Abstracts

Rationale: Photosensitivity is a common trait among children with primary paediatric epilepsies. Testing of photoparoxysmal (PPR) responses is challenging in children and EEG assisted by an optometrist is usually not readily available. Colored filters are not commonly used during EEG. The objective of this study was to assess whether the use of sequentially photic-stimulator installed color filters affected the photoparoxysmal response of children with primary epilepsy Methods: Thirty-three children and adolescents with primary epilepsy (mean age=12.6 ) with abnormal photo-paroxysmal responses were identified among 5510 sequential EEG studies completed between August 2010 and Feb 2012 at Alberta Children's Hospital in Calgary. The sample consisted of 9 males (27.2%) and 24 females (72.7%). Thirteen (39.3%) children were already on antiepileptic medication at the time of the evaluation. 10-20 EEG montages and conventional intermittent unfiltered photic stimulation (IPS) recommended parameters were used initially. After identifying the initially unfiltered inducing photo-paroxysmal responses (PPR) on the conventional testing, to identify the potentially inhibiting effect of the filters, the photic stimulation testing was repeated applying sequentially a red, a yellow, a orange, a green and a blue filters on the photic stimulator box. All EEGs were performed by experienced and registered certified EEG Technologists. Results: The use of the green and blue filters blocked the photoparoxymal response in 30 (90.9%) and 29 (87.9%) children respectively. The red filter blocked the PPR in 13 (33.9%) children and yellow and orange filters only blocked it in 3 (9.1 %) and 6 (18.1%) respectively. No photoconvulsive events were induced during the repetitive filter testing. Conclusions: The use of strobic-photic stimulator mounted colored filters during EEG testing may be useful to detect specific inhibition of photoparoxysmal inducing frequencies in children with epilepsy. Blue and green color filters appear to be more effective blocking these epileptogenic photoparoxysmal responses. Low-cost colored filters can be safely and easily implemented for the assessment of photosensitivity during routine pediatric EEG.