S163. Evaluating consciousness and higher cortical cognitive function during elimination of visual fixation in IGE patients with fixation–off sensitivity

Abstract

Introduction This paper set out to demonstrate the clinical features of IGE patients coexisting with FOS, meanwhile to evaluate the consciousness and higher cognitive functions during the long term generalized epileptic discharges elicited by elimination of central vision and fixation. Methods The database of EEG records was searched for FOS and IGE over 4 years from January 2014 to November 2017 at Xijing hospital, Xi’an, China. FOS was evaluated according to the technique proposed by Panayiotopoulos. Photic stimulation procedure was performed according the methodology of updated European algorithm for visual stimulation. In order to evaluate the degree of possible transient impaired consciousness and cognitive function caused by the epileptic discharges, neuropsychological evaluation was performed during video-EEG monitoring with eyes open and with eye closed according the procedure developed by the European taskforce. For comparison, performance during eye open period was set as the normal baseline. Results We identified five (four males and one female) young IGE patients with FOS (one GTCS-only; one JME, two EMA/JS, one IGPE photosensitivity epilepsy). Three of them had family history of epilepsy. All the patients presented with FOS, two of them manifest with FOS associated with seizures captured by video-EEG, four of them coexisted with photosensitivity (two confirmed, two probable). The GTCS was well managed on AED. Two patients complained the GTCS were only provoked by and emotional stress, one patient complained seizures were only triggered by television, the other two patients reported no precipitating factors. The EEG features of FOS presented as high amplitude generalized epileptic discharge predominantly over frontal and occipital regions. Consciousness (awareness and responsiveness) looked like well-preserved during longstanding generalized epileptic discharge induced by elimination of visual fixation, while mild transitory impairment of higher cognitive functions was observed when neuropsychological testing was performed. Conclusion (1) The fixation-off phenomenon as a reflex EEG phenomenon in IGE may either manifest with seizures or represent an EEG abnormality associated with higher cortical cognitive impairment. (2) Neuropsychological assessment can make a highly contribution to the understanding of the mechanisms of consciousness and higher cortical cognitive function in epilepsy. Both concomitant Video-EEG and high-precision neuropsychological testing are necessary to detect the subtle symptom. (3) FOS may be not self-limiting, could occur in several different idiopathic generalized epilepsy syndromes, and therefore, their occurrence alone is not sufficient to characterize a definite epilepsy syndrome.