Abstracts

Rationale: Our goal was to evaluate by behavioral testing during and after seizures whether deficits in memory, language, and consciousness are correlated with underreporting of seizures, and relate these deficits to seizure type and anatomical site of seizure onset. Prior work suggests that seizures originating in the dominant hemisphere are more likely to go unrecognized, and that impairment in consciousness play a role in seizure awareness. Little work has been done to directly measure attention, language, and memory performance during seizures of different types, to determine which seizures present the highest risk of not being recognized. Knowledge of which seizure types and localizations cause the greatest risk for seizure unawareness will provide useful information for clinicians treating patients, and can also help reveal the mechanisms of impaired function. Methods: Twenty nine patients who underwent presurgical evaluation in a Video/EEG (VEEG) monitoring unit were recruited. Responsiveness during seizures was assessed retrospectively by reviewing the patient behavior on the video data captured during the monitoring session. For comparison with objective data obtained through VEEG monitoring, we used 3 testing instruments to evaluate patient subjective report of seizures: 1. Admission questionnaire; 2. Patient seizure log; 3. Daily seizure questionnaire. The admission questionnaire was given once to all patients to assess their self perception of seizure awareness. Patients then received a seizure log where they were asked to note any seizure or unusual sensation they may have experienced during the monitoring session. The daily seizure questionnaire was administered once daily and contained questions carefully chosen to determine patient s awareness of seizures that occurred in the past 24 hours. We took into consideration possible clues (such as being told by family members or staff) that may have helped patients realize that they had a seizure. Results: Patients who had no seizures, did not finish the questionnaires, or had non-epileptic seizures were excluded from the analysis. Data from a total 16 patients were included in the study. Overall, 64 seizures were recorded (24 simple partial seizures, 22 complex partial seizures, 4 secondary generalized seizures and 14 unclassified). Patients were unaware of 47% of all recorded seizures. Seventy three percent of all complex partial seizures were not reported. In contrast, only 8% of all simple partial seizures were not reported (?2 = 19.983, p < 0.001). Five of six patients who reported on their admission questionnaire to be perfectly aware of their seizures actually were perfect documenters. Conclusions: This study demonstrates that almost half of all recorded seizures during inpatient VEEG monitoring are unrecognized by the patients. Impaired consciousness during seizures appears to be one of the main factors that influence patient ability to recognize and accurately report their seizures. Further study is needed to investigate to what extent altered memory function or language impairment may participate in reducing patient seizure report.