Low-luminance visual stimuli compared with stroboscopic IPS in eliciting PPR in photosensitive patients

Purpose: Photosensitivity is thought to play the most important role in the genesis of electronic screen games induced seizures (ESGIS). To elicit photoparoxysmal response (PPR) effectively, we performed EEG activation by low-luminance visual stimuli: 20 cd/m² deep-red flicker and flickering 2 c/deg geometric pattern stimuli produced by strobo-filters. We investigated efficacy of eliciting PPR by use of Grass PS33-plus stroboscopic 18-Hz intermittent photic stimulation (IPS) and low-luminance 18-Hz visual stimuli. Methods: We studied 31 photosensitive patients. We gave stroboscopic IPS (eyes closed and eyes open); after deep-red flicker stimulation (eyes open), we gave flickering geometric-pattern stimuli by using dot, vertical grating, and horizontal grating patterns. Results: Stroboscopic IPS elicited PPR in 14 patients, whereas absence of PPR provocation was found in 17 patients. Low- luminance visual stimuli elicited PPR in 30 patients, whereas absence of PPR provocation was found in only one patient. These PPR provocation differences in both stimuli were statistically significant (p < 0.001). Conclusions: The data suggest that low-luminance visual stimuli as described are useful for EEG diagnosis of ESGIS when seizures are thought to be due to photosensitivity.