Summary: Purpose: One hundred patients with photosensitive epilepsy were investigated as part of an ongoing follow-up study. Average duration of follow-up was 14 years; mean age at follow-up was 27 years.Methods: All patients were EEG investigated using a standard technique of intermittent photic stimulation (IPS). The presence of a photoparoxysmal response (PPR) or a degraded PPR indicated the presence of photosensitivity.Results: Seventy-seven patients became seizure free. Of the untreated patients, photosensitivity disappeared in 14 patients but was present in 32 patients. Of the patients who were treated, 31 showed evidence of PPRs or degraded PPRs, but 23 patients no longer showed evidence of photosensitivity. Thirty-two mothers had 67 children during the follow-up period. Thirteen have so far proved to be sensitive to IPS in the laboratory and four have also had photosensitive seizures induced in the outside environment. Nine of the children have been found not to be photosensitive nor have they had seizures.Conclusions: This study suggests that photosensitivity persists in at least two thirds of patients with photosensitive epilepsy and that valproate is effective in controlling this photosensitivity. Key Words: Photosensitive epilepsyPhotoparoxysmal response-Intermittent photic stimulation-Sodium valproate.There are remarkably few long-term studies of the course of photosensitivity in patients with photosensitive epilepsy. In 1978 we reported (1) on 167 patients who had been studied over a period of 512 years. We studied changes in photosensitivity range, that is, the range of intermittent photic stimulation (IPS) flash rates to which the patient is sensitive (2) and demonstrated that without drug intervention, there was no significant change in sensitivity range over a period of 7-12 years. In 1983 we selected (from our original 1975 cohort) 82 patients and four siblings, of whom 72 had reached the age of 20 years, the rest being between 15 and 19 years old. The mean duration of follow-up was 9.8 years. Of patients, 75% were treated with sodium valproate, and the drug had been withdrawn in 15 patients but had been restarted in eight because of the return of photosensitivity. Photosensitivity was no longer present in 55 patients, but 45 (82%) of these were receiving medication; photosensitivity persisted in 31 patients despite medication in 23 (74%). It was noted that, without change in medication, photosensitivity disappeared as the patients became older, and therefore it was proposed that photosensitivity disappeared spontaneously at -24 years of age (3). Our report concerns 91 patients and nine close relatives who have attended for repeated EEG investigations over the period from 1968 through 1993. As far as possible, we have selected patients from our 1986 study, but six were excluded on the grounds of unreliability of attendance, and we have added 16 patients who have regularly attended over 10 years and four siblings of the patients in the 1986 study. METHODSA standard technique of IPS (2) was used...

Nine patients who had epileptic attacks while playing computer games were studied in the laboratory. Patients had an EEG recorded as well as their response to intermittent photic stimulation (IPS) at flash rates of 1-60 fps. In addition, pattern sensitivity was assessed in all patients by a gratings pattern. Only 2 patients had no previous history of convulsions, and only 2 had a normal basic EEG. All but 1 were sensitive to IPS, and all but 1 were pattern sensitive. Most patients were male, but although this appears to conflict with previously published literature results regarding the sex ratio in photosensitivity, it was due to the male predominance of video game usage. We compared our results with those reported in the literature. Diagnosing video game epilepsy requires performing an EEG with IPS and pattern stimulation. We propose a standard method of testing.

Summary:Purpose: We aimed to elucidate the mechanisms underlying video-game epilepsy by comparing the flicker-and spatial-frequency ranges over which photic and pattern stimulation elicited photoparoxysmal responses in two different populations: (a) 25 patients with a history of seizures experienced while playing video games; and (b) 25 age-and medication-matched controls with a history of photosensitive epilepsy, but no history of video-game seizures.Methods: Abnormality ranges were determined by measuring photoparoxysmal EEG abnormalities as a function of the flicker frequency of patterned and diffuse intermittent photic stimulation (IPS) and the spatial frequency of patterns on a raster display.Results: There was no significant difference between the groups in respect of the abnormality ranges elicited by patterned or diffuse IPS or by spatial patterns. When the groups were compared at one specific IPS frequency (-50 Hz), however, the flicker frequency of European television displays, the video-game patients were significantly more likely to be sensitive.Conclusions: The results suggest that video-game seizures are a manifestation of photosensitive epilepsy. The increased sensitivity of video-game patients to IPS at 50 Hz indicates that display flicker may underlie video-game seizures. The similarity in photic-and pattern-stimulation ranges over which abnormalities are elicited in video-game patients and controls suggests that all patients with photosensitive epilepsy may be predisposed toward video-game-induced seizures. Photosensitivity screening should therefore include assessment by using both IPS at 50 Hz and patterns displayed on a television or monitor with a 50-Hz frame rate. Key Words: Photic stimulation-Flicker frequency-Pattern stimulation.Reports of seizures associated with playing video games have appeared in the literature since 1981 (1,2) and have suggested that such seizures are elicited by photic or pattern stimulation. Specifically, patients show abnormal sensitivity to intermittent photic stimulation (IPS) and high-contrast patterns (3). Awareness of the risk of video-game seizures has increased in manufacturers of video games, many of whom include warnings of the risk of seizures on their games. Accordingly, the perception of risk has increased in video-game users who have epilepsy, and this is not confined to individuals with photosensitive epilepsy (4). Perception of risk is confounded by the often prolonged period individuals spend playing games; seizures in individuals with no electrophysiologic evidence of photosensitive epilepsy may be fortuitous. Alternatively, these individuals' predisposition toward video-game epilepsy may not have been identified because of inadequate testing procedures. It is essential, therefore, to devise an effective test for predisposition toward video-game epilepsy. A prerequisite for such a test is an understanding of the mechanisms underlying video-game seizures. This study aimed to elucidate the mechanisms of video-game epilepsy by comparing the abnormal...

Summary: Purpose: The continued presence of EEG abnormalities in patients with a history of photosensitive seizures is used to signify the persistence of photosensitive epilepsy. The extent to which this approach places patients at risk of seizures is unclear, however. We describe those EEG abnormalities that may be tolerated with low risk of further seizures, and those that are indicative of poor seizure control.Methods: Fifty patients with EEG evidence of persistent photosensitive epilepsy underwent photosensitivity testing with diffuse and patterned light; 58% of patients continued to experience seizures, and 42% were seizure free. The incidence of EEG abnormalities to diffuse and patterned intermittent photic stimulation (IPS) was analysed as a function of recent seizures.Results: All patients showed EEG abnormalities to patterned IPS; there was n o significant association between patterned IPS and poor seizure control. EEG abnormalities to diffuse IPS occurred in 58% of patients, and 76% of these patients had experienced a seizure within the previous year. These patients were more than twice as likely to be poorly controlled than those who showed abnormalities only to patterned IPS. These results were consistent for both medicated and unrnedicated patients.Conclusions: EEG abnormalities to patterned IPS can be used to signify the persistence of photosensitive epilepsy, but abnormalities to diffuse IPS are more likely to indicate the patient is poorly controlled and at risk of further seizures.

Over the last decade, vigorous efforts have been made by neuroscientists to unravel the cellular and molecular basis of photosensitive Epileptogenic activities in the central nervous system (CNS). Many neurotransmitters are implicated in brain activities but the extent to which they participate in these activities needs to be clarified. This review discusses the involvement of serotonin (5-hydroxytryptamine, 5-HT) in photosensitive epilepsy. The biosynthesis, metabolism, and structural and functional distribution of serotonin in the brain, and the role of 5-HT, its precursors, metabolites, receptors, agonists, antagonists, and the enzymes of reaction in photosensitive epileptogenic activity with reference to 5-HT cortical density, are discussed. The effects of biosynthetic and metabolic impairments in the serotonergic system, and the extent to which they contribute to the elicitation of myoclonic phenomena, hallucination, impulsivity, and migraine (HIMM) in photosensitive epilepsy are critically reviewed, and supported by evidence from animal models of photosensitive epilepsy. This evidence is correlated with the clinical findings in human photosensitive epilepsy.