Abstracts

Photosensitive patients may constitute an underreported number of cases. This fact can be due to the ineffectiveness of appropriate testing during EEG. We report 4 patients with a very peculiar photosensitivity pattern recorded only with partial environmental illumination. We report 4 patients who were referred consecutively in a period of 1 month for routine EEG in a secondary care university center and presented generalized discharges precipitated by eye closure in partial environmental illumination. Four healthy female patients aged 12-16yr., who presented new-onset epileptic fits, characterized by generalized tonic-clonic seizures in three and typical absence seizures in one, were referred for EEG examination. All of them had generalized discharges consisting of irregular spike-wave activity predominating in occipital areas after eye-closure in partial illuminated environment. Only one, who was taking phenobarbital, had photoparoxystic response and the other three were not receiving antiepileptic drugs, including one that was in the puerperal period. No discharges were elicited after eye closure in total darkness. Although photosensitivity is rare, the increase of sensibility of the EEG with single tasks such different intensity light stimulation, may grow the number of reported cases, improve diagnostic approach and select patients for genetic studies. Seasonal factors may play a role in precipitation seizures in some photosensitive patients.