Study on photo-pattern sensitivity in patients with electronic screen game-induced seizures (ESGS): Effects of spatial resolution, brightness, and pattern movement

Purpose: With the ever-increasing popularity of computers, electronic scree n game-induced seizure (ESGS) is beginning to pose a serious social problem . To elucidate the pathophysiology of ESGS, with the ultimate goal of preve ntion, we have been studying photo-pattern sensitivity in detail with a pat tern-stimulation test using a CRT (cathode ray tube) display. This method i s referred to as the "CRT-pattern test." Methods: We studied 17 patients brought to our department for evaluation of ESGS. EEG responses were recorded during exposure to various patterns cons isting of three elements: spatial resolution, brightness perception, and pa ttern-movement recognition displayed on a CRT monitor. Photo-paroxysmal res ponse (PPR) frequencies were compiled for each stimulation. Results: PPR was induced by the CRT-pattern test in nine of the 17 cases. I n four cases, PPR induction was obtained only after introducing CRT-pattern tests in addition to standard intermittent photic stimulation (IPS). The r ate of PPR induction differed according to the type of pattern, spatial fre quency, and pattern-reversal frequency. However, neither the clarity of the edges of a pattern nor changes in the brightness of a pattern element had any effect on the rate of PPR induction. With the exception of a few subjec ts, the stimulation caused by pattern movement was not effective in eliciti ng PPR. Six cases in whom spatial resolution was involved showed occipital dominance in PPR provocation, and three in whom brightness perception and p attern movement recognition was involved showed frontal dominance. Conclusions: The CRT-pattern test is useful for identifying patients with p hotosensitivity among patients considered to have incidental or nonphotosen sitive seizures unresponsive to standard IPS. Patients with ESGS caused by photosensitivity can be divided into two groups: those with occipital domin ance for PPR provocation, in whom spatial resolution is involved; and anoth er group with frontal dominance, in whom brightness perception and pattern- movement recognition (or possibly perception of colors) are involved.