 (13%) respondents did not know the answer and 6 skipped the question. The quantification of epileptiform activity was performed as the percentage of one-second bins occupied by spike-waves by 42 (64%) respondents and as the total number of spike-waves per unit of time in 24 (36%); 4 respondents used other methods and 12 skipped this question. The understanding of the nature and prognosis of CSWS is graphically represented in Figure 1. Conclusions: Our data show that the terms ESES and CSWS are used differently by epileptologists. Variability may impact clinical care, communication and clinical research. A common terminology and diagnostic criteria are urgently needed.