Photosensitive benign myoclonic epilepsy in infancy

To describe the electroclinical features of subjects who presented with a photosensitive benign myoclonic epilepsy in infancy (PBMEI).

The patients were selected from a group of epileptic subjects with seizure onset in infancy or early childhood. Inclusion criteria were the presence of photic-induced myoclonic seizures and a favorable outcome. Cases with less than 24 month follow up were excluded from the analysis.

Eight patients were identified (4 males, 4 females). Personal history was uneventful. All of them had familial antecedents of epilepsy. Psychomotor development was normal in 6 cases, both before and after seizure onset. One patient showed a mild mental retardation and a further patient showed some behavioral disturbances. Neuroradiological investigations, when performed (5 cases), gave normal results. The clinical manifestations were typical and could vary from upward movements of the eyes to myoclonic jerks of the head and shoulders, isolated or briefly repetitive, never causing a fall. Age of onset was between 11 months and 3 years and 2 months. Characteristically, the seizures were always triggered by photic stimulation. Non photo-induced spontaneous myoclonic attacks were reported in 2 cases during the follow-up. Other types of seizures were present at follow-up in 2 cases. The outcome was favorable, even if, usually, seizure control required high AED plasma levels. Since the clinical symptoms were not recognized early, some patients were treated only many years after the onset of symptoms.

Among BMEI patients, our cases constitute a subgroup in which myoclonic jerks were always triggered by photostimulation, in particular at onset of their epilepsy.