Abstracts

Rationale: Magnetic resonance imaging (MRI) demonstrates abnormalities in the temporo-polar region in 1/3 to 2/3 of patients with hippocampal sclerosis (HS) that had been named HS- Plus. The rationale of the study is to identify specific clinical-electroencephalogram (EEG) patterns at seizure onset in patients with HS- Plus.Methods: Fifty three ictal video-EEG recordings corresponding to 14 patients with HS have been reviewed, focusing on the EEG features found during the first 30 ictal seconds. The EEG activity has been classified into the following groups: (A) according to spatial distribution: type 1: temporal electrodes on one side; type 2: temporal and adjacent frontal electrodes on one side; and type 3: non-lateralizing electrographic activity; and (B) according to morphology; subtype (a): regular 5–9 Hz rhythmic activity (RA); subtype (b): attenuation or/and low-voltage rapid activity, followed by a 5–9 Hz RA; and subtype (c): irregular EEG sharp waves. We analyzed the clinical symptoms sequence and established the relationship with the ictal EEG patterns.Results: The most frequent symptoms were: presence of an aura (epigastric sensation 40%; fear 40%, and deja vu 40%); oro-alimentary automatisms (65%), unilateral hand automatisms (55%), staring (45%). The sequence of clinical symptoms observed was: aura- behavioural arrest- oro-alimentary automatisms-unilateral hand automatisms Considering spatial distribution and morphology, the most frequent ictal EEG patterns were type 1 (59%), type 2 (35%), and subtype (a): 60%; subtype (b): 31%; and subtype (c): 9%. All seizures with aura and including two or more symptoms of the clinical sequence (68%) were associated with a 1a, 1b, 2a or 2b EEG pattern. Conclusions: The identification of a specific clinical-EEG pattern provides a useful tool for the epileptogenic zone localization in non-invasive pre-surgical assessment of patients with hippocampal sclerosis plus.