P01-F Let there be light: Inhibition of spikes by photic stimulation in mesial temporal lobe epilepsy

Abstract

Background Inhibition of epileptic discharges and seizures by sensory stimuli is an interesting field of study with possible clinical translations. We aimed to investigate modulation of epileptiform discharges in patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis (MTLE-HS) via photic stimulation. Material and methods All EEGs recorded in 2018 have been screened for MTLE-HS patients retrospectively. Those EEGs with epileptiform abnormalities have been re-evaluated by two clinical neurophysiologists independently and all spikes were counted in a blinded manner. Spike indices (SI) (spikes per minute) have been calculated for baseline EEG, hyperventilation and photic stimulation periods after a consensus training, based on two different counts. Clinical findings like age, side of HS, hand dominance, antiepileptic drug regimen, disease duration have been noted from their files. Results There were 76 MTLE-HS patients, 33 of them had at least one available EEG with epileptiform abnormalities; clinical data was available for 30 patients. Mean age of these included 30 patients was 34.5 (SD: 12.5), male to female ratio was 8:7, 33.3% had right (n = 10), 26.7% had left (n = 8) and 40% had bilateral MTLE-HS (n = 12). Mean SI during the baseline was 1.17 (SD: 1.4), hyperventilation 2.1 (SD: 2.8) and photic stimulation 0.8 (SD: 2.5). SI was significantly lower during photic stimulation compared to baseline EEG (p = 0.001). Hyperventilation gave rise to an increase in SI (p Conclusions Our findings suggest that photic stimulation have a remarkable inhibitory effect on epileptiform discharges in MTLE-HS patients.